CN110224779B - Method, device, equipment and medium for calculating absolute time of equipment for receiving and sending message - Google Patents
Method, device, equipment and medium for calculating absolute time of equipment for receiving and sending message Download PDFInfo
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- CN110224779B CN110224779B CN201910544117.9A CN201910544117A CN110224779B CN 110224779 B CN110224779 B CN 110224779B CN 201910544117 A CN201910544117 A CN 201910544117A CN 110224779 B CN110224779 B CN 110224779B
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- H—ELECTRICITY
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Abstract
The embodiment of the invention discloses a method, a device, equipment and a medium for calculating the absolute time of a device for receiving and sending a message. The method comprises the following steps: acquiring receiving and sending relative time, reference calculation relative time and reference calculation absolute time which respectively correspond to a message receiving stage and a message forwarding stage of an event message; in the message receiving stage, the receiving and transmitting relative time is the relative time of the exchange chip for receiving the event message, the event message is reported after being received by the exchange chip, and in the message forwarding stage, the receiving and transmitting relative time is the relative time of the event message leaving the exchange chip, and the event message is actively reported to the CPU after receiving the CPU inquiry instruction by the exchange chip; and calculating the transceiving absolute time matched with the transceiving relative time according to the transceiving relative time, the reference calculation relative time and the reference calculation absolute time. By the technical scheme, the CPU can effectively reduce the overhead of frequently accessing the timestamp register of the switching chip under the condition that the PTP message is in a large burst.
Description
Technical Field
The embodiment of the invention relates to the technical field of communication, in particular to a method, a device, equipment and a medium for calculating the absolute time of a device for receiving and sending a message.
Background
A Precision Time Protocol (PTP) is defined in IEEE 1588, and the PTP defines an event (event) message and a general (general) message. Event messages are messages that contain accurate timestamps for transmission and reception, whereas ordinary messages do not require accurate timestamps. The event message comprises a synchronization message (Sync), a Delay request message (Delay _ Req), a peer Delay request message (Pdelay _ Req), and a peer Delay response message (Pdelay Resp). Taking the synchronous message as an example, the hardware of the slave clock in the PTP domain obtains the most accurate matching time when the synchronous message is transmitted and received, and then the slave clock achieves synchronization with the master clock by exchanging the synchronous message with the master clock.
In the prior art, timestamps of PTP implementing message transmission and reception are generally stamped in a relevant timestamp register of a switch chip, and are read by accessing the relevant register when the timestamp is needed subsequently. In practical application, when a CPU receives a large amount of data messages, a large amount of PTP messages are in a burst state, and at this time, the CPU has a high operating pressure, and meanwhile, a relevant timestamp register of a switch chip needs to be frequently accessed, which further increases the operating overhead of the CPU.
Disclosure of Invention
The embodiment of the invention provides a method, a device, equipment and a medium for calculating the absolute time of a device for receiving and sending a message, so as to reduce the time overhead of a CPU (central processing unit) of PTP (precision time protocol) clock equipment for accessing a hardware register.
In a first aspect, an embodiment of the present invention provides a method for calculating an absolute time for a device to receive and send a packet, where the method includes:
acquiring the receiving and sending relative time, the reference calculation relative time and the reference calculation absolute time which respectively correspond to the message receiving stage and the message forwarding stage of the event message;
in the message receiving stage, the receiving and sending relative time is the relative time for the exchange chip to receive the event message, and the event message is actively reported to the CPU through the exchange chip after being received, and in the message forwarding stage, the receiving and sending relative time is the relative time for the event message to leave the exchange chip, and the event message is actively reported to the CPU through the exchange chip after receiving the CPU inquiry instruction;
and calculating the transceiving absolute time matched with the transceiving relative time according to the transceiving relative time, the reference calculation relative time and the reference calculation absolute time.
In a second aspect, an embodiment of the present invention further provides a device for calculating absolute time for a device to receive and send a packet, where the device includes:
the computing data acquisition module is used for acquiring the receiving and sending relative time, the reference computing relative time and the reference computing absolute time which respectively correspond to the message receiving stage and the message forwarding stage of the event message;
in the message receiving stage, the receiving and sending relative time is the relative time for the exchange chip to receive the event message, and the event message is actively reported to the CPU through the exchange chip after being received, and in the message forwarding stage, the receiving and sending relative time is the relative time for the event message to leave the exchange chip, and the event message is actively reported to the CPU through the exchange chip after receiving the CPU inquiry instruction;
and the calculating module is used for calculating the transceiving absolute time matched with the transceiving relative time according to the transceiving relative time, the reference calculation relative time and the reference calculation absolute time.
In a third aspect, an embodiment of the present invention further provides a clock device, including a memory, a processor, and a computer program that is stored in the memory and is executable on the processor, where the processor implements the method for calculating the absolute time for transmitting and receiving a message by the device according to any embodiment of the present invention when executing the computer program.
In a fourth aspect, an embodiment of the present invention further provides a computer-readable storage medium, where a computer program is stored, and when the computer program is executed by a processor, the computer program implements the method for calculating the absolute time for sending and receiving a packet by a device according to any embodiment of the present invention.
In the embodiment of the invention, when a PTP (precision time protocol) runs, in a message receiving stage, the relative time of the exchange chip for receiving the event message is firstly obtained, then one reference calculation relative time and the reference calculation absolute time corresponding to the reference calculation relative time are selected, and the absolute time of the exchange chip for receiving the event message is calculated according to the relative time of the exchange chip for receiving the event message, the reference calculation relative time and the reference calculation absolute time; at a message forwarding node, firstly, the relative time of the event message leaving the exchange chip is obtained, then, a reference calculation relative time and a reference calculation absolute time corresponding to the reference calculation relative time are selected, and further, the absolute time of the event message leaving the exchange chip is calculated according to the relative time reference calculation relative time and the reference calculation absolute time of the event message leaving the exchange chip. In the technical scheme, the relative time of the exchange chip for receiving the event message is reported to the CPU by the exchange chip after the exchange chip receives the event message, the relative time of the event message leaving the exchange chip is reported to the CPU by the exchange chip after the exchange chip receives the CPU inquiry instruction, and the relative time is not acquired by the CPU in a mode of actively accessing the time stamp register of the exchange chip, so that the cost of accessing the time stamp register of the exchange chip is reduced when the CPU receives and transmits the message absolute time in the computing equipment, and particularly, the cost of frequently accessing the time stamp register of the exchange chip by the CPU can be effectively reduced under the condition that a large number of PTP messages are in a burst.
Drawings
Fig. 1 is a flowchart of a method for calculating absolute time for a device to receive and transmit a message according to a first embodiment of the present invention;
fig. 2 is a flowchart of a method for calculating absolute time for a device to receive and transmit a message according to a second embodiment of the present invention;
fig. 3 is a flowchart of a method for calculating absolute time for a device to receive and transmit a message according to a third embodiment of the present invention;
fig. 4 is a flowchart of a method for calculating absolute time for a device to receive and transmit a message according to a fourth embodiment of the present invention;
fig. 5 is a schematic structural diagram of a device for calculating absolute time of message transmission and reception by a device according to a fifth embodiment of the present invention;
fig. 6 is a schematic structural diagram of a clock device in the sixth embodiment of the present invention.
Detailed Description
The present invention will be described in further detail with reference to the accompanying drawings and examples. It is to be understood that the specific embodiments described herein are merely illustrative of the invention and are not limiting of the invention. It should be further noted that, for the convenience of description, only some of the structures related to the present invention are shown in the drawings, not all of the structures.
Before discussing exemplary embodiments in more detail, it should be noted that some exemplary embodiments are described as processes or methods depicted as flowcharts. Although a flowchart may describe the operations (or steps) as a sequential process, many of the operations can be performed in parallel, concurrently or simultaneously. In addition, the order of the operations may be re-arranged. The process may be terminated when its operations are completed, but may have additional steps not included in the figure. The processes may correspond to methods, functions, procedures, subroutines, and the like.
Example one
Fig. 1 is a flowchart of a method for calculating absolute time of message transmission and reception by a device according to an embodiment of the present invention, where this embodiment is applicable to a case where absolute time of event message transmission and reception by a PTP clock device is calculated, and this method may be executed by a device for calculating absolute time of message transmission and reception by a device according to an embodiment of the present invention, and this device may be implemented in a software and/or hardware manner, and may be generally integrated in a processor.
As shown in fig. 1, the method of this embodiment specifically includes:
s110, obtaining the receiving and sending relative time, the reference calculation relative time and the reference calculation absolute time which correspond to the message receiving stage and the message forwarding stage of the event message respectively.
In the message receiving stage, the receiving and sending relative time is the relative time for the exchange chip to receive the event message and is actively reported to the CPU after the exchange chip receives the event message, and in the message forwarding stage, the receiving and sending relative time is the relative time for the event message to leave the exchange chip and is actively reported to the CPU after the exchange chip receives the CPU inquiry instruction.
The clock equipment receives and sends the event message, wherein the clock equipment receives the event message and transmits the event message, the message receiving time period refers to the time when the clock equipment switching chip receives the event message and the clock equipment CPU identifies the event message reported by the switching chip, and the message transmitting time period refers to the time when the clock equipment CPU completes the processing of the event message and transmits the event message to the switching chip until the event message leaves the switching chip.
The switch chip receives a message sent by an upstream device, and if the type of the message is determined to be an event message, the relative time of receiving the event message is acquired through a counter (counter) or a current time register (CurrTime) corresponding to the counter in the switch chip, and is actively reported to the CPU, for example, the relative time is added to the event message and is also reported to the CPU. The CurrTime register is a 32-bit register, has the same number of bits as the CPU, and is beneficial to the CPU to analyze and process data.
When the event message leaves the switch chip, if the switch chip receives a query instruction of the CPU, for example, a query instruction including a message Sequence number (Sequence) and a sending port number, the switch chip obtains the relative time of the event leaving the switch chip in a CurrTime register according to information in the query instruction, and actively reports the relative time to the CPU.
On the premise of knowing the relative time of the switch chip for receiving the event message and the relative time of the event message leaving the switch chip, if the absolute time (seconds/nanoseconds) of the switch chip for receiving the event message and the absolute time of the event message leaving the switch chip are to be calculated, a reference calculation relative time and a reference calculation absolute time matched with the reference calculation relative time are also required to be known.
The reference count relative time is the same as the relative time of the switch chip receiving the event message and the relative time of the event message leaving the switch chip, and is determined according to the counter, for example.
Typically, the reference calculated relative time is a time between the relative time when the event message is received by the switch chip and the relative time when the event message leaves the switch chip, and the reference calculated relative time and the reference calculated absolute time for calculating the absolute time when the event message is received by the switch chip and the absolute time when the event message leaves the switch chip may be the same or different.
And S120, calculating the transceiving absolute time matched with the transceiving relative time according to the transceiving relative time, the reference calculation relative time and the reference calculation absolute time.
After the transceiving relative time, the reference calculation relative time and the reference calculation absolute time are obtained, the transceiving absolute time matched with the transceiving relative time can be calculated.
Typically, a relative difference between the relative time of transceiving and the reference calculated relative time is calculated, an absolute time interval matched with the relative difference is determined according to a preset rule, and the absolute time of transceiving is calculated according to the absolute time of transceiving and the absolute time interval.
As a specific implementation manner of this embodiment, in the message receiving stage, the reference calculation relative time may be the relative time when the CPU receives the event message; in the message forwarding stage, the reference calculation relative time is the relative time when the CPU sends the event message to the switch chip.
Furthermore, in the message receiving stage, firstly, a relative difference value between the relative time of the CPU receiving the event message and the relative time of the exchange chip receiving the event message is calculated, then, an absolute time interval matched with the relative difference value is determined according to a preset rule, and then, the absolute time of the exchange chip receiving the event message can be calculated according to the absolute time of the CPU receiving the event message and the absolute time interval;
in the message forwarding stage, a relative difference between the relative time of the event message leaving the switching chip and the relative time of the event message sent to the switching chip by the CPU is calculated, then an absolute time interval matched with the relative difference is determined according to a preset rule, and then the absolute time of the event message leaving the switching chip can be calculated according to the absolute time and the absolute time interval of the event message sent to the switching chip by the CPU.
In the embodiment of the invention, when a PTP (precision time protocol) runs, in a message receiving stage, the relative time of the exchange chip for receiving the event message is firstly obtained, then one reference calculation relative time and the reference calculation absolute time corresponding to the reference calculation relative time are selected, and the absolute time of the exchange chip for receiving the event message is calculated according to the relative time of the exchange chip for receiving the event message, the reference calculation relative time and the reference calculation absolute time; at a message forwarding node, firstly, the relative time of the event message leaving the exchange chip is obtained, then, a reference calculation relative time and a reference calculation absolute time corresponding to the reference calculation relative time are selected, and further, the absolute time of the event message leaving the exchange chip is calculated according to the relative time reference calculation relative time and the reference calculation absolute time of the event message leaving the exchange chip. In the technical scheme, the relative time of the exchange chip for receiving the event message is reported to the CPU by the exchange chip after the exchange chip receives the event message, the relative time of the event message leaving the exchange chip is reported to the CPU by the exchange chip after the exchange chip receives the CPU inquiry instruction, and the relative time is not acquired by the CPU in a mode of actively accessing the time stamp register of the exchange chip, so that the cost of accessing the time stamp register of the exchange chip is reduced when the CPU receives and transmits the message absolute time in the computing equipment, and particularly, the cost of frequently accessing the time stamp register of the exchange chip by the CPU can be effectively reduced under the condition that a large number of PTP messages are in a burst.
Example two
Fig. 2 is a flowchart of a method for calculating absolute time for receiving and sending a message by a device according to a second embodiment of the present invention. The present embodiment is embodied based on the above embodiments, and explains in detail a method for calculating an absolute time for a device to receive and transmit a message in a message receiving stage.
In the message receiving stage, the receiving and sending relative time is the relative time of the exchange chip receiving the event message, and the reference calculation relative time is the relative time of the CPU receiving the event message.
The obtaining of the relative time for transceiving corresponding to the message receiving stage of the event message by the CPU may specifically be:
and acquiring the receiving and sending relative time added by a timestamp domain in an event message reported by the switching chip, wherein the timestamp domain is a set number of bytes added by the switching chip before an event message CRC domain.
The calculating of the transceiving absolute time matched with the transceiving relative time according to the transceiving relative time, the reference calculation relative time, and the reference calculation absolute time may specifically be:
if the reference calculation relative time is determined to be greater than the transceiving relative time, calculating a receiving relative time difference between the reference calculation relative time and the transceiving relative time, determining a receiving absolute time interval corresponding to the receiving relative time difference, and taking a difference value between the reference calculation absolute time and the receiving absolute time interval as the transceiving absolute time;
further, if it is determined that the reference calculation relative time is equal to or less than the transceiving relative time, a reception relative time difference between the reference calculation relative time and the transceiving relative time is calculated according to the maximum time duration supported by the timestamp field, the reference calculation relative time, and the transceiving relative time.
Wherein the timestamp field supports that the maximum duration is related to the number of bytes of the timestamp field;
furthermore, the calculating of the receiving relative time difference between the reference calculation relative time and the transceiving relative time according to the maximum time length supported by the timestamp domain, the reference calculation relative time and the transceiving relative time may specifically be:
calculating a first accumulated sum of a maximum duration supported by a timestamp domain and a reference calculation relative time;
and determining a difference between the first accumulated sum and the transceiving relative time as a reception relative time difference between the reference calculation relative time and the transceiving relative time.
Further, before obtaining the relative time of transceiving, the relative time of reference calculation, and the absolute time of reference calculation corresponding to the message receiving stage and the message forwarding stage of the event message, the method further includes:
determining reference calculation absolute time matched with the reference calculation relative time according to the currently stored target relative time, the target absolute time matched with the target relative time and the reference calculation relative time;
and updating the currently stored target relative time and the target absolute time matched with the target relative time according to preset conditions.
Specifically, the target absolute time is maintained by software, which may be by maintaining an absolute time of 64 bits by software, and compared with maintaining an absolute time by a 32-bit register (the time that the 32-bit register can represent is also the limited maximum number of 32 bits), the operating time for stabilizing the absolute time is enhanced, and the problem that the operating time is limited is solved.
As shown in fig. 2, the method of this embodiment specifically includes:
s210, obtaining the relative time t1 of the switch chip added in the timestamp field to receive the event message in the event message reported by the switch chip.
After the switching chip receives the message sent by the upstream device, if the message is identified as an event message, a timestamp domain with a set number of bytes is added in front of a Cyclic Redundancy Check (CRC) domain of the event message, optionally, a timestamp domain with 4 bytes is added in front of the CRC domain, and the relative time t1 when the switching chip receives the event message is added to the timestamp domain, so that the timestamp domain is reported to the CPU along with the event message.
After the CPU receives the event message, the content in the set number of bytes (4 bytes) in front of the CRC domain of the event message is intercepted by software to be used as the timestamp of the event message received by the exchange chip, thereby saving the time overhead of the CPU for frequently accessing a timestamp register.
Taking four bytes as an example, the maximum time length supported by the timestamp domain is about 4 seconds, and the time is turned over after exceeding the maximum time length supported by the timestamp domain. For example, the timestamp field supports a maximum duration of all F (1111), a next time of all 0, and then increases with the cumulative amount of time.
S220, obtaining the relative time T2 when the CPU receives the event message and the absolute time T2 when the CPU receives the event message.
When the CPU recognizes the event message, the CPU reads the current relative time and the current absolute time, that is, reads the relative time T2 when the CPU receives the event message and the absolute time T2 when the CPU receives the event message.
For example, the CurrTime register is accessed through a setting interface (TimeOfDay interface), and the current relative time in the CurrTime register (i.e., the relative time t2 when the CPU receives the event message) is read.
Meanwhile, the absolute time T2 of the event message received by the CPU, which is matched with the relative time T2 of the event message received by the CPU, may also be obtained through the TimeOfDay interface.
Specifically, the absolute time T2 is calculated from the currently stored target relative time T3, the target absolute time T3 matching the target relative time, and the relative time T2.
The target absolute time T3 is maintained by software. Specifically, a reverse rotation interrupt task may be set, where the reverse rotation interrupt task generates an interrupt when the reverse rotation indication register is set, reads the current relative time in the CurrTime register, and simultaneously reads the last saved target relative time T3 and the target absolute time T3 matching the target relative time, and then calculates the current absolute time according to the target relative time T3, the target absolute time T3, and the current relative time. The current relative time and the current absolute time are then used to correspondingly update the target relative time T3 and the target absolute time T3.
Wherein the difference between the current relative time in the CurrTime register and the target relative time t3 does not exceed the maximum time supported by one timestamp field.
When the current absolute time is calculated according to the currently stored target relative time T3, the target absolute time T3 matched with the target relative time, and the current relative time, firstly, the difference between the current relative time and the target relative time T3 is calculated, then, the absolute time interval corresponding to the difference is determined according to a preset rule, and then, the cumulative sum of the target absolute time T3 and the absolute time interval is calculated, wherein the cumulative sum is the current absolute time, namely, the absolute time T2 of the event message received by the CPU.
S230, judging whether the relative time t2 is greater than the relative time t1, if so, executing S240, and if not, executing S250.
S240, the difference between the relative time t2 and the relative time t1 is taken as the reception relative time difference between the relative time t2 and the relative time t1, and S260 is performed.
S250, calculating a first accumulated sum of the maximum time length supported by the timestamp domain and the relative time t2, and taking a difference between the first accumulated sum and the relative time t1 as a received relative time difference between the relative time t2 and the relative time t1, executing S260.
Since the concept of the maximum duration supported by the timestamp domain exists in the relative time, the relative time t2 may be greater than the relative time t1, or less than or equal to the relative time t1, and the actual difference between the two relative times does not exceed the maximum duration supported by one timestamp domain.
When the relative time t2 is greater than the relative time t1, the reception relative time difference between the relative time t2 and the relative time t1 is (t2-t 1); when the relative time t2 is equal to or less than the relative time t1, the reception relative time difference between the relative time t2 and the relative time t1 is (the timestamp domain supports the maximum duration + t2-t 1).
S260, determining a receiving absolute time interval corresponding to the receiving relative time difference, and taking the difference value between the absolute time T2 and the receiving absolute time interval as the absolute time T1 of the event message received by the exchange chip.
And then, determining a receiving absolute time interval corresponding to the receiving relative time difference according to a preset rule, wherein the absolute time T1 of the exchange chip for receiving the event message is (absolute time T2-receiving absolute time interval).
In the technical scheme, the relative time of the exchange chip for receiving the event message is reported to the CPU by the exchange chip after the exchange chip receives the event message, and the CPU does not need to obtain the relative time by actively accessing the exchange chip timestamp register, so that the cost of accessing the exchange chip timestamp register is reduced when the CPU receives and transmits the message absolute time by the computing equipment, and particularly, the cost of frequently accessing the exchange chip timestamp register by the CPU can be effectively reduced under the condition that a large number of PTP messages are in a sudden state.
EXAMPLE III
Fig. 3 is a flowchart of a method for calculating absolute time for receiving and transmitting a message by a device according to a third embodiment of the present invention. The present embodiment is embodied based on the above embodiments, and explains in detail a method for calculating an absolute time for a device to receive and transmit a packet in a packet forwarding stage.
In the message forwarding stage, the receiving and sending relative time is the relative time when the event message leaves the switching chip, and the reference calculation relative time is the relative time when the CPU sends the event message to the switching chip.
The calculating of the transceiving absolute time matched with the transceiving relative time according to the transceiving relative time, the reference calculation relative time, and the reference calculation absolute time may specifically be:
if the receiving and sending relative time is determined to be larger than the reference calculation relative time, calculating a forwarding relative time difference between the receiving and sending relative time and the reference calculation relative time, determining a forwarding absolute time interval corresponding to the forwarding relative time difference, and taking the accumulated sum of the reference calculation absolute time and the forwarding absolute time interval as the receiving and sending absolute time.
Further, if it is determined that the transceiving relative time is less than or equal to the reference calculation relative time, calculating a reception relative time difference between the transceiving relative time and the reference calculation relative time according to the maximum time duration supported by the timestamp field, the transceiving relative time, and the reference calculation relative time.
Wherein the timestamp field supports that the maximum duration is related to the number of bytes of the timestamp field;
furthermore, the receiving relative time difference between the transceiving relative time and the reference calculation relative time may be calculated according to the maximum time duration supported by the timestamp domain, the transceiving relative time, and the reference calculation relative time, specifically:
calculating a second accumulated sum of the maximum time supported by the timestamp domain and the relative receiving and sending time;
and determining a difference between the second accumulated sum and the reference calculation relative time as a reception relative time difference between the transceiving relative time and the reference calculation relative time.
Further, before obtaining the relative time of transceiving, the relative time of reference calculation, and the absolute time of reference calculation corresponding to the message receiving stage and the message forwarding stage of the event message, the method further includes:
determining reference calculation absolute time matched with reference calculation relative time according to the currently stored target relative time, the target absolute time matched with the target relative time and the reference calculation relative time;
and updating the currently stored target relative time and the target absolute time matched with the target relative time according to preset conditions, wherein the target absolute time is maintained through software.
As shown in fig. 3, the method of this embodiment specifically includes:
s310, obtaining the relative time T4 when the CPU sends the event message to the switching chip and the absolute time T4 when the CPU sends the event message to the switching chip.
When the CPU sends an event message to the switch chip, the CPU accesses the current relative time in the CurrTime register (i.e., the relative time t4 when the CPU sends the event message to the switch chip) through the TimeOfDay.
Meanwhile, the absolute time T4 of the event message sent by the CPU to the switch chip, which is matched with the relative time T4 of the event message sent by the CPU to the switch chip, can also be acquired through the TimeOfDay interface.
Specifically, the absolute time T4 is calculated from the currently stored target relative time T3, the target absolute time T3 matching the target relative time, and the relative time T4. That is, the current absolute time is calculated from the currently saved target relative time T3, the target absolute time T3 that matches the target relative time, and the current relative time.
S320, acquiring the relative time t5 when the event message leaves the exchange chip.
After the CPU sends the event message to the switch chip, it sends query information including a message Sequence number (Sequence) and a sending port number to the switch chip, so that the switch chip queries, according to the query information, a relative time t5 at which the corresponding event message leaves the switch chip in the CurrTime register.
S330, judging whether the relative time t5 is greater than the relative time t4, if so, executing S340, and if not, executing S350.
S340, taking the difference between the relative time t5 and the relative time t4 as a forwarding relative time difference between the relative time t5 and the relative time t4, S360 is performed.
S350, calculating a second accumulated sum of the maximum duration supported by the timestamp domain and the relative time t5, taking the difference value between the second accumulated sum and the relative time t4 as the forwarding relative time difference between the relative time t5 and the relative time t4, and executing S360.
Since the concept of the maximum duration supported by the timestamp domain exists in the relative time, the relative time t5 may be greater than the relative time t4, or less than or equal to the relative time t4, and the actual difference between the two relative times does not exceed the maximum duration supported by one timestamp domain.
When the relative time t5 is greater than the relative time t4, the reception relative time difference between the relative time t5 and the relative time t4 is (t5-t 4); when the relative time t5 is equal to or less than the relative time t4, the reception relative time difference between the relative time t5 and the relative time t4 is (the timestamp domain supports the maximum duration + t5-t 4).
S360, determining a forwarding absolute time interval corresponding to the forwarding relative time difference, and taking the accumulated sum of the absolute time T4 and the forwarding absolute time interval as the absolute time T5 when the event message leaves the exchange chip.
And then, determining a forwarding absolute time interval corresponding to the forwarding relative time difference according to a preset rule, wherein the absolute time T5 when the switch chip receives the event message is (absolute time T4+ forwarding absolute time interval).
For the sake of brevity, the present embodiment is not explained in detail herein, and reference is made to the aforementioned embodiments for further description.
In the technical scheme, the relative time of the event message leaving the switching chip is reported to the CPU by the switching chip after the switching chip receives the CPU inquiry instruction, and the CPU does not need to obtain the relative time by actively accessing the timestamp register of the switching chip, so that the cost of accessing the timestamp register of the switching chip is reduced when the CPU receives and transmits the message absolute time by the computing equipment, and particularly, the cost of frequently accessing the timestamp register of the switching chip by the CPU can be effectively reduced under the condition that a PTP message is in a large burst.
Example four
Fig. 4 is a flowchart of a method for calculating absolute time for receiving and sending a message by a device according to a fourth embodiment of the present invention. On the basis of the foregoing embodiment, this embodiment provides a specific implementation manner for a method for calculating an absolute time for a device to receive and transmit a packet in a packet receiving stage.
As shown in fig. 4, the method of this embodiment specifically includes:
s410, receiving a message reported by a switching chip through a packet receiving task, and judging whether the message is a 1588 event message, if so, executing S420, and if not, executing S480.
Before receiving the message through the packet receiving task, whether the cache is full can be judged, if the cache is full, the message is discarded without subsequent processing, and therefore when a large number of data messages exist, the running expense of a CPU can be reduced to a certain extent.
Specifically, the method is used for judging whether the message is a 1588 event message according to whether a frame start flag SFD is detected, and if the frame start flag SFD is detected, the message is determined to be the 1588 event message.
S420, acquiring the content of the first four bytes of the CRC field in the event message as the relative time t1 for the switch chip to receive the event message.
S430, reading the relative time T2 when the CPU receives the event message and the absolute time T2 when the CPU receives the event message through the TimeOfDay interface.
When the CPU recognizes the event message, the CPU accesses the CurrTime register through the TimeOfDay interface, and reads the current relative time in the CurrTime register, which is the relative time t2 when the CPU receives the event message.
Accessing the reversal interruption task through the TimeOfDay interface, and receiving the current absolute time calculated by the reversal interruption task according to the currently stored target relative time T3, the target absolute time T3 matched with the target relative time and the current relative time, namely the absolute time T2 when the CPU receives the event message.
S440, judging whether the relative time t2 is greater than the relative time t1, if so, executing S450, and if not, executing S460.
S450, the difference between the relative time t2 and the relative time t1 is taken as the reception relative time difference between the relative time t2 and the relative time t1, and S470 is performed.
S460, calculating a first accumulated sum of the maximum time length supported by the timestamp domain and the relative time t2, and performing S470 with a difference between the first accumulated sum and the relative time t1 as a received relative time difference between the relative time t2 and the relative time t 1.
S470, determining the receiving absolute time interval corresponding to the receiving relative time difference, and taking the difference value between the absolute time T2 and the receiving absolute time interval as the absolute time T1 of the event message received by the exchange chip.
And S480, processing the message according to the protocol of the message.
For the sake of brevity, the present embodiment is not explained in detail herein, and reference is made to the aforementioned embodiments for further description.
EXAMPLE five
Fig. 5 is a schematic structural diagram of a device for calculating absolute time of message transmission and reception by a device according to a fifth embodiment of the present invention, where this embodiment is applicable to a case of calculating absolute time of event message transmission and reception by a PTP clock device, and the device may be implemented in a software and/or hardware manner and may be generally integrated in a processor. As shown in fig. 5, the device for calculating the absolute time for transmitting and receiving a packet specifically includes: a calculation data acquisition module 510 and a calculation module 520, wherein,
a calculation data obtaining module 510, configured to obtain a relative time for transceiving, a relative time for reference calculation, and an absolute time for reference calculation, which correspond to a message receiving stage and a message forwarding stage of the event message, respectively;
in the message receiving stage, the receiving and sending relative time is the relative time for the exchange chip to receive the event message, and the event message is actively reported to the CPU through the exchange chip after being received, and in the message forwarding stage, the receiving and sending relative time is the relative time for the event message to leave the exchange chip, and the event message is actively reported to the CPU through the exchange chip after receiving the CPU inquiry instruction;
a calculating module 520, configured to calculate a transceiving absolute time matched with the transceiving relative time according to the transceiving relative time, the reference calculation relative time, and the reference calculation absolute time.
In the embodiment of the invention, when a PTP (precision time protocol) runs, in a message receiving stage, the relative time of the exchange chip for receiving the event message is firstly obtained, then one reference calculation relative time and the reference calculation absolute time corresponding to the reference calculation relative time are selected, and the absolute time of the exchange chip for receiving the event message is calculated according to the relative time of the exchange chip for receiving the event message, the reference calculation relative time and the reference calculation absolute time; at a message forwarding node, firstly, the relative time of the event message leaving the exchange chip is obtained, then, a reference calculation relative time and a reference calculation absolute time corresponding to the reference calculation relative time are selected, and further, the absolute time of the event message leaving the exchange chip is calculated according to the relative time reference calculation relative time and the reference calculation absolute time of the event message leaving the exchange chip. In the technical scheme, the relative time of the exchange chip for receiving the event message is reported to the CPU by the exchange chip after the exchange chip receives the event message, the relative time of the event message leaving the exchange chip is reported to the CPU by the exchange chip after the exchange chip receives the CPU inquiry instruction, and the relative time is not acquired by the CPU in a mode of actively accessing the time stamp register of the exchange chip, so that the cost of accessing the time stamp register of the exchange chip is reduced when the CPU receives and transmits the message absolute time in the computing equipment, and particularly, the cost of frequently accessing the time stamp register of the exchange chip by the CPU can be effectively reduced under the condition that a large number of PTP messages are in a burst.
Further, in the message receiving stage, the reference calculation relative time is the relative time when the CPU receives the event message;
in the message forwarding stage, the reference calculation relative time is the relative time when the CPU sends the event message to the switch chip.
Further, the calculation data obtaining module 510 is specifically configured to obtain, in the event message reported by the switch chip, the relative transceiving time added by a timestamp field, where the timestamp field is a set number of bytes added by the switch chip before the CRC field of the event message.
Further, the calculating module 520 specifically includes: a first computing unit and a second computing unit, wherein,
a first calculating unit, configured to, in the packet receiving stage, calculate a receiving relative time difference between the reference calculated relative time and the transceiving relative time if it is determined that the reference calculated relative time is greater than the transceiving relative time, determine a receiving absolute time interval corresponding to the receiving relative time difference, and use a difference between the reference calculated absolute time and the receiving absolute time interval as the transceiving absolute time;
a second calculating unit, configured to, in the packet forwarding stage, calculate a forwarding relative time difference between the transceiving relative time and the reference calculation relative time if it is determined that the transceiving relative time is greater than the reference calculation relative time, determine a forwarding absolute time interval corresponding to the forwarding relative time difference, and use an accumulated sum of the reference calculation absolute time and the forwarding absolute time interval as the transceiving absolute time.
Further, the first calculating unit is configured to, in the packet receiving stage, calculate, according to a maximum time supported by a timestamp domain, the reference calculation relative time, and the transceiving relative time, a receiving relative time difference between the reference calculation relative time and the transceiving relative time if it is determined that the reference calculation relative time is less than or equal to the transceiving relative time;
and in the message forwarding stage, if it is determined that the relative transceiving time is less than or equal to the reference calculation relative time, calculating a relative receiving time difference between the relative transceiving time and the reference calculation relative time according to a maximum time supported by a timestamp domain, the relative transceiving time, and the reference calculation relative time.
Further, the timestamp field supports that the maximum duration is related to the number of bytes in the timestamp field;
a first calculating unit, configured to calculate, in the packet receiving stage, a first cumulative sum of the maximum supported duration of the timestamp domain and the reference calculation relative time; determining a difference between the first accumulated sum and the transceiving relative time as a reception relative time difference between the reference calculation relative time and the transceiving relative time;
a second calculating unit, configured to calculate, in the packet forwarding stage, a second cumulative sum of the maximum supported duration of the timestamp domain and the relative time of transceiving; determining a difference between the second accumulated sum and the reference calculation relative time as a reception relative time difference between the transceiving relative time and the reference calculation relative time.
Further, the device for calculating the absolute time for the device to receive and transmit the message further includes: a reference calculation absolute time calculation module, configured to determine, before obtaining a transceiving relative time, a reference calculation relative time, and a reference calculation absolute time that correspond to a message receiving stage and a message forwarding stage of an event message, a reference calculation absolute time that matches the reference calculation relative time according to a currently stored target relative time, a target absolute time that matches the target relative time, and the reference calculation relative time;
and updating the currently stored target relative time and the target absolute time matched with the target relative time according to preset conditions.
Further, the target absolute time is maintained by software.
The device message receiving and sending absolute time calculating device can execute the device message receiving and sending absolute time calculating method provided by any embodiment of the invention, and has the corresponding functional modules and beneficial effects of the executed device message receiving and sending absolute time calculating method.
EXAMPLE six
Fig. 6 is a schematic diagram of a hardware structure of a clock device according to a sixth embodiment of the present invention, and as shown in fig. 6, the clock device includes:
one or more processors 610, one processor 610 being exemplified in fig. 5;
a memory 620;
the clock device may further include: an input device 630 and an output device 640.
The processor 610, the memory 620, the input device 630 and the output device 640 in the clock apparatus may be connected by a bus or other means, and fig. 6 illustrates the example of the connection by the bus.
The memory 620, which is a non-transitory computer-readable storage medium, may be used to store software programs, computer-executable programs, and modules, such as program instructions/modules (for example, the calculation data obtaining module 510 and the calculation module 520 shown in fig. 5) corresponding to the method for calculating the absolute time of sending and receiving a message by a device according to the embodiment of the present invention. The processor 610 executes various functional applications and data processing of the clock device by running the software program, instructions and modules stored in the memory 620, that is, the method for calculating the absolute time of the device for sending and receiving the message in the above method embodiment is implemented.
The memory 620 may include a storage program area and a storage data area, wherein the storage program area may store an operating system, an application program required for at least one function; the storage data area may store data created according to use of a clock device, and the like. Further, the memory 620 may include high speed random access memory, and may also include non-transitory memory, such as at least one magnetic disk storage device, flash memory device, or other non-transitory solid state storage device. In some embodiments, memory 620 optionally includes memory located remotely from processor 610, which may be connected to the terminal device via a network. Examples of such networks include, but are not limited to, the internet, intranets, local area networks, mobile communication networks, and combinations thereof.
The input device 630 may be used to receive input numeric or character information and generate key signal inputs related to user settings and function controls of the clock apparatus. The output device 640 may include a display device such as a display screen.
EXAMPLE seven
The seventh embodiment of the present invention further provides a storage medium containing computer-executable instructions, where the computer-executable instructions are executed by a computer processor to perform a method for calculating an absolute time for a device to receive and transmit a packet, where the method includes:
acquiring the receiving and sending relative time, the reference calculation relative time and the reference calculation absolute time which respectively correspond to the message receiving stage and the message forwarding stage of the event message;
in the message receiving stage, the receiving and sending relative time is the relative time for the exchange chip to receive the event message, and the event message is actively reported to the CPU through the exchange chip after being received, and in the message forwarding stage, the receiving and sending relative time is the relative time for the event message to leave the exchange chip, and the event message is actively reported to the CPU through the exchange chip after receiving the CPU inquiry instruction;
and calculating the transceiving absolute time matched with the transceiving relative time according to the transceiving relative time, the reference calculation relative time and the reference calculation absolute time.
Optionally, the computer executable instruction, when executed by the computer processor, may be further configured to implement a technical solution of a method for calculating an absolute time for a device to receive and transmit a packet according to any embodiment of the present invention.
From the above description of the embodiments, it is obvious for those skilled in the art that the present invention can be implemented by software and necessary general hardware, and certainly, can also be implemented by hardware, but the former is a better embodiment in many cases. Based on such understanding, the technical solutions of the present invention may be embodied in the form of a software product, which may be stored in a computer-readable storage medium, such as a floppy disk, a Read-Only Memory (ROM), a Random Access Memory (RAM), a FLASH Memory (FLASH), a hard disk or an optical disk of a computer, and includes instructions for enabling a clock device (which may be a personal computer, a server, or a network device) to execute the methods according to the embodiments of the present invention.
It should be noted that, in the embodiment of the device absolute time message sending and receiving computing apparatus, each unit and each module included in the apparatus are only divided according to functional logic, but are not limited to the above division, as long as the corresponding function can be implemented; in addition, specific names of the functional units are only for convenience of distinguishing from each other, and are not used for limiting the protection scope of the present invention.
It is to be noted that the foregoing is only illustrative of the preferred embodiments of the present invention and the technical principles employed. It will be understood by those skilled in the art that the present invention is not limited to the particular embodiments described herein, but is capable of various obvious changes, rearrangements and substitutions as will now become apparent to those skilled in the art without departing from the scope of the invention. Therefore, although the present invention has been described in greater detail by the above embodiments, the present invention is not limited to the above embodiments, and may include other equivalent embodiments without departing from the spirit of the present invention, and the scope of the present invention is determined by the scope of the appended claims.
Claims (10)
1. A method for calculating the absolute time of a device for receiving and transmitting a message is characterized by comprising the following steps:
acquiring the receiving and sending relative time, the reference calculation relative time and the reference calculation absolute time which respectively correspond to the message receiving stage and the message forwarding stage of the event message;
in the message receiving stage, the receiving and sending relative time is the relative time for receiving the event message by the switching chip and is actively reported to the CPU after receiving the event message by the switching chip, and in the message forwarding stage, the receiving and sending relative time is the relative time for leaving the switching chip by the event message and is actively reported to the CPU after receiving a query instruction for querying a message serial number and a message sending port number by the switching chip;
acquiring the receiving and transmitting relative time corresponding to the message receiving stage of the event message through a CPU, wherein the receiving and transmitting relative time comprises the following steps:
acquiring the receiving and sending relative time added by a timestamp domain in an event message reported by the switching chip, wherein the timestamp domain is a set number of bytes added by the switching chip before a CRC (cyclic redundancy check) domain of the event message;
and calculating the transceiving absolute time matched with the transceiving relative time according to the transceiving relative time, the reference calculation relative time and the reference calculation absolute time.
2. The method of claim 1, further comprising:
in the message receiving stage, the reference calculation relative time is the relative time of the CPU receiving the event message;
in the message forwarding stage, the reference calculation relative time is the relative time when the CPU sends the event message to the switch chip.
3. The method of claim 1, wherein calculating an absolute time of transceiving matching the relative time of transceiving based on the relative time of transceiving, the reference calculated relative time, and a reference calculated absolute time comprises:
in the message receiving stage, if the reference calculation relative time is determined to be greater than the transceiving relative time, calculating a receiving relative time difference between the reference calculation relative time and the transceiving relative time, determining a receiving absolute time interval corresponding to the receiving relative time difference, and taking a difference value between the reference calculation absolute time and the receiving absolute time interval as the transceiving absolute time;
in the message forwarding stage, if it is determined that the transceiving relative time is greater than the reference calculation relative time, calculating a forwarding relative time difference between the transceiving relative time and the reference calculation relative time, determining a forwarding absolute time interval corresponding to the forwarding relative time difference, and taking an accumulated sum of the reference calculation absolute time and the forwarding absolute time interval as the transceiving absolute time.
4. The method of claim 3, wherein calculating an absolute time of transceiving matching the relative time of transceiving based on the relative time of transceiving, the reference calculated relative time, and a reference calculated absolute time, further comprises:
in the message receiving stage, if the reference calculation relative time is determined to be less than or equal to the transceiving relative time, calculating a receiving relative time difference between the reference calculation relative time and the transceiving relative time according to the maximum time supported by a timestamp domain, the reference calculation relative time and the transceiving relative time;
in the message forwarding stage, if it is determined that the relative transceiving time is less than or equal to the reference calculation relative time, calculating a relative receiving time difference between the relative transceiving time and the reference calculation relative time according to a maximum time supported by a timestamp domain, the relative transceiving time and the reference calculation relative time.
5. The method of claim 4, wherein the timestamp field supports a maximum duration that is related to a number of bytes of the timestamp field;
in the message receiving stage, according to the maximum time supported by the timestamp domain, the reference calculation relative time and the transceiving relative time, calculating a receiving relative time difference between the reference calculation relative time and the transceiving relative time, including:
calculating a first cumulative sum of the maximum duration supported by the timestamp domain and the reference calculation relative time;
determining a difference between the first accumulated sum and the transceiving relative time as a reception relative time difference between the reference calculation relative time and the transceiving relative time;
in the packet forwarding stage, calculating a receiving relative time difference between the transceiving relative time and the reference calculation relative time according to the maximum time supported by the timestamp domain, the transceiving relative time and the reference calculation relative time, including:
calculating a second accumulated sum of the maximum time length supported by the timestamp field and the transceiving relative time;
determining a difference between the second accumulated sum and the reference calculation relative time as a reception relative time difference between the transceiving relative time and the reference calculation relative time.
6. The method according to claim 1, wherein before obtaining the relative time of transceiving, the relative time of reference calculation, and the absolute time of reference calculation corresponding to the message receiving stage and the message forwarding stage of the event message, respectively, further comprising:
determining reference calculation absolute time matched with reference calculation relative time according to the currently stored target relative time, the target absolute time matched with the target relative time and the reference calculation relative time;
and updating the currently stored target relative time and the target absolute time matched with the target relative time according to preset conditions.
7. The method of claim 6, wherein the target absolute time is maintained by software.
8. An apparatus for calculating absolute time for a device to transmit and receive a message, comprising:
the computing data acquisition module is used for acquiring the receiving and sending relative time, the reference computing relative time and the reference computing absolute time which respectively correspond to the message receiving stage and the message forwarding stage of the event message;
in the message receiving stage, the receiving and sending relative time is the relative time for receiving the event message by the switching chip and is actively reported to the CPU after receiving the event message by the switching chip, and in the message forwarding stage, the receiving and sending relative time is the relative time for leaving the switching chip by the event message and is actively reported to the CPU after receiving a query instruction for querying a message serial number and a message sending port number by the switching chip;
the computing data obtaining module is specifically configured to obtain, in an event message reported by the switch chip, a relative time for transceiving added by a timestamp domain, where the timestamp domain is a set number of bytes added by the switch chip before a CRC domain of the event message;
and the calculating module is used for calculating the transceiving absolute time matched with the transceiving relative time according to the transceiving relative time, the reference calculation relative time and the reference calculation absolute time.
9. Clock device comprising a memory, a processor and a computer program stored on the memory and executable on the processor, characterized in that the processor implements the method according to any of claims 1-7 when executing the program.
10. A computer-readable storage medium, on which a computer program is stored which, when being executed by a processor, carries out the method according to any one of claims 1-7.
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| CN100502314C (en) * | 2006-04-21 | 2009-06-17 | 大唐移动通信设备有限公司 | Absolute time data acquiring method and system |
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