JPH1049309A - Scsi/tcq control system - Google Patents

Abstract

PROBLEM TO BE SOLVED: To sufficiently derive the performance of a magnetic disk drive and to speed up processing without making a request exceeding the performance by setting the upper-limit value of the number of issued tagged command queuing(TCQ) commands in device ID units. SOLUTION: An information processor 1 which is connected to magnetic disk drives 5 and 6 through a SCSI bus 7 makes the TCQ command issue of the SCSI control driver 3 of an OS 2 efficient and consists of a command issue processing part 33, a command end processing part 34, and a current counter 31 and a save counter 32 provided in a memory 4. The current counter 31 stores the number of commands which are issued by the SCSI control driver 3 and being executed in ID units and the save counter 32 stores a permissible upper-limit value in ID units. The command issue processing part 33 compares the issue number with the upper-limit value to previously detect the issue of TCQ commands exceeding the upper-limit value and enqueue them. The command end processing part 34 subtracts the issue number in end response and sets the current issue num ber to the upper-limit value of the save counter 32 in queue-full response.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a SCSI / TCQ control method, and more particularly to a SCSI / TCQ control method for an information processing device connected to a plurality of magnetic disk devices having a TCQ function via a SCSI bus.

[0002]

2. Description of the Related Art TCQ (Tagged Command)
The queuing function is a function in which the magnetic disk device receives a plurality of commands, temporarily stores them with a tag, temporarily executes them, and responds by sequentially executing the commands. The access speed of the magnetic disk device is limited, Since it takes time to respond, it is provided especially to improve the processing efficiency of an information processing apparatus that performs multitask processing.

SCS used by connecting to a SCSI bus
The I magnetic disk device (hereinafter, simply referred to as a magnetic disk device) is supplied from a plurality of device manufacturers with different device sizes, and can be accepted by the magnetic disk device even if it has a TCQ function. The maximum number of TCQ commands varies depending on the device scale and the device manufacturer.

A magnetic disk device having a TCQ function is:
When a TCQ command is transferred from a higher-level information processing device, the transferred TCQ command is received and stored in a memory, and an end response is returned at the end of processing until the maximum number of TCQ commands of the magnetic disk device is reached. If the maximum number of TCQ commands has been stored in the memory, the queue full response (Queueing Full Response)
Status), and rejects acceptance of the transferred TCQ command.

[0005] In the conventional SCSI TCQ control method of an information processing device for controlling a plurality of magnetic disk devices having a TCQ function connected via a SCSI bus, the maximum number of TCQ commands that the magnetic disk device can accept is limited to the device. In consideration of the fact that the size and the device manufacturer differ, and that the access performance to the magnetic disk device deteriorates when the queue full response occurs frequently, an upper limit is set for the number of TCQ commands issued to one magnetic disk device, In general, a method of selecting the smallest value of the maximum number of TCQ commands among the magnetic disk devices connected to the SCSI bus as this upper limit value and having it as a unique value common to all magnetic disk devices has been common.

[0006]

The above-described conventional SCS
The problem with the I • TCQ control method is that the upper limit of the number of TCQ commands issued to the magnetic disk device is set to a minimum value as a fixed value common to all magnetic disk devices. Despite having room to accept, the issue of the TCQ command is restricted, and the performance of the magnetic disk device is not fully exploited.

An object of the present invention is to set the upper limit of the number of TCQ commands issued to a magnetic disk drive (SCSI I / O).
D) By automatically setting and managing the same as the maximum number of TCQ commands in units, the performance of each magnetic disk device connected to the SCSI bus can be sufficiently extracted, and the occurrence of a queue full response can be achieved without requesting a performance higher than the performance. SCSI / TCQ that eliminates wasted processing and speeds up processing
It is to provide a control method.

[0008]

A SCSI-T according to claim 1
The CQ control method is based on the TC of an information processing device connected to a plurality of magnetic disk devices having a TCQ function via a SCSI bus.
In the SCSI / TCQ control method for controlling the issuance of Q commands, a current value storage means for storing the number of TCQ commands being executed for each device ID, and an upper limit value for storing the number of TCQ commands permitted to be issued for each device ID Means for adding a TCQ command by adding 1 to the storage value of the current value storage means when the storage value of the current value storage means does not reach the upper limit of the upper limit storage means for each device ID unit A command issuance processing unit that waits for issuance when the storage value of the storage unit reaches the upper limit value of the upper limit storage unit;
Command termination processing means for receiving a termination report for the Q command and subtracting 1 from the stored value of the current value storage means.

The SCSI / TCQ control method according to claim 2 is as follows.
2. The SCSI / TCQ control method according to claim 1, wherein said command issuing processing means adds a 1 to a value stored in said current value storage means when said effective upper limit value is not stored in said upper limit value storage means. A command issuing function, wherein the command termination processing means stores the storage value of the current value storage means as the upper limit value of the upper limit value storage means when the queue completion response is received from the magnetic disk device, and thereafter the It is characterized by having a function of subtracting 1 from the value stored in the value storage means.

[0010] The SCSI / TCQ control method according to claim 3 is as follows.
In the SCSI / TCQ control method according to claim 1 or 2, the upper limit value storage means is constituted by an electrically rewritable nonvolatile memory.

[0011]

Next, embodiments of the present invention will be described with reference to the drawings.

FIG. 1 is a block diagram showing the configuration of one embodiment of the present invention.

As shown in FIG. 1, the SCSI / TCQ control method of the present embodiment uses the information processing device 1 connected to the magnetic disk devices 5 and 6 of different manufacturers via the SCSI bus 7 in the OS2. SCSI control driver 3
Is for improving the efficiency of issuing TCQ commands to the magnetic disk devices 5 and 6 having the maximum number of TCQ commands, and the command issue processing unit 33 and the command end processing unit 34 included in the SCSI control driver 3. When,
It comprises a current counter 31 and a save counter 32 provided in the memory 4.

The current counter 31 manages the number of executing TCQ commands issued by the SCSI control driver 3 for each magnetic disk device (SCSI ID), and issues a TCQ command for each magnetic disk device. Then, 1 is added to the issued number of the corresponding ID, and when the processing is completed, 1 is subtracted from the issued number.

The save counter 32 stores the upper limit of TCQ commands that can be issued in units of magnetic disk devices (SCSI IDs). In this embodiment, the maximum number of TCQ commands that can be accepted by each magnetic disk device is automatically set. Is set.

The command issuance processing section 33 is a means for performing processing for issuing a TCQ command to the magnetic disk devices 5 and 6, and uses the current counter 31 and the save counter 32 to exceed the maximum number of TCQ commands. It has a function to detect the issuance of a TCQ command in advance and wait for it to prevent useless TCQ command issuance and exchange of queue full responses.

The command termination processing section 34 receives the response to the TCQ command from the magnetic disk devices 5 and 6 and performs termination processing. The command termination processing section 34 receives a queue full response in addition to the normal processing of subtracting the number of current counters 31 issued. A function of setting the maximum number of TCQ commands in the save counter 32 when the timer is turned on.

FIG. 2 is a flowchart showing the processing procedure of the command issuing processing unit 33.

The SCSI control driver 3 initializes both the current counter 31 and the save counter 32 at the time of the initialization, and sets a state in which valid values (other than 0) are not set for the number of issued IDs and the upper limit value for all IDs. After that, the operation starts.

When the SCSI control driver 3 issues a TCQ command to the magnetic disk devices 5 and 6, the command issuance processing unit 33 sets the upper limit area of the ID corresponding to the magnetic disk device to which the command is to be issued in the save counter 32. It is checked whether or not a valid value is set in (step S1). If a valid value is not set (upper limit value = 0) (step S2), 1 is added to the value of the issue number area of the corresponding ID in the current counter 31, and a TCQ command is issued to the magnetic disk device. Is issued (step S3).

As a result of the check in step S2, if a valid value is set in the save counter 32, the number of issued IDs (C) of the corresponding ID in the current counter 31 and the number of Comparing with the upper limit value (S) (step S4), if the issued number (C) of the current counter 31 is small (C <S) (step S5), the process proceeds to step S3 and the save counter 32
In the same processing as when the valid value is not set in the command, 1 is added to the issued number (C) of the current counter 31 and a TCQ command is issued to the magnetic disk device.

As a result of the comparison in step S5, if the number of issues (C) of the current counter 31 is equal to the upper limit (S) of the save counter 32 (C = S), the process waits for the issuance of a TCQ command to the magnetic disk device. (Step S6). The issuance of this TCQ command is waited until a completion report is generated from the magnetic disk device of the corresponding ID, the number of issued IDs of the current counter 31 is reduced by the command completion processing unit 34, and the number is reduced below the upper limit of the save counter 32. It is.

FIG. 3 is a flowchart showing the processing procedure of the command end processing unit 34.

The command end processing unit 34 checks the end status returned from the magnetic disk device at the time of reporting the TCQ command end (step S11). If the response is a queue full response (step S12), the current counter 3
1 is stored in the upper limit area corresponding to the same ID of the save counter 32, and the TCQ command issued to the command Is notified and a reissue process is instructed (step S13). Then, the corresponding ID of the current counter 31
Is subtracted from the issuance number (step S14). If the determination in step S12 is not a queue full response but is a normal end, the process immediately proceeds to step S14 and ends.

As described in detail above, according to the SCSI / TCQ command control method of this embodiment, when the current counter 31 and the save counter 32 are started from the initialized state, once the queue full response is received, the magnetic disk The maximum number of TCQ commands of the apparatus is automatically set as an upper limit value in the save counter 32. Thereafter, before issuing the TCQ command, a queue full state is detected and the issuing of the TCQ command is waited for. As a result, the performance of each magnetic disk device is maximized, and unnecessary processing does not occur because requests that exceed the performance of the magnetic disk device are not made. It becomes possible.

In the above description of the embodiment, the current counter and the save counter are provided in the same memory, and are started from a state where both are initialized. On the other hand, if the current counter is provided in a normal RAM, but the save counter is provided in an electrically rewritable nonvolatile memory (EEPROM), the upper limit once stored is saved even when the power is turned off. Only the current counter needs to be initialized and started, and if there is a change in the configuration of the magnetic disk device, only the upper limit value of the ID required for the save counter needs to be initialized.

In the above embodiment, the upper limit value of the save counter is automatically set to the maximum number of TCQ commands of the device. However, the upper limit value of the save counter is set in advance according to the characteristics of the magnetic disk device connected to the SCSI bus. Even if a table in which an upper limit value is set for each ID is created and stored in an external storage device, and is read into the memory at the time of startup, it is troublesome to make a correction when the device configuration is changed, but the same effect is obtained. Is obtained. The table may be created not in the external storage device but in an EEPROM in the device, and the correction may be made only when the device configuration is changed.

[0028]

As described above, the SCSI of the present invention
The TCQ control method uses an ID of the upper limit of the number of TCQ commands issued to the magnetic disk device connected to the SCSI bus.
Since the management is performed in units, the performance of the magnetic disk device can be sufficiently exploited, and unnecessary requests can be prevented from being made more than the performance of the magnetic disk device. This has the effect of making it possible to speed up the processing for. Also, since the upper limit value for each magnetic disk device can be automatically set during use, the above effects can be exhibited without being conscious of the performance of various magnetic disk devices connected to the bus. Becomes

[Brief description of the drawings]

FIG. 1 is a block diagram showing a configuration of an embodiment of the present invention.

FIG. 2 is a flowchart showing a processing procedure of a command issuance processing unit of FIG. 1;

FIG. 3 is a flowchart showing a processing procedure of a command end processing unit of FIG. 1;

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Information processing apparatus 2 OS 3 SCSI control driver 4 Memory 5, 6 Magnetic disk device 7 SCSI bus 31 Current counter 32 Save counter 33 Command issue processing part 34 Command end processing part

Claims (3)

[Claims] An information processing device connected to a plurality of magnetic disk devices having a TCQ function via a SCSI bus.
In the SCSI / TCQ control method for controlling command issuance, current value storage means for storing the number of TCQ commands being executed in the magnetic disk device for each device ID, and the magnetic disk device being capable of receiving the magnetic disk device for each device ID An upper limit value storage unit for storing an upper limit value of the TCQ command; and a storage value of the current value storage unit for each device ID only when the storage value of the current value storage unit does not reach the upper limit value of the upper limit value storage unit. Command issuing processing means for waiting for the TCQ command to be issued when the stored value of the current value storage means reaches the upper limit of the upper limit value storage means;
A SCSI / TCQ control method, comprising: command completion processing means for subtracting 1 from the value stored in the current value storage means when receiving a completion report for the TCQ command from the magnetic disk device in D units. 2. The command issuing processing means unconditionally adds 1 to a value stored in the current value storage means and issues a TCQ command when a valid upper limit value is not stored in the upper limit value storage means. The command termination processing means stores the stored value of the current value storage means as the upper limit value in the upper limit value storage means when receiving a queue full response from the magnetic disk device, and thereafter stores the current value. 2. The SCSI / TCQ control system according to claim 1, further comprising a function of subtracting 1 from the stored value of the means and instructing the command issuing processing means to reissue a TCQ command. 3. The SCSI device according to claim 1, wherein said upper limit value storage means comprises an electrically rewritable nonvolatile memory.
TCQ control method.