JP2013178597A - Time management apparatus, method and program - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a time management technique with which a clock independent of others can be provided for a guest even without applying a virtual environment specific time management method to the guest.SOLUTION: A time management apparatus comprises, within a host which emulates a clock of a guest, guest clock time hold means, a cycle counter, update timing management means and guest clock time update means. The guest clock time hold means holds a guest clock time corresponding to the guest and regarding the corresponding guest. The cycle counter successively outputs a plurality of circulating counter values cyclically. The update timing management means holds an update timing table indicating a corresponding relation between the guest and a counter value indicating the timing to update the guest clock time of the guest. When output of the cycle counter becomes the counter value indicated in the update timing table, the guest clock time update means updates the guest clock time of the guest corresponding to that counter value.

Description

  The present invention relates to a technique for managing time on a computer, and more particularly to a technique for managing the time of a host and a guest in a virtual environment.

  A technique for constructing a virtual computer (hereinafter referred to as “virtual computer”) on an actual physical computer (hereinafter referred to as “physical computer”) by emulation by software is known. Thereby, the physical computer can be operated as if there are a single computer or a plurality of computers in different environments on the computer.

  A configuration including a virtual computer and a physical computer that is the operation base of the virtual computer is called a virtual environment. A base including a physical computer that operates a virtual machine is called a host, and a virtual machine is called a guest.

  In general, a computer is provided with a clock in order to acquire time and measure time, and a virtual computer needs to be provided with a clock like a physical computer.

  The clock provided in the physical computer is a clock based on the hardware. In the physical computer, apart from the hardware clock, the host OS (Operating System) manages the host time in terms of software.

  On the other hand, the clock of the virtual machine is realized not by hardware but by software. Specifically, the host OS expresses the clock of the virtual computer by emulation based on the time by the clock of the physical computer or the time by the host OS. For example, it is conceivable to perform emulation so that the clock of the virtual computer shows the same time as the clock of the physical computer.

  As described above, when the clock of the virtual computer is expressed based on the clock of the physical computer or the time by the host OS (host time), the time by the clock of the virtual computer is affected by the time of the host. For example, if the clock of the physical computer or the time by the host OS is changed, the clock time of the virtual computer also changes. In other words, the guest cannot have a time independent of the host time.

  Further, as described above, when the clock of the virtual computer is emulated so as to indicate the same time as the clock of the physical computer, a different time cannot be given to each guest when a plurality of guests are constructed.

  As described above, the fact that the guest cannot have a time independent of the host time, or that the guest cannot have a different time, restricts the use mode of the virtual environment. For example, when a plurality of virtual machines are integrated on one physical computer, such as testing a system and simulation of another system on one host, the time cannot be changed freely in each system. Inconvenience arises in testing and simulation of each system.

  On the other hand, in the technique disclosed in Patent Document 1, as a method of managing a plurality of times such as the host time and the guest time, the difference time after and before the change of each time is recorded. When a certain time is changed, other times are not affected.

JP 2004-302571 A

  However, in the technique of Patent Document 1, it is necessary to apply the time management method to each of the host and all guests. It is necessary to apply a time management method peculiar to the virtual environment to the guest OS, and it becomes difficult to incorporate a general OS that does not apply the time management method into the virtual environment as a guest OS.

  An object of the present invention is to provide a time management technique capable of providing a guest with a clock independent of others without applying a time management method specific to a virtual environment to the guest.

  A time management device according to one aspect of the present invention is a time management device for managing time in a virtual environment including a host and a guest, and corresponds to and corresponds to a guest in a host that emulates a guest clock. A guest clock time holding means for holding a guest clock time for the guest, a periodic counter for periodically outputting a plurality of cyclic counter values periodically, a guest, and a counter indicating a timing for updating the guest clock time of the guest An update timing management means for holding an update timing table indicating a correspondence relationship with the value, and when the output of the period counter reaches the counter value indicated in the update timing table, the guest clock time of the guest corresponding to the counter value Guest clock time updating means for updating.

  According to the present invention, it is possible to provide a guest with a clock independent of the others without applying a time management method specific to the virtual environment to the guest.

It is a block diagram which shows the structure of the virtual environment by this embodiment. It is a figure which shows an example of an update timing table. It is a flowchart which shows the process which updates guest clock time. It is a flowchart which shows the process which changes guest clock time. It is a flowchart which shows the process which reads guest clock time.

  A virtual environment computer system according to an embodiment of the present invention will be described in detail with reference to the drawings.

  FIG. 1 is a block diagram illustrating a configuration of a virtual environment according to the present embodiment. Referring to FIG. 1, the virtual environment 10 includes a guest 20 and a host 30. There may be a plurality of guests 20. Time management in the virtual environment 10 including the host 30 and the guest 20 will be described.

  The guest 20 has a guest time change unit 21 on the guest OS, a guest OS time management unit 22 and a guest OS time correction unit 23, and further has a virtual computer clock 24.

  The host 30 includes a guest clock time reading unit 31, a guest clock time writing unit 32, a guest OS time correction instruction unit 33, a guest clock time holding unit 34, an update time holding unit 35, an update timing management unit 36, and a period counter on the host OS. 37, a guest clock time update unit 38, a host time change unit 39, a host OS time management unit 3A, and a host OS time update unit 3B, and further includes a physical computer clock 3C.

  The physical computer clock 3C is a substantial hardware clock, while the virtual computer clock 24 is a virtual clock that the host 30 provides to the guest 20 by emulation. The host 30 has a host OS time management unit 3A that manages the host OS time, and the guest 20 has a guest OS time management unit 22 that manages the guest OS time. The host OS time management unit 3A keeps the host OS time in synchronization with the timing signal from the host OS time update unit 3B. The time of the physical computer clock 3C of the host 30 (host clock time) and the host OS time can be changed from the host time changing unit 39. Further, the time of the virtual computer clock 24 of the guest 20 (guest clock time) and the guest OS time can be changed from the guest time changing unit 21.

  The guest clock time holding unit 34 and the update time holding unit 35 in the host 30 correspond to the guest 20. When there are a plurality of guests 20, there are a plurality of guest clock time holding units 34 and update time holding units 35 correspondingly.

  The guest clock time holding unit 34 holds the guest clock time for the corresponding guest 20.

  The cycle counter 37 is a counter that counts up in synchronization with the timing signal from the host OS time update unit 3B, and periodically and sequentially outputs a plurality of counter values that circulate. More specifically, the host OS time update unit 3B outputs a timing signal that ticks 1 second, and the period counter 37 increments the counter value by 1 every second. When the counter value of the period counter 37 reaches “9”, it next returns to “0”. Since the cycle counter 37 operates with the same timing signal as that sent to the host OS time management unit 3A, the operation of the cycle counter 37 is synchronized with the host OS time management unit 3A.

  The update timing management unit 36 holds an update timing table indicating a correspondence relationship between the guest 20 and a counter value indicating a timing at which the guest clock time of the guest 20 is updated. When there are a plurality of guests 20, it is preferable to distribute the update timings of the plurality of guests 20 to a plurality of counter values as evenly as possible in the update timing table.

  FIG. 2 is a diagram illustrating an example of the update timing table. In the example of FIG. 2, there are three guests 20 named guest # 1 to # 3, and the timing of updating each guest clock time is the timing when the counter value of the period counter 37 is “0”, “3”, “4”. It is.

  When the output of the cycle counter 37 reaches the counter value shown in the update timing table held by the update timing management unit 36, the guest clock time update unit 38 corresponds to the counter value in the guest clock time holding unit 34. The guest clock time of the guest 20 is updated.

  For example, when the counter value of the period counter 37 becomes “0”, the guest clock time of the guest # 1 is updated.

  As described above, according to the present embodiment, since the host 30 individually manages the clock time of each guest 20 separately from the host time, it is possible to provide a guest clock independent of the time of the host and other guests. . Even if there are a large number of guests 20 at this time, the host 30 executes the update process by dividing the update timing of the guest clock time into a plurality of times, so that the large processing load on the processor and the host OS is short due to the update of the guest clock time. Can be prevented from concentrating on.

  The update time holding unit 35 holds a time corresponding to one cycle of the cycle counter as a default value of the update time at the next update timing of the guest clock time of the corresponding guest 20. The update time is the time added to the guest clock time at the update timing.

  When the guest clock time writing unit 32 is requested by the guest 20 to change the guest clock time of the guest 20 by a predetermined request change time, the counter value indicating the update timing of the guest 20 and the period counter in the update timing table Based on the counter value output by 37, the remaining time until the next update timing of the guest 20 is calculated, and the update change time is calculated by adding the request change time and the remaining time. The remaining time is the time from the current time to the next update timing. The difference between the counter value output from the cycle counter 37 and the update timing shown in the update timing table is the remaining time. The update change time is a time to be changed at the update timing managed by the update timing management unit 36. Further, the guest clock time writing unit 32 rewrites the update time in the update time holding unit 35 from the default value to the update time change time.

  The guest clock time update unit 38 advances the guest clock time by the update time held in the update time holding unit 35 when the update timing of the guest 20 is reached.

  Therefore, according to the present embodiment, when a change in the guest's clock time is requested, the update is executed with the change time aligned with the update timing so that the update time can be changed to the requested time. It is possible to perform an update as requested at a predetermined update timing.

  Further, when the guest clock time reading unit 31 is requested to read the guest clock time of the guest 20 from the guest 20, the counter value indicating the update timing of the guest 20 and the period counter 37 are output in the update timing table. The remaining time until the next update timing of the guest 20 is calculated based on the counter value. Furthermore, the guest clock time reading unit 31 calculates the remaining time from the sum of the guest clock time of the guest 20 held in the guest clock time holding unit 34 and the update time of the guest 20 held in the update time holding unit 35. Output the value obtained by subtraction.

  Therefore, according to the present embodiment, when the guest clock time is requested to be read, the remaining time until the next update timing is subtracted from the guest clock time at the next update timing and output. The correct guest clock time can be output no matter what time relationship is required with the update timing.

  In addition, the guest OS time correction instruction unit 33 instructs the guest to correct the guest OS time to the guest clock time in synchronization with at least a part of timing when the guest clock time of the guest clock time holding 34 is updated. .

  In the guest 20, the guest OS time correction unit 23 corrects the guest OS time according to an instruction from the guest OS time correction instruction unit.

  Thereby, the guest OS time can be periodically corrected to an accurate time.

  FIG. 3 is a flowchart showing a process for updating the guest clock time.

  Referring to FIG. 3, when the period counter 37 counts up in the host 30 (step 101), the guest clock time update unit 38 searches the update timing table of the update timing management unit 36, and the update timing matches the current counter value. The guest 20 to be extracted is extracted (step 102). Then, the guest clock time update unit 38 adds the update time 35 to update the guest clock time (step 103).

  FIG. 4 is a flowchart showing a process for changing the guest clock time.

  Referring to FIG. 4, when the guest 20 is requested to change the guest clock time from the guest time changing unit 21 to the virtual machine clock 24 in the guest 20, the change request is input from the virtual machine clock 24 to the guest clock time writing unit 32 (step 201). The guest time writing unit 32 calculates the remaining time until the next update timing of the guest 20 from the difference between the counter value indicating the update timing in the update timing table and the counter value output by the period counter (step 202). .

  Subsequently, the guest time writing unit 32 calculates the update time by adding the request change time for how much the time is advanced or delayed and the remaining time calculated in Step 202 (Step 203). The update time of the time holding unit 35 is rewritten to the change time at the time of update (step 204).

  Thereafter, when the update timing of the guest 20 comes, the update time shown in FIG. 3 is added to the guest clock time, and the guest clock time is changed.

  FIG. 5 is a flowchart showing a process for reading the guest clock time.

  Referring to FIG. 5, when there is a request for reading the guest clock time from the guest 20 to the host 30 (step 301), in the host 30, the guest clock time reading unit 31 displays a counter value indicating the update timing in the update timing table, Based on the difference from the counter value output by the cycle counter 37, the remaining time until the next update timing of the guest 20th is calculated (step 302).

  Subsequently, the guest clock time reading unit 31 calculates the remaining time calculated in step 302 from the sum of the guest clock time held in the guest clock time holding unit 34 and the update time held in the update time holding unit 35. The time is subtracted and the obtained guest clock time is output to the guest 20 (step 303).

  A state of processing when the guest clock time is updated will be described as the first embodiment. Here, a state of updating the guest clock time of guest # 1 in the update timing table of FIG. 2 is illustrated. As shown in FIG. 2, the update timing of the guest # 1 is when the count value of the period counter 37 becomes “0”.

  When the period counter 37 counts up and the counter value becomes “0”, the guest clock time update unit 38 recognizes that the update timing of the guest # 1 has come. Then, the guest clock time update unit 38 acquires the update time from the update time holding unit 35 and adds it to the guest clock time of the guest clock time holding unit 34. Here, it is assumed that the update time is 10 seconds, and the guest clock time held in the guest clock time holding unit 34 is 12:00 (12:00:00). As a result of the update, the guest clock time of the guest clock time holding unit 34 becomes 12:00:10.

  As a second embodiment, a process when the guest clock time is changed will be described. Here, the state of changing the guest clock time of guest # 1 in FIG. 2 is also illustrated. Here, it is assumed that a request is made to advance the guest clock time by one hour. That is, the request change time is 1 hour (01: 00: 00: 00).

  When the guest 20 requests the host 30 to change the guest clock time, the guest clock time writing unit 32 outputs the counter value indicating the update timing of the guest # 1 in the update timing table and the period counter 37 at that time. The difference from the current counter value is calculated as the remaining time until the next update timing of guest # 1.

  Here, the counter value indicating the update timing of guest # 1 in the update timing table is “0”. Further, it is assumed that the counter value indicated by the period counter 37 at that time is “7”. Then the remaining time is 3 seconds.

  Subsequently, the guest clock time writing unit 32 calculates the update time by adding the request change time and the remaining time, and rewrites the update time of the update time holding unit 35 to the value. Here, the request update time is 1 hour (01:00:00) and the remaining time is 3 seconds (00:00:03), so the update time change time is 1 hour 3 seconds (01:00:03). .

  Thereafter, when 3 seconds elapse and the next update timing comes, the guest clock time update unit 38 sets the update time change time (01:00:03) of the update time holding unit 35 to the guest clock time holding unit 34. The update time (01:00:03) is added to the clock time (12:00:00). As a result, the guest clock time is 13: 3 (01:00:03)

  As a third embodiment, a process when reading the guest clock time will be described. Here, the state of reading the guest clock time of guest # 1 in FIG. 2 is also illustrated.

  When the guest 20 requests the guest 30 to read the guest clock time, the guest clock time reading unit 31 outputs the counter value indicating the update timing of the guest # 1 and the period counter 37 in the update timing table. The difference from the counter value is calculated as the remaining time until the next update timing of guest # 1.

  Here, the counter value indicating the update timing of guest # 1 in the update timing table is “0”. Further, it is assumed that the counter value indicated by the period counter 37 at that time is “7”. Then the remaining time is 3 seconds.

  Subsequently, the guest clock time reading unit 31 calculates the sum of the guest clock time held in the guest clock time holding unit 34 and the update time held in the update time holding unit 35, and the obtained value The remaining time is subtracted from and the calculation result is output to the guest 20.

  Here, the guest clock time held in the guest clock time holding unit 34 is 12:00 (12:00:00), and the update time held in the update time holding unit 35 is 10 seconds (00: 00: 00: 00). 10). Therefore, the sum of the stored guest clock time and the update time is 12:10 seconds, and when the remaining time of 3 seconds (00:00:03) is subtracted from there, the guest clock time to be output is 12: 7 seconds ( 12:00:07).

  As mentioned above, although embodiment and the Example of this invention were described, this invention is not limited only to these embodiment or an Example, These embodiments are within the scope of the technical idea of this invention. The embodiments may be used in combination, or a part of the configuration may be changed.

DESCRIPTION OF SYMBOLS 10 ... Virtual environment, 20 ... Guest, 21 ... Guest time change part, 22 ... Guest OS time management part, 23 ... Guest OS time correction part, 24 ... Virtual computer clock, 30 ... Host, 31 ... Guest clock time reading part, 32 ... Guest clock time writing unit, 33 ... Guest OS time correction instruction unit, 34 ... Guest clock time holding unit, 35 ... Update time holding unit, 36 ... Update timing management unit, 37 ... Cycle counter, 38 ... Guest clock time update 39: Host time changing unit, 3A: Host OS time managing unit, 3B: Host OS time updating unit, 3C: Physical computer clock

JP 2009-064077 A

Claims (7)

A time management device for managing time in a virtual environment including a host and a guest,
In the host that emulates the guest's clock,
A guest clock time holding means for holding a guest clock time for the corresponding guest,
A cycle counter that periodically and sequentially outputs a plurality of counter values that circulate;
An update timing management means for holding an update timing table indicating a correspondence relationship between a guest and a counter value indicating a timing at which the guest clock time of the guest is updated;
When the output of the period counter reaches the counter value shown in the update timing table, guest clock time updating means for updating the guest clock time of the guest corresponding to the counter value;
A time management device. To the host,
An update time holding unit that corresponds to a guest and holds a time corresponding to one cycle of the period counter as a default value of the update time at the next update timing of the guest clock time of the corresponding guest,
When it is requested to change the guest clock time of the guest by a predetermined request change time, based on the counter value indicating the update timing of the guest in the update timing table and the counter value output by the period counter Calculating a remaining time until the next update timing of the guest, adding the request change time and the remaining time to calculate an update time change time, and setting the update time in the update time holding means to the default value And a guest clock time writing means for rewriting to the update change time from
The guest clock time update means advances the guest clock time by the update time held in the update time holding means when the guest update timing comes.
The time management apparatus according to claim 1. To the host,
When it is requested to read the guest clock time of the guest, the next time of the guest is determined based on the counter value indicating the update timing of the guest in the update timing table and the counter value output by the period counter. The remaining time until the update timing is calculated, and the remaining time is calculated from the sum of the guest clock time of the guest held in the guest clock time holding unit and the update time of the guest held in the update time holding unit Further includes a guest clock time reading means for outputting a value obtained by subtracting
The time management apparatus according to claim 2. To the host,
There is further provided guest OS time correction instruction means for instructing the guest to correct the guest OS time to the guest clock time in synchronization with at least a part of timing when the guest clock time of the guest clock time holding means is updated. And
Furthermore, to the guest,
Guest OS time correction means for correcting the guest OS time according to an instruction from the guest OS time correction instruction means;
The time management device according to any one of claims 1 to 3. There are a plurality of the guests,
The update timing table of the update timing management means is set so that update timings of the plurality of guests are distributed over a plurality of counter values.
The time management apparatus as described in any one of Claim 1 to 4. A time management method for managing time in a virtual environment including a host and a guest,
In the host that emulates the guest clock,
A guest clock time holding means for holding a guest clock time for the guest;
A period counter sequentially outputting a plurality of cyclic counter values sequentially;
An update timing management unit holding an update timing table indicating a correspondence relationship between a guest and a counter value indicating a timing for updating the guest clock time of the guest;
And a guest clock time updating unit that updates the guest clock time of the guest corresponding to the counter value when the output of the period counter reaches the counter value indicated in the update timing table. A time management program for causing a computer to manage time in a virtual environment including a host and a guest,
In the host that emulates the guest clock,
The guest clock time holding means holds the guest clock time for the guest;
A procedure in which the cycle counter periodically and sequentially outputs a plurality of counter values to be circulated;
A procedure in which the update timing management means stores an update timing table indicating a correspondence relationship between a guest and a counter value indicating a timing at which the guest clock time of the guest is updated;
A guest clock time updating means for causing the computer to execute a procedure of updating the guest clock time of the guest corresponding to the counter value when the output of the period counter reaches the counter value indicated in the update timing table; Time management program.

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