JP3746826B2 - Resource lock control mechanism - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a resource lock control mechanism for controlling exclusive acquisition of resources by an executioner, and particularly suitable for both long-term locks and short-term locks, and the problem of process dispatch faults and MP faults possessed by a spin lock method. The present invention relates to a resource lock control mechanism that can eliminate the point.
[0002]
[Prior art]
The parallel computer includes a resource lock control mechanism that enables exclusive use of resources so that processes (executors) that perform parallel operations sequentially access the resources.
[0003]
This resource lock control mechanism has two methods, a stack lock method and a spin lock method.
In the stack lock method, as shown in FIG. 10, when a resource access right acquisition request is issued from a process, the resource lock control mechanism queues the request to a stack prepared for each resource. When a resource release request is issued from a process that has given access to a resource to the process that issued the request that is queued at the top and that has finished accessing the resource, the process that is queued By removing these requests from the stack, sequential access to resources is realized. Here, “◯” in the figure indicates a request for a process waiting for access to a resource, and “●” indicates a request for a process accessing a resource.
[0004]
On the other hand, in the spin lock method, as shown in FIG. 11, a process that needs to access a resource adopts a configuration that repeatedly issues an acquisition request to the resource lock control mechanism until a resource access right can be acquired. When the resource lock control mechanism receives the request and there is no process accessing the resource pointed to by the request, the resource lock control mechanism assigns the access right to the requesting process so that the resource is sequentially accessed. Real access.
[0005]
The prior art employs a configuration in which resource lock control is executed by adopting either the stack lock method or the spin lock method according to the resource.
[0006]
[Problems to be solved by the invention]
The stack lock method has a drawback in that the processing load is heavy when used for resource exclusion control with a short exclusion time because a request is queued to the stack or a process of removing a request from the stack is executed. From now on, for example, it is applied to processing such as file access in which access to resources takes a relatively long time.
[0007]
On the other hand, the spin lock method is a loop (spin) in which a process that has acquired a resource access right continues processing while holding it for a long time, and another process repeatedly issues a resource access right acquisition request for a long time. There is a drawback of falling. Thus, for example, the present invention is applied to a process such as memory access where the exclusion time is extremely short.
[0008]
Furthermore, this spin lock method has two fault phenomena, a process dispatch fault and an MP fault. Next, these two fault phenomena will be described.
[0009]
The current computer architecture based on the simultaneous operation of a plurality of processes employs a time sharing architecture in which CPU resources are allocated to processes in a time-sharing manner.
[0010]
In other words, the CPU run right is assigned to each process in a time-sharing manner, and is sequentially / time-sharing for a plurality of processes, for example, in units of several msec to several tens of msec (time slice time). CPU running rights are assigned to each other. Then, when the process granted the CPU running right consumes a predetermined running time, the CPU running right is taken and enters a sleep state, and the CPU running right is given to a process in another sleep state. In this way, the operating system adopts a configuration in which control is performed so that a plurality of processes can use the CPU resources equally in units of time slice time.
[0011]
Under this time sharing system, the spin lock method generates a lock fault (process dispatch fault) due to process dispatch.
[0012]
That is, when the process that holds the resource access right is deprived of the CPU running right according to the time sharing rule while holding the resource access right, the resource access right is acquired for the resource as shown in FIG. The process dispatch fault occurs in that another process that requests the process repeats the spinning for at least one time slice time (which becomes longer as the number of processes increases), and wastes time.
[0013]
This process dispatch fault occurs with a higher probability as the processing time for accessing the resource becomes longer. Therefore, when the resource exclusion / occupation time becomes longer, care must be taken in using the spin lock method. In addition, since the CPU run right is given to each process in order according to the time sharing rule, this process dispatch fault causes the process that has been sleeping while retaining the access right to obtain the CPU run right again, thereby terminating the process. It will be canceled when the access right is released.
[0014]
On the other hand, recent computer systems have been equipped with a plurality of CPUs under one operating system. In such a multiprocessor system (MP), since a plurality of processes for the number of CPUs simultaneously obtain the CPU running right and operate in parallel, an MP fault occurs.
[0015]
In other words, in the case where there are two CPUs, the CPU running right is given to the process 1 and the process 2 at the same time. In this case, the process 1 and the process 2 simultaneously request the access right to the resource. When this happens, as shown in FIG. 13, an MP fault occurs in which one side falls into a loop due to a spin lock until one side releases the access right. In this way, even if the process that holds the access right to the resource is active, that is, it is not a fault due to process dispatch, other processes are kept waiting due to the configuration of the multiprocessor system. .
[0016]
Since this MP fault occurs with a higher probability as the number of CPUs increases, attention must be paid to the use of the spin lock method when the number of CPUs is large.
As described above, the stack lock method is a resource lock control method suitable for a long-term type lock, and the spin lock method is a resource lock control method suitable for a short-term type lock. Therefore, in the prior art, access to resources is long. When the time is reached, the stack lock method is used. When the access to the resource is short, the spin lock method is used. There was a problem that it was necessary to separate and use one.
[0017]
Furthermore, the spin lock method has two fault phenomena, a process dispatch fault and an MP fault. If the method using the spin lock method is fixed as in the prior art, the process dispatch fault and the MP fault There is a problem that the characteristics of the original short-term lock are remarkably impaired.
[0018]
The present invention has been made in view of such circumstances, and is suitable for both long-term locks and short-term locks, and can solve the problems of process dispatch faults and MP faults of the spin lock method. The purpose is to provide a new resource lock control mechanism.
[0019]
[Means for Solving the Problems]
FIG. 1 illustrates the principle configuration of the present invention.
In the figure, reference numeral 1 denotes a computer system, which includes one or a plurality of resources 2, a plurality of execution bodies 3 that use the resources 2, and a resource lock control according to the present invention that controls exclusive acquisition of the resources 2 by the execution bodies 3. The mechanism 4 is provided.
[0020]
The resource lock control mechanism 4 of the present invention includes a token management means 10, a waiver means 11, a judgment means 12, a stack type event waiting means 13, a first control means 14, a second control means 15, Third control means 16.
[0021]
  This token management means 10 responds to the token acquisition request from the execution body 3.Without determining whether or not the resource 2 requested by the execution body 3 is used.Only one execution body 3 is given a token.
  The abandoning means 11 monitors the token acquisition request issued by the execution body 3, and temporarily abandons the running right of the execution body 3 when the token acquisition request exceeds a specified number of times.
  In performing this processing, the abandoning means 11 is in a state in which there is no other execution body 3 that requests the resource 2 and there is no execution body 3 that already uses the resource 2 as the specified number of times. Thus, this processing is performed using the number of times corresponding to the shortest processing time from when the execution body 3 acquires the resource 2 and returns the token.
[0022]
When the token is given to the execution body 3, the determination means 12 determines whether or not the resource 2 requested by the execution body 3 is being used. The stack type event waiting unit 13 queues the resource acquisition request of the execution body 3.
[0023]
The first control unit 14 registers the resource acquisition request of the execution body 3 in the stack type event waiting unit 13. The second control means 15 gives a resource access right to the execution body 3. The third control means 16 gives the resource access right to the execution body 3 by notifying the stack type event waiting means 13 of the resource release.
[0024]
In the resource lock control mechanism 4 of the present invention configured as described above, the token management means 10 executes a process of giving a token only to one execution body 3 in response to a token acquisition request from the execution body 3. . At this time, the abandonment means 11 monitors the token acquisition request issued by the execution body 3, and when the token acquisition request exceeds the specified number of times, the execution body 3 temporarily abandons the running right of the execution body 3. Prevent falling into a long-term spin.
[0025]
  Then, when the token is given to the execution body 3, the determination means 12 determines whether or not the resource 2 requested by the execution body 3 is used.
  In response to the determination process of the determination unit 12, when the determination unit 12 determines the usage state of the resource 2, the first control unit 14 returns the token of the execution body 3 and acquires the resource of the execution body 3. The request is registered in the stack type event waiting unit 13, and the second control unit 15 determines that the determination unit 12 is not using the resource 2.And grant the resource access right to the executor 3,Returns the token of the executable 3 ofReject.
[0026]
On the other hand, when the token is given to the execution body 3 that has finished using the resource 2 by the token management means 10, the third control means 16 receives a resource acquisition request registered in the stack type event waiting means 13. , Notifies the stack type event waiting unit 13 of the release of the resource (which gives the resource access right to the execution body 3 registered at the top of the stack type event waiting unit 13), returns the token, and registers If not, return the token immediately.
[0027]
As described above, the resource lock control mechanism 4 of the present invention adopts a configuration in which the execution right 3 that has acquired the token is given the right to acquire the resource 2, and the resource 2 is exclusively acquired by the other execution body 3. If not, the access right to the resource 2 is given, and if the exclusive acquisition is made, the resource acquisition request is queued to the stack type event waiting means 13 and the spin lock method and the stack lock method are used. By adopting a hybrid configuration, it is possible to realize a resource lock control system suitable for both long-term locks and short-term locks.
[0028]
If the token cannot be acquired with the specified number of spins when adopting the configuration, the runner 3 that issues the resource acquisition request is temporarily deprived of the running right, thereby falling into a long-term spin. In addition, the lock contention caused by the MP fault is resolved, and the resource acquisition request is queued to the stack type event waiting unit 13 when the resource access right is given to the execution body 3. Even in this case, since the token is immediately returned so that the execution body 3 does not enter the sleep state while holding the token, the lock contention caused by the process dispatch fault is eliminated. Occurrence of process dispatch faults and MP faults in the lock method can also be prevented.
[0029]
DETAILED DESCRIPTION OF THE INVENTION
Hereinafter, the present invention will be described in detail according to embodiments.
As described with reference to FIG. 1, in the present invention, a resource lock control mechanism that should be called a hybrid lock mechanism that has both functions of a stack lock method and a spin lock method is prepared, and resource lock control is executed according to the prepared resource lock control mechanism. Is taken.
[0030]
As shown in FIG. 2, when a process requests a resource, each process calls the lock acquisition control mechanism 200 of the hybrid lock mechanism 20 of the present invention, acquires an access right to the resource, and then performs processing for the resource. Must-have. When the processing for the resource is finished, the lock release control mechanism 300 of the hybrid lock mechanism 20 of the present invention must be called to release the access right to the resource.
[0031]
FIG. 3 illustrates a device configuration of the hybrid lock mechanism 20 of the present invention.
As shown in this figure, the hybrid lock mechanism 20 of the present invention includes a token management mechanism 21, a spin lock mechanism 22, a process running right temporary abandonment mechanism 23, a stack type event waiting mechanism 24, and a lock holder registration management. The mechanism 25 has five mechanisms.
[0032]
Next, each of these mechanisms will be described.
As shown in FIG. 4, the token management mechanism 21 included in the hybrid lock mechanism 20 of the present invention has a role as a gateway for a process requesting resource acquisition or resource release. That is, the token management mechanism 21 has a configuration in which only one token corresponding to a bill of passage is issued. When each process enters processing for resource acquisition (lock acquisition) or resource release (lock release), The token has to be acquired, and when the processing is completed, the token must be returned.
[0033]
The token management mechanism 21 can be realized by various methods. For example, the token management mechanism 21 can be realized by using an exclusive processing instruction / check processing instruction generally provided in a normal computer.
[0034]
As shown in FIG. 5, this exclusive processing instruction executes a process of moving the contents of the first operand to the memory address indicated by the second operand. When the values before and after execution are equal, the status register is “equal”. The status information to that effect is set. If there is a processor executing this instruction, the other processor does not execute this instruction during that time, and after executing this instruction, this processor is checked by checking the status register status according to the check processing instruction. It is possible to know whether the instruction is completed exclusively. This exclusive processing instruction has the same essential meaning although there are some differences depending on the computer, such as the meanings of the first operand and the second operand are reversed.
[0035]
Using this property of the exclusive processing instruction, as shown in FIG. 6, the On value is written by the exclusive processing instruction in the flag area (set when the token is returned) in which the Off value is set as the initial value. By adopting the configuration, the token management mechanism 21 that issues a token to only one process can be realized. Needless to say, the On value / Off value may be reversed, and a memory area having a long data length may be used instead of the flag area.
[0036]
The spin lock mechanism 22 included in the hybrid lock mechanism 20 of the present invention performs processing for permitting a token acquisition request to the token management mechanism 21 issued by the process up to a specified number of times.
[0037]
When the spin lock mechanism 22 determines that the token acquisition request issued by the process has reached a specified number of times, the process run right temporary abandonment mechanism 23 included in the hybrid lock mechanism 20 of the present invention is assigned to the process run. Before the time is consumed, the operating system is instructed to give up the right to travel for the process. Upon receiving this instruction, the operating system sets the process to a predetermined position in the process dispatch queue, thereby giving up the right to travel of the process and preparing for the next process dispatch.
[0038]
This process running right temporary abandonment mechanism 23 can also be realized using a timer mechanism. In other words, in the timer mechanism, as shown in FIG. 7, when a process sets a timer value (which may be a relative value or an absolute value), the process enters a state in which CPU resources are not used, After the set timer time, the CPU is notified of a hardware interrupt called a timer interrupt, whereby the process resumes running. From now on, by using this timer mechanism, it is possible to realize the process running right temporary abandoning mechanism 23 for temporarily giving up the running right of the process. The timer value is preferably set to a value slightly larger than one time slice time of the time sharing system and smaller than two time slice times.
[0039]
The stack type event waiting mechanism 24 included in the hybrid lock mechanism 20 of the present invention is prepared for stacking resource acquisition requests from a plurality of processes in order of request and sequentially processing the resource acquisition requests. Realize service waiting. The stack type event waiting mechanism 24 can be realized by a mechanism generally equipped in a normal computer such as a Wait / Post function, an MsgSEND / MsgRCV function, or a SetLOCK function.
[0040]
The lock holder registration management mechanism 25 included in the hybrid lock mechanism 20 of the present invention manages the identifier of the process (being a lock holder) that has acquired the access right to the resource. Since there is one process that has acquired the right to access the resource, only one process identifier is managed by the lock holder registration management mechanism 25.
[0041]
FIG. 8 shows an example of a processing flow executed when the lock acquisition control mechanism 200 of the hybrid lock mechanism 20 of the present invention receives a resource acquisition request from a process. FIG. 9 shows the unlocking of the hybrid lock mechanism 20 of the present invention. An example of a processing flow executed when the control mechanism 300 receives a resource release request from a process is illustrated.
[0042]
Next, resource lock control executed by the hybrid lock mechanism 20 of the present invention will be described in detail according to this processing flow.
When the lock acquisition control mechanism 200 of the hybrid lock mechanism 20 of the present invention receives a resource acquisition request from the process, first, as shown in the processing flow of FIG. 8, using the token management mechanism 21 in step 1, Execute token acquisition processing by exclusive processing instruction. This token can be acquired by only one process as described above.
[0043]
Subsequently, in Step 2, when it is determined whether or not the process that issued the resource acquisition request has acquired a token and it is determined that the token cannot be acquired, the process proceeds to Step 3 to acquire the token by the process. It is determined whether or not the number of attempts has exceeded a predetermined number of spins, and when it is determined that the number has not exceeded, the process returns to step 1. This spin process corresponds to the process of the spin lock mechanism 22.
[0044]
On the other hand, when it is determined in step 3 that the predetermined number of spins has been exceeded, the process proceeds to step 4 where the process running right temporary abandonment mechanism 23 is activated and the running right of the process is temporarily abandoned. This run-right abandonment process prevents unnecessary spins from being executed, and by proactively promoting the elimination of lock contention events by assigning run rights to other processes. Improve the processing capacity of
[0045]
If it is determined in step 2 that the token is acquired, the process proceeds to step 5 to inquire whether or not the lock holder is registered in the lock holder registration management mechanism 25, and in step 6 the lock holder is registered. Judge whether or not. When it is determined by this determination processing that the lock holder is not registered, that is, when it is determined that there is no process that has exclusively acquired the resource having the access request, the process proceeds to step 7 to move to the lock holder. After registering the identifier of the process that acquired the token in the registration management mechanism 25, the process proceeds to step 8, and the token management mechanism 21 is used to execute the token return process by the exclusive processing instruction.
[0046]
After that, the process that has returned the token can acquire the resource exclusively by registering the process identifier in the lock holder registration management mechanism 25, and therefore executes predetermined data processing by accessing the resource. Become. Therefore, when following this processing route, the process can obtain the resource access right only by the spin lock, so that the resource access right can be obtained at a very high speed.
[0047]
On the other hand, when it is determined in step 6 that the lock holder is registered, that is, when it is determined that there is a process that exclusively acquires the resource having the access request, the process proceeds to step 9. Then, the token management mechanism 21 is used to execute the token return processing by the exclusive processing instruction, and then in step 10, the resource acquisition request issued by the process that returned the token is registered in the stack type event waiting mechanism 24.
[0048]
In this way, the resource exclusive acquisition control is executed. When this configuration is adopted, the number of spins set in step 3 is not any other process requesting resources, and has already been performed. It is preferable to use a number corresponding to a time slightly longer than the shortest processing time from when a process acquires a resource and returns a token when there is no process using the resource. With this setting, the process requesting acquisition of the token will execute the spin until the process that acquired the token returns the token without falling into a useless spin, You will be escaped from the MP fault.
[0049]
In this processing, the processing from step 5 to step 10 is the conventional stack lock method itself, but the stack lock method of the present invention is a lock realized by the spin lock mechanism 22 that executes with a limited number of spins. It is provided to cope with a lock contention that cannot be solved by a decrease in contention and a decrease in lock contention realized by the process running right temporary abandonment mechanism 23.
[0050]
The stack lock system of the present invention is provided to eliminate the possibility of long-term spin, which is a drawback of the spin lock generated directly from the spin lock mechanism 22 and the spin lock generated from the process running right temporary abandonment mechanism 23. ing. In other words, in the present invention, the stack lock method is prepared, so that the spin lock method can be interrupted halfway.
[0051]
On the other hand, when receiving the resource release request from the process, the lock release control mechanism 300 of the hybrid lock mechanism 20 of the present invention first uses the token management mechanism 21 in step 1 as shown in the processing flow of FIG. Then, the token acquisition process by the exclusive process instruction is executed.
[0052]
Subsequently, in step 2, when it is determined whether or not the process that issued the resource release request has acquired a token and it is determined that the token cannot be acquired, the process proceeds to step 3 and the token is acquired by the process. It is determined whether or not the number of attempts has exceeded a predetermined number of spins, and when it is determined that the number has not exceeded, the process returns to step 1.
[0053]
On the other hand, when it is determined in step 3 that the predetermined number of spins has been exceeded, the process proceeds to step 4 where the process running right temporary abandonment mechanism 23 is activated and the running right of the process is temporarily abandoned. This run-right abandonment process prevents unnecessary spins from being executed, and by proactively promoting the elimination of lock contention events by assigning run rights to other processes. Improve the processing capacity of
[0054]
If it is determined in step 2 that the token has been acquired, the process proceeds to step 5 where the process identifier of the release issuer registered in the lock holder registration management mechanism 25 is deleted. Determine whether a resource acquisition request is queued. When it is determined that the resource acquisition request is not queued in the stack type event waiting mechanism 24 by this determination processing, the process proceeds to Step 7 and the token management mechanism 21 is used to execute the token return processing by the exclusive processing instruction. .
[0055]
On the other hand, when it is determined in step 6 that a resource acquisition request is queued in the stack type event wait mechanism 24, the process proceeds to step 8 to notify the stack type event wait mechanism 24 of the unlocking, and the following steps 9, the identifier of the process that issued the resource acquisition request queued at the head of the stack type event waiting mechanism 24 is given to the lock holder registration management mechanism 25 (the resource access right is given to this process). ) Is registered, the process proceeds to step 7, and the token management mechanism 21 is used to execute the token return process by the exclusive process instruction.
[0056]
In this way, the resource release control is executed. However, when this configuration is adopted, the number of spins set in step 3 does not include any other process that requests the resource, and has already been a resource. It is preferable to use a number corresponding to a time slightly longer than the shortest processing time from when a process acquires a resource and returns a token in a state where there is no process using. With this setting, the process requesting acquisition of the token will execute the spin until the process that acquired the token returns the token without falling into a useless spin, You will be escaped from the MP fault.
[0057]
【The invention's effect】
As described above, the present invention adopts a configuration in which a resource acquisition right is given to a process that has acquired a token, and when the resource is not acquired exclusively by another process, the access right to the resource is acquired. In the case of exclusive acquisition, a hybrid configuration of a spin lock method and a stack lock method in which a resource acquisition request is queued on the stack is adopted. A resource lock control method suitable for both can be realized.
[0058]
And when adopting that configuration, if a token cannot be acquired with the specified number of spins, by temporarily taking away the running right of the process issuing the resource acquisition request, it will not fall into a long-term spin In addition, the lock contention caused by the MP fault is resolved, and the token is immediately returned both when the resource access right is given to the process and when the resource acquisition request is queued on the stack. In this way, the lock contention caused by the process dispatch fault is eliminated by preventing the process from entering the sleep state while holding the token. Therefore, the process dispatch fault and MP fault of the spin lock method are adopted. Occurrence can be prevented.
[Brief description of the drawings]
FIG. 1 is a principle configuration diagram of the present invention.
FIG. 2 is a diagram for explaining the use of the present invention.
FIG. 3 is a device configuration diagram of a hybrid lock mechanism.
FIG. 4 is an explanatory diagram of a token management mechanism.
FIG. 5 is an explanatory diagram of an exclusive processing instruction.
FIG. 6 is an explanatory diagram of a token management mechanism using an exclusive processing instruction.
FIG. 7 is an explanatory diagram of a process running right temporary abandonment mechanism using a timer mechanism.
FIG. 8 is a processing flow executed by the hybrid lock mechanism.
FIG. 9 is a processing flow executed by the hybrid lock mechanism.
FIG. 10 is an explanatory diagram of a stack lock method.
FIG. 11 is an explanatory diagram of a spin lock method.
FIG. 12 is an explanatory diagram of a process dispatch fault.
FIG. 13 is an explanatory diagram of an MP fault.
[Explanation of symbols]
1 Computer system
2 resources
3 Executable
4 Resource lock control mechanism
10 Token management means
11 Abandonment means
12 Judgment means
13 Stack type event waiting means
14 First control means
15 Second control means
16 Third control means

Claims (3)

In the resource lock control mechanism that controls exclusive acquisition of resources by the execution body,
In response to a token acquisition request from an execution body, token management means for giving a token to only one execution body without determining whether or not the resource requested by the execution body is used ;
Watching the issue token acquisition request to the execution body, when the token acquisition request exceeds a specified number of, performs processing Ru temporarily abandon the travel rights of the executable units, and, as the specified number of times, The shortest processing time required for an executor to acquire a resource and return a token when there is no other executor that requests the resource and there is no executor that already uses the resource using the number of times corresponding to a disposal means release to do this,
A determination means for determining whether or not a resource requested by the execution body is used when a token is given to the execution body;
A first control means for returning a token possessed by the execution body and registering the resource acquisition request of the execution body in the stack type event waiting means when the determination means determines the resource usage state;
Provided when said determination means determines the non-use state of the resource, the execution body given token from giving resource access, and a second control means for retirement return the token with the said actual line body That
Feature resource lock control mechanism. The resource lock control mechanism according to claim 1, wherein
When the token management means gives a token to the execution body that has finished using the resource, if a resource acquisition request is registered in the stack type event waiting means, the stack type event waiting means is notified of the resource release. And a third control means for immediately returning the token when the token is not registered.
Feature resource lock control mechanism. In the resource lock control mechanism according to claim 1 or 2,
The token management means includes an exclusive processing instruction that writes a specified data value in a specified memory area when a token acquisition request is issued from the execution body, and a data value in the memory area that differs before and after the execution of the exclusive processing instruction. To execute the exclusive grant of the token using the check processing instruction to check whether or not
Feature resource lock control mechanism.

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