JPH0816456A - Resource management device - Google Patents

Abstract

PURPOSE:To increase the flexibility and improve the throughput of the whole system by acquiring a common resource in common exclusively to a read system process, and acquiring the common resource exclusively to a write system process. CONSTITUTION:An exclusive control part 10 has P instruction parts which declare resource acquisition to a read system and a write system respectively and V instruction parts which declare the release of resources; and the read system P instruction part 20 acquires the common resource in common exclusively to the read system process and the write system P instruction part 30 acquires the common resource exclusively to the write system process. The resource acquisition priority 7 of a process control block 6 stored in the memory 1 is assigned to the read system process and write system process and resource acquisition order is determined on the basis of the priority; and the P instruction parts 20 and 30 of the read and write systems acquires the resources of the respective processes and the V instruction parts 40 and 50 release the resources respectively.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to software for a computer system, and more particularly to a resource management system for resources that are commonly accessed by a plurality of processes and the type of access is divided into read type and write type.

[0002]

2. Description of the Related Art Structures of exclusive control and shared exclusive control described in "Concept of operating system" (co-authored by JL Peterson and A. Silvershatz) will be described as prior art. In a system in which a plurality of processes operate in parallel, it is necessary to perform exclusive control on data commonly accessed by the processes. Furthermore, shared exclusive control is required for shared data such as files and records. For data objects such as files and records, there are processes that only read the contents, and processes that update (read and write) the contents. A process that only reads is called a read process, and other processes are called a write process to distinguish them. Data inconsistency does not occur when two read-related processes access the shared data target at the same time, but another write-related process and another process (either read or write-related) simultaneously share the shared data target. Accessing is confusing. In order to prevent such confusion, the write system needs to access the shared data exclusively. This resource management method is called shared exclusive control.

Conventional shared exclusive control is implemented using an exclusive control mechanism. Before explaining the shared exclusive control method, the shared data exclusive control method will be described. A semaphore introduced by Dijkstra is known as a method of this exclusive control. Operations on semaphores are performed only by two standard primitives, the P and V instructions. Since the P instruction and the V instruction need to be executed as an indivisible unit, they are executed in the interrupt prohibited section. The process executes the P instruction for the semaphore to access the resource, and when the access is completed, executes the V instruction for the semaphore to perform the exclusive control of the resource. That is, the processing of the P instruction is a declaration of resource acquisition, and V
The processing of an instruction is a declaration of resource release. It is said that the process is locking the resource or the semaphore or acquiring the semaphore from the execution of the P instruction to the execution of the V instruction.

FIG. 25 shows the structure of a semaphore. Memory 1
A semaphore management table 180 and a process control block (hereinafter referred to as a PCB) 183 are stored above. The semaphore management table 180 has areas of a pointer 181 to a list of processes waiting for acquisition of a semaphore and a semaphore value (integer value) 182. PCB18
3 includes a pointer 184 to a PCB for forming a resource acquisition waiting process list. The queue process list is more commonly implemented as a queue, and any queue scheme (FIFO, scheduling priority, etc.) may be used. The exclusive control unit 18 includes a P command unit 190 and a V command unit 200, and uses the data in the memory 1 to operate the semaphore.

FIG. 26 shows a flow chart of the P command portion (lock or acquisition) of the semaphore, and FIG. 27 shows a flow chart of the V instruction portion (unlock or release) processing. In the P command part, the value of the semaphore is first decremented by 1 (S1901), and if the result is not a negative value of the semaphore (S1902, No), the process calling this P command part can acquire the resource. , And ends the process. If the result of S1901 is a negative value of the semaphore (S1902, Yes), the process must wait for resource acquisition, so the PCB of the process is inserted into the resource acquisition wait list (S1).
903), the process itself is put into a sleep state and execution is suspended (S1904). On the other hand, in the V instruction part, in FIG. 27, the value of the semaphore is first incremented by 1 (S2001), and as a result, the value of the semaphore is not 0 or less (S200).
(2, No), since there is no process waiting for resource acquisition, the process is terminated. As a result of S2001, if the value of the semaphore is 0 or less (S2002, Yes
s) Since there is a process waiting for resource acquisition, one PCB is taken out from the head of the waiting process list (S2003), and execution of the process of the PCB is restarted (S2004). The two instructions of step S1904 and step S2004 are provided by the operating system as basic system calls.

Next, a conventional shared exclusive control using the semaphore will be described. The reading process shares the following data structure. A, B: semaphore; readcnt: integer type variable; initial values of semaphore A and semaphore B are 1, read
The initial value of cnt is 0. readcnt is a variable for counting the number of read-related processes (processes for reading shared data) currently accessing the shared resource. The semaphore A is used to guarantee mutual exclusion of readcnt when updating the value of readcnt. The semaphore B is used for mutual exclusion between a read process and a write process (process for updating shared data) and mutual exclusion between a write process.

The general structure of the reading process is as follows. P (A); readcnt = readcnt + 1; if (readcnt == 1) P (B); V (A);・ ・ ・ ・ ・ ・ ・ ・ P (A); readcnt = readcnt-1; if (readcnt == 0) V (B); V (A); On the other hand, the general structure of the writing process is as follows. become. P (B); ... Writing is executed.・ ・ ・ ・ ・ ・ ・ ・ V (B);

In the case of the write-related process, the exclusive control is the same as the conventional one. If no read process is accessing the shared data, the process is as follows. First, the first process acquires semaphore A and r
Add 1 to eadcnt. However, at this time, 0 is included in readcnt as an initial value. Then rea
Since dcnt is equal to 1, semaphore B is acquired. Then release semaphore A. After this, the first read-related process starts access to the shared data and the read is executed. Next, when the second read process tries to access the shared data, the semaphore A is first acquired. Since the semaphore A has already been released by the first reading process at this time, it can be acquired. Then add 1 to readcnt, and rea
The value of dcnt is 2. At this time, since readcnt is not 1, the process of acquiring the semaphore B is not performed and the semaphore A is released and the reading is executed. The same applies when the third read-related process accesses shared data. In this way, in the case of a read process that accesses shared data for the first time, readcnt is always 1, so semaphore B is acquired. If one reading process can acquire the semaphore B, another reading process newly acquires the semaphore B.
Can be read without having to wait for acquisition. Here, it is assumed that n reading processes are executing reading. When one of them has finished reading, the semaphore A is acquired, 1 is subtracted from readcnt, and the number of read-related processes currently accessing the shared data is reduced by 1. If this read process is the last one, readcnt becomes equal to 0, so the semaphore B is released at this time. Then release semaphore A. In this way, when only the read-related processes access the shared data, n read-related processes can simultaneously access the shared data. At this time, only the first reading process acquires the semaphore B, and the last reading process releases the semaphore B. Also, at this time, even if the writing process attempts to access the shared data and acquires the semaphore B, the reading process cannot use the semaphore B because the reading process already uses the semaphore B, and the writing process releases the semaphore B. I will wait.

If one write process is accessing shared data and n read processes are waiting, one read process is kept waiting by semaphore B and the other n-1. Each reading process is kept waiting by the semaphore A. In addition, when the write-related process finishes accessing the shared data, V
When (B) is executed, the execution of the read system waiting for the semaphore B or the one writing process waiting for the semaphore B is resumed. At this time, when the execution of the reading process is restarted, the processing of the n-1 reading processes waiting in the semaphore A is sequentially restarted.

[0010]

In the shared exclusive control method using the conventional semaphore, if the read process once accesses the shared data, the read process group unconditionally changes to the shared data. It becomes accessible. At this time, the writing process trying to access the shared data must wait until all the reading processes accessing the shared data are gone. Therefore, there is a problem that the access to the shared data of the writing process is delayed by the reading process group for an indefinite time. This problem can be prevented by designing so that the resource lock request of the reading process does not occur continuously for a long time, but such a design is quite difficult, and development efficiency and There is a problem that it also takes a debugging load.

As pointed out above, the present invention has been made in order to prevent the write-related process from falling into the resource allocation starvation state, and can guarantee the development efficiency of application design and the normal operation of the system. An object of the present invention is to provide a resource management device that improves the throughput of the entire system and performs flexible exclusive control.

[0012]

A resource management apparatus for shared resources according to the present invention has the following elements. (A) Exclusive with a read instruction unit that executes shared acquisition of a shared resource for a read process and a write instruction unit that executes acquisition of a shared resource exclusively for a write process (B) control means for causing the read-related process to execute the read-related command part of the exclusive control part and causing the write-related process to execute the write command part of the exclusive control part.

The control means assigns resource acquisition priorities to the reading process and the writing process,
It is characterized in that the order of resource acquisition by the exclusive control unit for the read process and the write process is determined based on the resource acquisition priority.

It is characterized in that a process-specific attribute value is used as the resource acquisition priority.

The process scheduling priority is used as the attribute value peculiar to the process.

It is characterized in that the number of already occupied resources of the process is used as the attribute value peculiar to the process.

The feature is that the main memory occupation capacity of the process execution image existing on the main memory is used as the attribute value peculiar to the process.

C of the process as a process-specific attribute value
It is characterized by using PU usage time.

It is characterized in that the processing importance of the process is used as the attribute value unique to the process.

It is characterized in that the value of the resource acquisition priority can be explicitly designated at the time of resource acquisition request.

A feature is provided in which means for registering the resource acquisition priority in advance for each process for each resource is provided.

The resource occupancy time of the process is used as the value of the resource acquisition priority.

It is characterized in that the value of the resource acquisition priority is determined by a combination of arbitrary scales.

A plurality of types of resource acquisition priority setting methods are provided, and means for selecting a resource acquisition priority setting method for each resource is provided.

[0025]

In the present invention, the control means causes the read system process to execute the read system command section of the exclusive control section,
Causes the write process to execute the write command unit of the exclusive control unit. Therefore, different controls can be realized in the reading process and the writing process.

In the present invention, the control means assigns the resource acquisition priority to the reading process and the writing process. Therefore, the read instruction unit and the write instruction unit of the exclusive control unit can determine the resource acquisition order for the read process and the write process based on the resource acquisition priority. In addition, the resource acquisition starvation state of the writing process can be avoided.

In the present invention, a process-specific attribute value is used as the resource acquisition priority.

In the present invention, the scheduling priority of a process is used as a process-specific attribute value.

In the present invention, the number of resources already occupied by the process is used as the attribute value unique to the process.

In the present invention, the main memory occupation capacity of the process execution image existing on the main memory is used as the attribute value peculiar to the process.

In the present invention, the CPU usage time of a process is used as a process-specific attribute value.

In the present invention, the processing importance of the process is used as the attribute value unique to the process.

In the present invention, the value of resource acquisition priority can be explicitly specified at the time of resource acquisition request according to each resource.

In the present invention, means for registering the resource acquisition priority for each process in advance according to each resource is provided.

In the present invention, the process resource occupation time is used as the value of the process resource acquisition priority for each resource registered in advance.

In the present invention, the value of the resource acquisition priority is determined by a combination of arbitrary scales.

In the present invention, a plurality of types of resource acquisition priority setting methods are provided, and the resource acquisition priority setting method is selected for each resource.

[0038]

【Example】

Example 1. The basic configuration of this embodiment is shown in FIG. Reference numeral 1 denotes a memory, and the memory 1 stores a semaphore management table 2 and a process control block (hereinafter referred to as a PCB) 6. In the semaphore management table 2, a waiting process list pointer 181 as a pointer to a list of processes waiting to acquire a semaphore, and a semaphore value indicating the number of processes waiting to acquire a semaphore (also referred to as value).
182 and a variable readcounter3 for counting the number of read processes that are accessing the resource,
It is composed of a pointer (PTR) 4 to a write-related process having the highest resource acquisition priority among the processes waiting for semaphore acquisition, and a lock mode (read mode / write mode) 5 of the process acquiring this semaphore. . The initial value of the semaphore value 182 is 1, readco
The initial value of unter3 is 0. Null if PTR4 points to nothing. In the PCB 6, the next pointer 184 as a pointer to the PCB for forming the waiting process list, the resource acquisition priority 7 which is the process resource acquisition priority storage area, and the resource lock mode (read mode / write mode) storage There is an area resource lock mode 8. The resource acquisition waiting process list is a process control block (PC
B) 6 for resource acquisition priority 7 in descending order of PCB next
It is a list linked using the t pointer 184. The exclusive control unit 10 includes a read system P command unit 20, a write system P command unit 30, a read system V command unit 40, and a write system V command unit 50. Since the P instruction part and the V instruction part need to be executed as an indivisible unit as in the conventional case, they are executed in the interrupt prohibited section.

The feature of this embodiment is that the read control system and the write system have a P command section and a V command section, respectively, whereas the prior art example had only the P command section and V command section. is there. Also, in the semaphore management table 2,
This is that dcounter 3, PTR 4 and lock mode 5 are provided, and PCB 6 is provided with resource acquisition priority 7 and resource lock mode 8. P command part in the first embodiment,
In both the V command section, a semaphore (S) and a lock mode (RorW) are designated as arguments. The initial value of the semaphore is 1, R indicates Read and W indicates Write. Therefore, in the shared exclusive control method using the conventional semaphore,
Two semaphores were used at one time, but the feature is that they are controlled by one semaphore.

FIG. 2 is an outline of the read system P command section 20 according to the first embodiment. First, the resource lock mode 8 of the PCB of the process that called the P command part is set to the read mode (S201). Next, as in the conventional P command section, in step S1901, the semaphore S val
The value of ue is decremented by 1 and the v of the semaphore S is incremented in S1902.
Check the value of value <0. The judgment in S1902 is N
If the value is o, it indicates that the read process that called this process can acquire the resource, so the value of the variable readcounter that counts the number of read processes that lock the semaphore is incremented by 1 (S207),
The current lock mode 5 of the semaphore is set to the read mode (S208), and the process ends.

If the determination in S1902 is Yes,
Indicates that there is a possibility of waiting for resource acquisition. This is because, if the resource is occupied by the writing process, the reading process that newly issued the resource acquisition request needs to wait for the resource acquisition. On the other hand, if the resource is occupied by the reading process, the reading process that newly issued the resource acquisition request may acquire the resource as it is according to the resource acquisition priority or may need to wait for the resource acquisition. is there. As described above, in the P command part of the read-related process, it is necessary to distinguish the processing depending on the lock mode of the semaphore S, and therefore the lock mode of the semaphore S is determined in S202.

If the current lock mode is not the write mode (S202, No), the process proceeds to S203.
In S203, it is determined whether or not the PTR of the semaphore S is Null, that is, there is no PCB pointed to by the PTR. If there is no (S203, Yes), the process proceeds to S205.
If the determination in S203 is No, the resources of the read process that called this process (requested the resource lock) and the write process with the highest resource acquisition priority among the processes waiting to acquire the same resource The acquisition priorities are compared (S204). As a result of step S204, if the resource acquisition priority of the reading process is high (Yes
s) Since it is not necessary to wait for the acquisition of resources, the value of the semaphore updated in step S1901 is returned to the original value (S205), then steps S207 and S208 are executed, and the process ends. On the other hand, if the resource acquisition priority of the write process is high (S204, No), the read process that made the resource lock request is inserted into the resource waiting process list in the resource acquisition priority order (descending order) (S20).
6) Then, the execution is blocked until the resource is released in the sleep state (S1904).

If the current lock mode is the write mode as a result of the determination in step S202 (S202,
Yes), executing steps S206 and S1904 to block the read process that has made the resource lock request until the resource is released. When the resources are released and the resources can be acquired, the dormant read-related process becomes the executable state, and the process is restarted from S207. In the above process, in S204, the write process indicated by the PTR is compared with the resource acquisition priority of the read process to determine whether the process is added to the waiting process list or executed. The feature is that it avoids the resource allocation starvation.

Next, referring to FIG. 3, the write system P command section 30
The processing flow of is described. First, the resource lock mode 8 of the PCB of the process that called the P command part is set to the write mode (S301). Then, the value of the value of the semaphore S is decremented by -1 (S1901) in the same manner as in the conventional P command unit, and the value of the value of the semaphore S <0 is determined (S1902). If the determination in S1902 is No, it indicates that the write-related process that called this process can acquire resources, and sets the current lock mode 5 of the semaphore to the write mode (S30
3) End the process. If the determination in step S1902 is Yes, it indicates that it is necessary to wait for resource acquisition. In S204, the resource acquisition priority of the write-related process having the highest resource acquisition priority among the processes waiting for acquisition of the same resource and the write-related process that called this processing is compared, or PTR4 is Null.
To determine. If the resource acquisition priority of the called write-related process is high, or if PTR4 is Null, the semaphore PTR4 is updated to point to the PCB 6 of this process (S302), otherwise the value of PTR4 is not updated. Finally, the called write processes are inserted into the resource waiting process list in the order of resource acquisition priority (descending order) (S206), put into the sleep state and execution is blocked until the resources are released (S1904). The write-related process whose blockade has been released due to the process that has locked the resource executing the V instruction part restarts processing from step S303.

Next, referring to FIG. 4, the read system V instruction unit 4
The processing flow of 0 will be described. First, it is determined whether or not the reading process that called this process is the only reading process that occupies the resource (S401).
If it is not the only reading process (No), the value of the variable readcounter that counts the number of reading processes currently accessing the resource is decremented by 1 (S403).
Only ends the process. On the other hand, if the calling read process is the only read process that is accessing the resource, the same processes S2001 to S2004 as the conventional V command unit 200 are performed to release the resource.
First, the value of the semaphore is incremented by 1 (S2001), and as a result, the value of the semaphore is not 0 or less (S2002, N
o) Since there is no process waiting for resource acquisition, S403 is executed and the process ends. If the value of the semaphore as a result of S2001 is a value of 0 or less (S2002, Ye
s), there are processes waiting for resource acquisition. Therefore, the semaphore PTR4 is rewritten to point to the write-related process having the next highest resource acquisition priority. If there is no next write-related process, Null is set (S40).
2). Next, from the head of the waiting process list, set PCB to 1
One is taken out (S2003), and execution of the process of the PCB is restarted (S2004). Then readco
The value of unter is decremented by -1 (S403), and the process ends.

Next, referring to FIG. 5, the write system V command section 5
The processing flow of 0 will be described. S2001, S200
2 is the same as the conventional V command section. If the determination in S2002 is No, it means that there is no process waiting for the resource, and the process is terminated as it is. On the other hand, S2
If the determination of 002 is Yes, it means that there is a process waiting for the resource acquisition, and therefore, the process of restarting the execution of the process waiting for the resource is performed. The process for restarting the execution of the waiting process is the PT of the semaphore S.
It is determined whether the value of R is Null (S203), and Null
In the case of (S203, Yes), since there is no write-related process waiting for the resource acquisition, the process proceeds to S502. In S502, all the waiting processes are reading processes, so all the processes are removed from the list. Next, in step S504, execution of all the processes removed from the list is restarted, and the processing ends. S203
If the determination is No, first, it is determined whether the resource request lock mode of the first process in the resource waiting process list is the write mode (S501), and if it is the write mode (Yes), the PTR4 in the semaphore S After updating the PCB6 of the writing process with the next highest resource acquisition priority among the waiting processes (Null when there is no next writing process) (S402), the first PCB6 in the waiting process list is updated. The process is deleted from the list (S2003), the process corresponding to the PCB is changed from the sleep state to the executable state (S504), and the process ends. If the result of the determination in S501 is that the resource request lock mode 8 of the process at the head of the resource waiting process list is the read mode (No), all reads from the beginning of the resource waiting process list to immediately before the write-related process pointed to by PTR4. The system process is removed from the waiting process list (S503), each process is changed from the sleep state to the executable state (S504), and the process ends.

Next, the processing flow of FIGS. 2 to 5 will be specifically described by taking as an example the case where the processes A to G shown in FIG. 6 access one file. Here, pr in FIG.
i means the resource acquisition priority of each process. (1) Process A issues a read request to a file. However, it is assumed that no process has accessed before this. The read P command section in FIG. 2 sets the resource lock mode 8 of this process to the read mode (S
201). Next, set the value of value of semaphore S to -1
To 0 (S1901). Semaphore S value
Whether the value of is 0 or less (S1902) At this time value
Since the value of is 0, the result is No, and the reading process that called this process can acquire the resource. Then, next in S207, the readcount of the semaphore S
The value of er is incremented by 1 to be +1. In S208, the lock mode of the semaphore S is set to the read mode, and the process ends.

(2) Process B requests the file for reading. In FIG. 2, the value of the value of the semaphore S becomes -1 (S1901). Next, since the value of the semaphore S becomes 0 or less in S1902, the process proceeds to S202. In S202, it is checked whether the lock mode of the semaphore S is the write mode. In this case, since it is the read mode, the determination is No, and the process proceeds to S203. In S203, in order to check whether or not there is a process pointed to by the PTR, it is determined whether the PTR is Null, and the result is Yes and the process proceeds to S205. Va of the semaphore S in S205
Add 1 to the value of lue. Next, in S207, the value of readcounter of the semaphore S is incremented by one. Set the lock mode of the semaphore S to the read mode (S20
8) The process ends. At this point, process A and process B are reading from the file, so readco
The value of unter is 2, and the value of value of the semaphore S is 0. If the reading processes are accessing at the same time, -1 is performed in S1901 of FIG.
Since +1 is performed in 205, the value of the semaphore S does not change no matter how many read-related processes increase.

(3) The C process requests writing to the file. Since it is a write request, it follows the flow of processing of the write-system P command section in FIG. In S301, the resource lock mode of this process is set to the write mode. S1
In 901, the value of the value of the semaphore S is subtracted by -1 to obtain -1. The value of the semaphore S is 0 in S1902.
It becomes the following because it becomes the following, PTR in S203
Is Null. Where PTR is Null
Therefore, the result is Yes, and then the process of S302 is performed.
In S302, the PTR is updated to point to this process. In S206, this process is added to the waiting process list of the semaphore S. In step S1904, this process is put to sleep. The waiting process list at this time is shown in FIG. In FIG. 7, the waiting process list pointer 181 points to the PCB 6 of the C process, and the value 182 of the value in the semaphore management table 2 becomes -1, and since the processes A and B are reading at this time, the value of readcounter is 2. Becomes Since the C process is a write process, the PTR4 indicates the PCB 6 of the C process. Next, the lock mode is read. Also, the PCB 6 of the C process has the resource acquisition priority 7 of 4
And the resource lock mode 8 is write.

(4) The D process requests the file to be read. Since it is reading, the processing of the reading system P command section in FIG. 2 is followed. The value of semaphore S becomes -2, and S2
02, S203, and S204. In S204, it is checked whether the resource acquisition priority of this process is higher than the resource acquisition priority of the process pointed to by the PTR of the semaphore S. From FIG. 7, the resource acquisition priority of the process pointed to by the PTR of the semaphore S is 4, and the resource acquisition priority of the D process is 2, so the result is No, and then S20.
Go to 6 processing. In S206, this process is added to the waiting process list of the semaphore S in the resource acquisition priority order, and this process is put to sleep (S1904). FIG. 8 shows the semaphore management table and process control block at this time. In FIG. 8, the value value of the semaphore is -2 in the semaphore management table, and the PCB of the D process is pointed after the C process of FIG. (5) Process E makes a write request. Since this is a write request, the processing of the write-related P command section in FIG. 3 is followed. Since the value of the semaphore S is -3, the process goes to S203. S
Since PRT is not Null in 203, S20
In step 4, it is checked whether the resource acquisition priority of this process is higher than the resource acquisition priority of the process pointed to by the PTR of the semaphore S. E process resource acquisition priority is 1
Since the resource acquisition priority of the C process indicated by the PTR of the semaphore S is 4, the result is No and the process proceeds to S206. After S206, this process is added to the waiting process list of the semaphore S and put into a sleep state. FIG. 9 shows the semaphore management table and the PCB at this time. FIG. 9 is a diagram in which the PCB of the E process is added to FIG. The value of value in the semaphore management table at this time is -3.

(6) Process F issues a read request.
The resource acquisition priority of the F process is 5. The processing of the read system P command section in FIG. 2 is followed. The value of the semaphore S becomes -4, and the processing passes to S202, S203, and S204. S
In 204, since the resource acquisition priority of the process pointed to by the PTR is 4 and the resource acquisition priority of the F process is 5, the answer is Yes, and the file can be accessed S2.
Go to 05. In S205, the value of semaphore S is incremented by +1
Then it becomes -3. Next, in S207, the semaphore S
The value of readcounter of is incremented by 1 and set to 3. Set the lock mode of the semaphore S to read mode (S
208) Finish. At this time, since the resource acquisition priority of the F process is higher than the resource acquisition priority of the C process indicated by the PTR of the semaphore S, the process can be performed without waiting for reading from the file. The F process will not be added to the waiting process list because the reading will start immediately. (7) The G process requests reading. The resource acquisition priority of the G process is 3. The processing of the read system P command section in FIG. 2 is followed. The value of semaphore S becomes -4, and S20
The process passes through 2, 203, and 204. In S204,
Since the resource acquisition priority of the process pointed to by the PTR of the semaphore S is 4, and the resource acquisition priority of this process is 3, the determination is No and the process proceeds to S206. In S206, this process is added to the waiting process list of the semaphore S in the order of resource acquisition priority. This process is put to sleep (S1904), and the process ends. FIG. 10 shows the semaphore management table and PCB at this point. 10 is different from FIG. 9 in that the G process newly added to the waiting process list has a resource acquisition priority of 3, so that it is added between the C process and the D process. The value of value in the semaphore management table is -4, and readcou
The value of nter is +3.

(8) Next, the F process finishes reading. Since this is the end of reading, the processing of the read system V instruction section in FIG. 4 is followed. In S401, re of the semaphore S
Whether or not the value of adcounter is 1 is checked. In this case, since it is +3, the determination is No and the process proceeds to S403. Since it is not the last reading process, the value of readcounter of the semaphore S is set to 2 in S403, and the process is terminated. (9) Process A finishes reading. The processing of the read system V instruction section in FIG. 4 is followed. As in (8), when checking whether it is the last read-related process, rea
Since the value of dcounter is 2, S401 is No and the process of S403 is performed. In step S403, the value of the read counter of the semaphore S is set to 1, and the process ends.

(10) Completion of reading of process B and start of writing of process C. Completion of the reading of the B process follows the process of the reading V instruction section in FIG. In this case, re
Since the value of adcounter is 1, the result in S401 is Yes, and the process of S2001 is performed. S2001
+1 if the value of the value of the semaphore S is +1
Becomes Since the value of the semaphore S is 0 or less in S2002, the determination result is Yes, and the process of S402 is performed. When the PTR value is updated in S402, the PTR points to the E process. In step S2003, the process is removed from the head of the waiting process list of the semaphore S. In this case, the C process PCB is removed from the beginning. And S2004
Change the process removed from the list from the dormant state to the runnable state. In S403, the value of the readcounter of the semaphore S is decremented by 1 to 0, and the process ends. The number of reading processes is 0
It was cleared. Next, the process changed to the executable state in S2004 is the C process. Since the C process is a write request, it starts from the sleep process S1904 of the write-related P command section in FIG. In S303, the lock mode of the semaphore S is set to the write mode, and the process ends. Figure 1 shows the semaphore management table and PCB at this time.
It is shown in FIG. In FIG. 11, the C process of FIG. 10 is omitted, and the PTR pointer points to the E process. The value of value in the semaphore management table is -3, and re
The value of adcounter is 0, and the lock mode is write.

(11) Writing of C process is completed and reading of G process and D process is started. Since the C process is a write request, the process of the write-related V command section in FIG. 5 is followed for termination. S2001: Semaphore S
Has a value of -2. Next, in S2002, the semaphore S
Since the value of is 0 or less, the determination result is Yes, and the process of S203 is performed. Since the PTR is not Null in S203, the determination is No, and the process proceeds to S501. In S501, in order to check whether or not the head of the waiting process list is a write system, it is checked whether the PTR points to the head process of the waiting process list. In this case, since No is obtained from FIG. 11, the process of S503 is performed. In step S503, PT from the head of the waiting process list of the semaphore S
Remove all processes up to immediately before the process pointed to by R. Next, in step S504, all the processes removed from the list, in this case the G process and the D process, are changed from the sleep state to the executable state. With the above, the C process ends, and then the G process and the D process start. Since both the G process and the D process are read systems, they follow the processing of the read system P command section in FIG. S in FIG.
The process of 207 starts. First, the G process shifts from the sleep state to the executable state, and the value of readcounter of the semaphore S is incremented by 1 and set to 1 in S207.
In S208, the lock mode of the semaphore S is set to the read mode, and the process ends. Next, the D process is S207.
Start more. In S207 readcount
Let the value of r be +2. Next, in S208, the semaphore S
Set the lock mode of to read mode and exit.
As a result, the G process and the D process start reading from the file. Semaphore management table and P at this point
CB is shown in FIG.

As described above, since the resource waiting process is controlled by the resource acquisition priority, it is possible to automatically avoid the resource starvation state of the writing process in the conventional shared exclusive control.

Example 2. In the second embodiment, the structure of the semaphore of the first embodiment and the P instruction part (20, 30) / V instruction part (4
(0, 50), the attribute value of the process normally managed in the PCB 6 is used as the resource acquisition priority 7 of the process in the PCB 6.

An outline of the P command section according to this embodiment will be described. 13 shows a flow chart of the read system P command section 60, and FIG. 14 shows a flow chart of the write system P command section 70. First, the unique process attribute value managed in the PCB 6 is set to the resource acquisition priority 7 in the PCB (S601). After that, if the lock mode specified by the argument is the read system (R), the read system P command unit 20 of the first embodiment is used, and if the lock mode is the write system (W), the write system P command unit 30 of the first embodiment is used. To do. On the other hand, V in the present embodiment
The command part is the same as the V command part (40, 50) of the first embodiment.

As described above, the semaphore of this embodiment automatically avoids the occurrence of the resource starvation state of the write-related process in the conventional shared exclusive control by using the attribute value of the process as the resource acquisition priority. You can

Example 3. This example is the same as P described in Example 2.
This is the case where the scheduling priority of the process is used as the attribute value of the process used as the resource acquisition priority in step S601 of the instruction part (60, 70).

The resource management apparatus of the present embodiment is effective in a real-time system using fixed priority scheduling because resources are allocated in the order of higher process scheduling priority.

Example 4. This example is the same as P described in Example 2.
In step S601 of the instruction part (60, 70), the number of resources currently locked by the process is used as the attribute value of the process used as the resource acquisition priority. FIG.
Is an example of how to count the number of resources that are locked. In FIG. 15, it is assumed that three types of semaphores of A, B, and C are used in a certain process. At this time, as can be seen from FIG. 15, when P (A), when the semaphore A is acquired, the number of resources in lock is 1, then at the stage when P (B) and semaphore B are acquired, The number of resources locked is 2,
Next, when P (C) and semaphore C are acquired, the number of locked resources becomes 3, and V (C), V (B), V
As the semaphore is released in (A), the number of locked resources becomes 2, 1, 0. The number of resources locked by a process is counted in this way.

In the resource management system of this embodiment, the resources are allocated to the processes in the descending order of the number of resources locked by the process, so that the throughput of the entire system is improved.

Example 5. In the present embodiment, a process operates on an operating system that employs a paging-type virtual storage system that uses an auxiliary storage device such as a disk device to make it appear that the main storage capacity is larger than the actual capacity of the main memory device. That is the case. In step S601 of the P command (60, 70) described in the second embodiment, as the attribute value of the process used as the resource acquisition priority, the operation image of the process is not the auxiliary storage device but the occupancy amount of the main memory, for example, on the main memory. A value indicating how many pages are held, that is, the number of pages in the main memory of the process execution image is used.

In the case of the present embodiment, a process having a large number of pages in the main memory of the process execution image requires less copying of the process execution image from the auxiliary storage device to the main memory device during its operation. It can be expected that the time required will be short. Therefore, by allocating resources to processes in descending order of the number of pages in the main memory of the process execution image, it is possible to allocate resources preferentially to processes that are expected to require a short processing time, and the overall system throughput improves.

Example 6. This example is the same as P described in Example 2.
In step S601 of the instruction part (60, 70), CP is used as the attribute value of the process used as the resource acquisition priority.
Use U usage time.

In the case of this embodiment, resources are allocated to processes in the order of increasing CPU usage time of processes, so resources should be allocated preferentially to processes that are likely to serve important applications or other applications. You can

Example 7. In this embodiment, in order to use it as a guideline for deciding which process should be prioritized when the system is overloaded, for example, in addition to the CPU schedule priority, the process processing importance is set as an attribute for each process. The process is running on the operating system that is running. In step S601 of the P command (60, 70) described in the second embodiment, the process processing importance of the process is used as the attribute value of the process used as the resource acquisition priority.

In the case of this embodiment, resources are promptly allocated to the process having a higher processing importance, and the process having a higher processing importance can be smoothly processed.
Facilitates the achievement of the purpose of setting the process attribute of processing importance.

Example 8. In this embodiment, the structure of the semaphore of the first embodiment and the P instruction section (20, 30) / V instruction section (4
0, 50), and the value dynamically set by the user is used as the value set for the resource acquisition priority 7 in the PCB 6.

An outline of the P command section according to this embodiment will be described. FIG. 16 is a flowchart of the read P command section 80, and FIG. 17 is a flowchart of the write P command section 90. The P command section uses semaphores (S), lock modes (RorW), and resource acquisition priority values (Pr) as arguments.
i) is specified. First, the value specified by the user (argument Pr
i) is set to the resource acquisition priority 7 of the process in the PCB 6 (S801), and thereafter, if the argument lock mode is the read mode (R), the read system P command unit 2 of the first embodiment
0 processing, argument lock mode is write mode (W)
If so, the processing of the write system P command unit 30 of the first embodiment is performed. On the other hand, the V command part in this embodiment is the same as the V command part (40, 50) in the first embodiment.

In the case of the present embodiment, the user can freely set the resource acquisition priority value for each process for each resource, and finer resource management can be performed.

Example 9. In this embodiment, the structure of the semaphore of the first embodiment and the P instruction section (20, 30) / V instruction section (4
0, 50) is basically used, and the value specified in advance (statically) by the user is used as the value set for the resource acquisition priority 7 in the PCB 6. In the present embodiment, the means of the first embodiment and the means for setting the resource acquisition priority value in advance in the table for managing the resource acquisition priority 7 value for each process for each resource will be provided.

An outline of the P command section according to this embodiment will be described. FIG. 18 is a flowchart of the read system P command unit 100, and FIG. 19 is a flowchart of the write system P command unit 110. The resource acquisition priority management table 120 is registered by the resource acquisition priority registration means 1002. From the resource acquisition priority management table 120, the resource acquisition priority for the semaphore S (resource) of the process Pi that called this P command unit is acquired, and the value is acquired by the PC of the process.
It is set in the resource acquisition priority storage area 7 of B6 (S100).
1, S1101). At this time, if the lock mode specified by the argument of the P command part is the read mode (R), the management table of the read system resource acquisition priority is set, and if the write mode (W), the write system resource acquisition priority management table is set. Refer to. FIG. 20 shows the structure of a table that manages the value of the resource acquisition priority 7 for each resource for each process.
Pi indicates a process, and Sj indicates a semaphore (resource). For example, the semaphore S of the process P2 in FIG.
The resource acquisition priority for 1 is 3. Step S10
01 or after step S1101, if the argument lock mode is the read mode (R), the read system P command section 20 of the first embodiment is used. If the argument lock mode is the write mode (W), the write system P of the first embodiment is used. The instruction unit 30 is executed. On the other hand, the V instruction part in this embodiment is the same as that in the first embodiment.
V command section (40 and 50).

In the case of this embodiment, the value of the resource acquisition priority can be freely set for each resource for each process, and finer resource management can be performed for each resource.

Example 10. In the present embodiment, the predicted value of the lock time for the semaphore Sj of the process Pi is used as the value registered in the resource acquisition priority management table 120 in the ninth embodiment. Lock time is from P (S) to V
It is the time between (S), that is, the time from the acquisition of the semaphore S to the release.

In the case of this embodiment, since the resources are allocated in the ascending order of the process semaphore lock time, the throughput of the entire system can be increased.

Example 11. The present embodiment is based on the structure of the semaphore of the first embodiment and the processing of the P command part (20, 30) / V command part (40, 50), and an arbitrary number of scales are used as the resource acquisition priority in the above embodiment. 2 in the P command section (20, 30) in the step S204 and the step S206 of FIG. 3, the resource acquisition priority is compared by a combination of these scales.

For example, as a combination of scales, a combination of two scales, that is, a value explicitly specified at the time of resource acquisition request and a process schedule priority is adopted. Assume that a comparison method is adopted in which the resource acquisition priority is higher when the value is larger, and when the value explicitly specified is the same, the resource acquisition priority is higher when the process schedule priority is higher. First, when a resource acquisition request is made, the process with the larger explicitly specified value is given priority, and if the explicitly specified value is the same, the process with the higher process schedule priority is given priority. Thus, it is possible to achieve resource allocation, and it is possible to realize resource allocation that utilizes the process attribute of process schedule priority while making use of the explicitly specified value.

In this embodiment, two values, that is, a value explicitly specified at the time of resource acquisition request and a schedule priority of a process, which is a kind of process attribute, are used. Compared mainly, the priority of resource acquisition is judged to be high or low. However, this may mainly compare the schedule priorities of the processes, may adopt the attributes of the processes together as the two measures, and further, as one of the measures, the acquisition priority for each resource in advance for each process. The registered value may be adopted. Further, the number of scales to be used is not limited to two and may be three or more, and an arbitrary scale combination and an arbitrary comparison method for the scale combination can be adopted.

In the case of the present embodiment, it is possible to make a finer and more flexible judgment than in the case where a single scale is used as the resource acquisition priority, and as a characteristic of the judgment of which process is to be given priority to acquire the resource. , It has the effect that the resource management mechanism can set more suitable characteristics required for system construction.

Example 12 This embodiment is based on the structure of the semaphore of the first embodiment and the processing of the P command section (20, 30) / V command section (40, 50), and is based on the above-mentioned first to first embodiments.
In addition to providing all means up to 1, it is characterized by further having means for statically selecting one of the methods of the embodiment in advance as a resource acquisition priority for each resource. .

An outline of the P command section according to this embodiment will be described. FIG. 21 is a flowchart of the read P command section 150, and FIG. 22 is a flowchart of the write P command section 160. First, the resource acquisition priority setting method for the semaphore S is identified from the resource acquisition priority setting method management table 170 (S1501). FIG. 23 is a table 1 for managing the resource acquisition priority setting method for each resource.
70 shows the structure of 70. Sj indicates a resource. For example, in FIG.
The setting method of the resource acquisition priority for the semaphore S2 in is the setting method of the third embodiment. The processing from step S1501 onward is in accordance with the resource acquisition priority setting method, and if the argument lock mode is the read mode (R), any one of the third to eighth embodiments, the ninth embodiment, the tenth embodiment, and the eleventh embodiment. Read system P command section (20, 60, 80, 10
0) when the argument lock mode is the write mode (W), the write system P command section (30, 7) of any of the third to eighth embodiments, the ninth and tenth embodiments, and the eleventh embodiment.
0, 90, 110). On the other hand, V in the present embodiment
The command part is the same as the V command part (40, 50) of the first embodiment.

In the case of the present embodiment, since the resource acquisition priority setting method suitable for the characteristics of each resource can be selected, more detailed resource management can be performed.

Example 13 How to determine the priority of resource acquisition
Other than those described in the above embodiment, any one can be used as long as the order can be determined. For example, the resource acquisition priority may be given from the earliest to the lowest in the process resource acquisition request. When resource acquisition requests are issued in the order of process A (reading), process B (reading), process C (writing), process D (reading), process E (reading), process F (writing), the order is highest from process A. Give a resource acquisition priority, for example 10 to 5,
Add to resource waiting process list.

At this time, in order to avoid the resource allocation starvation state of the writing process, the resource acquisition priority of the writing process may be set to a certain value or more. For example, if the resource acquisition priority of the writing process is always 7 or more, the resource acquisition priority of the above process A is 10, the process B is 9, the process C is 8,
The process D is 7, the process E is 6, and the process F is 7. A resource waiting process list in this case is shown in FIG. Since the process F is a writing process, the resource acquisition priority is 7, and it enters between the processes D and E as shown in FIG.

As described above, the process resource acquisition priority may be determined according to the purpose as long as the order can be determined.

[0087]

As described above, according to the present invention,
Efficient resource management, which is the original purpose of shared exclusive control, can be realized.

Further, according to the present invention, it is possible to improve the development efficiency of the application design and the normal operation of the system by automatically avoiding the write-related process from starving into resource allocation according to the resource acquisition priority. It is possible to guarantee and at the same time improve the throughput of the entire system, and to perform flexible resource management.

Further, according to the present invention, by using the attribute value of the process as the resource acquisition priority, it is possible to automatically avoid the resource starvation state of the writing process in the conventional shared exclusive control.

Further, according to the present invention, resources are allocated in the descending order of process scheduling priority, which is effective in a real-time system using fixed priority scheduling.

Further, according to the present invention, since the resources are allocated to the processes in the descending order of the number of resources locked by the process, the throughput of the entire system is improved.

Further, according to the present invention, by allocating resources to a process in the order in which the main memory occupation amount of the process execution image, for example, the number of pages in the main memory is large, a process expected to have a short processing time can be obtained. It is possible to allocate resources preferentially, and the throughput of the entire system is improved.

Further, according to the present invention, resources are allocated to processes in the descending order of process usage time, so resources are preferentially allocated to important processes or processes that are likely to be serving other applications. You can

Further, according to the present invention, resources are promptly allocated to a process having a higher processing importance, so that a process having a higher importance can be smoothly processed. Promote the achievement of the purpose of setting attributes.

Further, according to the present invention, the user can freely set the resource acquisition priority value for each resource for each process, and more detailed resource management can be performed.

Further, according to the present invention, the value of the resource acquisition priority can be freely set for each process for each resource, and finer resource management can be performed for each resource.

Further, according to the present invention, resources are allocated in the ascending order of semaphore lock time of a process, so that the throughput of the entire system can be increased.

Further, according to the present invention, it is possible to make a finer and more flexible judgment as compared with the case where a single measure is used as the resource acquisition priority, and it is possible to judge which process is given higher priority to acquire the resource. As a characteristic, it has an effect that a more suitable characteristic required for system construction can be set for the resource management mechanism.

Further, according to the present invention, a resource acquisition priority setting method suitable for the characteristics of each resource can be selected.
Finer resource management can be performed.

[Brief description of drawings]

FIG. 1 is an explanatory diagram of a semaphore structure according to an embodiment of the present invention.

FIG. 2 is a flowchart diagram of a read system P command section using a semaphore according to the first embodiment.

FIG. 3 is a flowchart of a write system P command section using a semaphore according to the first embodiment.

FIG. 4 is a flowchart diagram of a read system V instruction unit using a semaphore according to the first embodiment.

FIG. 5 is a flowchart diagram of a write system V instruction unit using the semaphore according to the first embodiment.

FIG. 6 is a diagram showing a timing of accessing a file by a reading process and a writing process.

FIG. 7 is a diagram showing a semaphore management table and a PCB at the time of ending (3) in FIG.

FIG. 8 is a diagram showing a semaphore management table and a PCB at the end of (4) in FIG.

9 is a diagram showing a semaphore management table and a PCB at the end of (5) in FIG.

10 is a diagram showing a semaphore management table and a PCB at the end of (7) in FIG.

11 is a diagram showing a semaphore management table and a PCB at the end of (10) in FIG.

FIG. 12 is a diagram showing a semaphore management table and a PCB at the end of (11) in FIG.

FIG. 13 is a flowchart diagram of a read P command section using a semaphore according to the second embodiment.

FIG. 14 is a flowchart diagram of a write system P command section using a semaphore according to the second embodiment.

FIG. 15 is a diagram showing an example of how to count the number of locked resources.

FIG. 16 is a flowchart diagram of a read system P command section using a semaphore according to the eighth embodiment.

FIG. 17 is a flowchart diagram of a write system P command section using a semaphore according to the eighth embodiment.

FIG. 18 is a flowchart diagram of a read P command section using a semaphore according to the ninth embodiment.

FIG. 19 is a flowchart diagram of a write system P command section using a semaphore according to the ninth embodiment.

FIG. 20 is an explanatory diagram of a resource acquisition priority management table according to the ninth embodiment.

FIG. 21 is a flowchart diagram of a read system P command section using a semaphore according to the twelfth embodiment.

FIG. 22 is a flowchart diagram of a write system P command section using a semaphore according to the twelfth embodiment.

FIG. 23 is an explanatory diagram of a management table of a resource acquisition priority setting method according to the twelfth embodiment.

FIG. 24 is a diagram showing an example of a waiting process list according to the thirteenth embodiment.

FIG. 25 is an explanatory diagram of a structure of a conventional semaphore.

FIG. 26 is a flowchart of the P command section of the conventional semaphore.

FIG. 27 is a flowchart of the V instruction section of the conventional semaphore.

[Explanation of symbols]

1 memory, 2 semaphore management table, 3 read
counter, 4PTR, 5 lock mode, 6 process control block (PCB), 7 resource acquisition priority,
8 resource lock mode, 10 exclusive control unit, 18 conventional exclusive control unit, 20 read P command unit, 30 write P command unit, 40 read V command unit, 50
Write system V command part, 180 Conventional semaphore management table, 181 Wait process list pointer, 182
value, 183 Conventional process control block (P
CB), 184 next pointer, 190 conventional P
Command part, 200 Conventional V command part.

Claims (13)

[Claims] 1. A resource management device for shared resources having the following elements: (a) a read instruction unit for executing exclusive acquisition of a shared resource for a read process and an exclusive write process. An exclusive control unit having a write-related instruction unit that executes acquisition of shared resources, and (b) the read-related instruction unit of the exclusive control unit is executed by the read-related process and Control means for executing the write command section of the exclusive control section. 2. The control means allocates a resource acquisition priority to a read process and a write process, and acquires the resource by the exclusive control unit for the read process and the write process based on the resource acquisition priority. The resource management device according to claim 1, wherein the order is determined. 3. The resource management device according to claim 2, wherein a process-specific attribute value is used as the resource acquisition priority. 4. The resource management apparatus according to claim 3, wherein the scheduling priority of the process is used as the attribute value unique to the process. 5. The resource management device according to claim 3, wherein the number of occupied resources of the process is used as the attribute value unique to the process. 6. The resource management apparatus according to claim 3, wherein the main memory occupation capacity of the process execution image existing on the main memory is used as a process-specific attribute value. 7. The resource management apparatus according to claim 3, wherein the CPU usage time of the process is used as the attribute value unique to the process. 8. The resource management device according to claim 3, wherein the processing importance of the process is used as a process-specific attribute value. 9. The resource management device according to claim 2, wherein the value of the resource acquisition priority can be explicitly designated at the time of a resource acquisition request. 10. The resource management apparatus according to claim 2, further comprising means for registering the resource acquisition priority in advance for each resource for each process. 11. The resource occupation time of a process is used as the value of the resource acquisition priority.
The described resource management device. 12. The resource management device according to claim 2, wherein the value of the resource acquisition priority is determined by a combination of arbitrary scales. 13. The resource management apparatus according to claim 2, further comprising a plurality of resource acquisition priority setting methods, and means for selecting a resource acquisition priority setting method for each resource.