JP6590403B2 - Communication device and backup control method - Google Patents

Description

  The present invention relates to a file backup technique, and more particularly to a backup control method in a communication device such as a portable terminal.

  A communication device such as a portable terminal that is frequently used by a user needs to perform highly reliable backup within a limited resource, and several techniques have been proposed for that purpose (see, for example, Patent Document 1). .

  An information processing apparatus that performs parallel processing also requires resource management in preparation for a memory shortage when a plurality of processes are executed simultaneously. For example, in the data processing apparatus disclosed in Patent Document 2, when the memory allocated to two processors exceeds a threshold value, memory management is performed such that one processor performs fallback and allocates the surplus memory to the other processor. By doing so, the process stop due to memory shortage is avoided.

JP 2005-189969 A JP 2011-126210 A

  However, in a communication device with a limited amount of mounted memory, if backup processing is executed while other processes such as call control processing are being executed simultaneously, the memory is used for backup, resulting in insufficient memory. Is likely to occur. If a memory shortage occurs, even if memory management is performed, there is a possibility that the call control process is affected and a call loss may occur, and the call may be disconnected. Such a problem occurs especially when the size of the file to be backed up is large (a large amount of memory is used in the backup process) in a communication terminal with a small installed memory capacity. It becomes remarkable when using it.

  Such a memory shortage problem caused by the backup process can be solved by limiting the amount of memory allocated to the backup process by the operating system (OS). For example, in Linux (registered trademark, the same applies hereinafter), cgroup (a mechanism for allocating resources such as CPU time, memory, and network bandwidth among user-defined process groups) for a process group that performs backup processing By setting an upper limit on the memory usage, even if the backup process is executed, the memory exceeding the setting can be prevented from being used. Thereby, it is possible to avoid the influence on other processing such as call control processing in the communication terminal.

  However, in the memory usage limitation by such OS, when the memory usage reaches the upper limit value, the process is forcibly terminated when a predetermined process forcible termination function (for example, OOM Killer in Linux) is set, If the process forced termination function is not set, the process will stop, so there is a problem that backup processing cannot be terminated normally.

  Furthermore, merely suspending the backup process due to the memory usage limit merely stops the increase in the memory usage for backup, and the memory usage used at that time remains maintained. This makes it impossible to eliminate the influence on the call control processing and the like due to the occurrence of memory shortage in the communication terminal.

  SUMMARY OF THE INVENTION An object of the present invention is to provide a communication device and a backup control method thereof that can normally terminate backup processing and eliminate the influence on other processing (call control processing or the like).

The communication device according to the present invention is a communication device having a file backup function, and whether or not the amount of memory used for backup processing exceeds a predetermined value smaller than a memory upper limit value assigned to the backup processing. Monitoring means for monitoring the backup processing, and control means for temporarily stopping execution of the backup processing and releasing a memory area related to the backup processing in the cache when the memory usage of the backup processing exceeds the predetermined value It is characterized by having.
A communication device according to the present invention is a communication device having a file backup function, and a backup execution means for executing backup processing, and a memory usage amount used for backup processing is a memory upper limit value assigned to the backup processing. A temporary stop instruction means for temporarily stopping the backup processing when a predetermined value smaller than the predetermined value, and according to the temporary stop instruction, the backup processing by the backup execution means is temporarily stopped and related to the backup processing in the cache And a control means for releasing the memory area.
A backup control method according to the present invention is a backup control method for a communication device having a file backup function, wherein the monitoring means uses a memory usage amount used for backup processing from a memory upper limit value assigned to the backup processing. And the control means suspends execution of the backup process when the memory usage of the backup process exceeds the predetermined value, and the backup process in the cache The memory area related to the is released.
The program according to the present invention is a program for causing a computer to function as a communication device having a file backup function, wherein a memory usage amount used for backup processing is smaller than a memory upper limit value assigned to the backup processing. A first function for monitoring whether or not a value has been exceeded, and a control means, when the memory usage of the backup process exceeds the predetermined value, temporarily stops the execution of the backup process, and the backup in the cache A second function of releasing a memory area related to processing is realized in the computer.

  As described above, according to the present invention, the backup process can be normally terminated and the influence on other processes can be eliminated.

FIG. 1 is a schematic system configuration diagram of a communication apparatus according to an embodiment of the present invention. FIG. 2 is a schematic diagram showing main processes during the process execution of the backup control method according to the present embodiment. FIG. 3 is a schematic diagram showing a mechanism for suppressing the memory usage of the backup execution process by the backup control method according to the present embodiment. FIG. 4 is a flowchart showing the backup main process in FIG. FIG. 5 is a flowchart showing the freeze instruction process in FIG. FIG. 6 is a flowchart showing the cache release instruction process in FIG. FIG. 7 is a flowchart showing the backup execution process in FIG. 8A is a diagram showing an example of a backup target file list, FIG. 8B is a diagram showing an example of a memory usage current location file, and FIG. 8C is a diagram showing an example of a freeze state file. FIG. 9 is a graph showing the time change of the memory usage when the backup control method according to the present embodiment is applied.

<Outline of Embodiment>
According to the embodiment of the present invention, when the memory usage of the backup process exceeds a predetermined value, the memory area related to the backup process in the cache is released in addition to the suspension of the backup process. Thereby, the occurrence of memory shortage can be prevented in advance, and the influence of backup processing on call processing control or the like can be eliminated.

  Hereinafter, an embodiment of the present invention will be described in detail using Linux as an example. However, the present invention is not limited to Linux, and can be applied to other OSs as long as they have equivalent functions.

1. System Configuration As illustrated in FIG. 1, the OS kernel 11 of the communication device 10 such as a mobile terminal links the hardware 12 and the application, and a process group 13 including a plurality of processes P1, P2,. Assume that processes Px... Are operating. According to the present embodiment, the process group 13 is a process group that executes backup processing, and the other processes Px and the like are processes or process groups that execute call control processing and the like. The OS kernel 11 executes execution management of a plurality of processes, resource management for assigning resources to backup processing, call control processing, and the like.

According to this embodiment, the following functions are implemented in the process group 13 that performs backup processing.
1) Process group 13 suspend function (eg, provided by cgroup's freezer subsystem in Linux);
2) The current total memory usage confirmation function of the process group 13 (for example, provided by the cgroup memory subsystem in Linux);
3) A function of temporarily stopping the process group 13 when the current total memory usage of the process group 13 exceeds the reference value TH1;
4) A function for canceling the temporary stop of the process group 13 when the current total memory usage of the process group 13 falls below the reference value TH1;
5) Cache release function (for example, the function provided by the function posix_fadvise () in Linux); and 6) The order of the compression processing of the files to be subjected to compression processing to specify the target file for cache release, the compression processing A function to create / update a list of files to be backed up so that the completion status can be seen.

  The OS kernel 11 and the plurality of processes can be realized by executing an OS program and an application program stored in a memory in the hardware 12. Hereinafter, backup control according to the present embodiment will be described in detail with reference to the drawings.

2. Operation 2.1) Execution of Backup Process As shown in FIG. 2, when the backup process is executed, the backup main process 101 starts the backup target file list 102, the freeze instruction process 103, the cache release instruction process 104, and the backup execution process. 105 are respectively generated. The backup execution process 105 is registered in the cgroup memory subsystem (/ cgroup / memory / test) and freezer subsystem (/ cgroup / freezer / test).

  The backup main process 101 waits for the end of the backup execution process 105 after generating each process. When the backup execution process 105 ends, a process end notification is issued to the freeze instruction process 103 and the cache release instruction process 104.

  The backup target file list 102 is a list in which files to be backed up are listed in the order of backup processing. When the backup target is specified in units of directories instead of in units of files, for example, if the command is a file compression command (tar command), the file name in that directory is backed up by obtaining the directory entry with the function readdir () Can be acquired in the order of processing. In this way, files to be backed up can be described in the backup target file list in the order of backup processing.

2.2) Backup Control FIG. 3 shows a mechanism for reducing the memory usage of the backup execution process 105 by operating in cooperation with the cache release instruction process 104 and the freeze instruction process 103 while the backup execution process 105 is being executed. Show.

  In FIG. 3, the backup execution process 105 designates an option (-v for tar) to display a compressed file name after each file compression is finished in a file compression command such as tar. Each time compression is completed, the compressed file name is output to the compressed file list 110 (operation S201).

  The cache release instruction process 104 monitors the file name newly described in the compressed file list 110 (operation S202), and updates the backup target file list 102 if there is a new file name (operation S203). ). Further, the cache release instruction process 104 determines a file name for designating cache release based on the backup target file list 102, and uses the function posix_fadvise () for the kernel 11 to use the cache used by the designated file. Is issued (operation S204).

  The freeze instruction process 103 monitors the memory usage current value file 111, and if the memory usage current value exceeds the reference value TH1, issues a freeze (pause) execution instruction to the freeze state file 112 (FROZEN Write). If the current memory usage value falls below the reference value, a freeze (temporary stop) release instruction is issued to the freeze state file 112 (denoted as THAWED).

  When the kernel 11 receives the function posix_fadvise () from the cache release instruction process 104, if the use of the memory corresponding to the specified file is found in the cache 113, the kernel 11 releases the memory used by the file from the cache 1138. Perform (operation S207).

  In addition, the kernel 11 monitors the freeze state file 112 (operation S208), and if freeze is specified (if FROZEN is described), the backup execution process 105 is frozen (pause) and freeze release is specified. If it is performed (when THAWED is described), the freeze (temporary stop) of the backup execution process 105 is canceled (operation S209).

2.3) Operation of each process In FIG. 4, the backup main process 101 generates the backup target file list 102, the freeze instruction process 103, the cache release instruction process 104, and the backup execution process 105 as described above (operation S301). After that, the process waits for a predetermined time (1 second) until the backup process is completed (operations S305 and S306). When the backup processing process ends (YES in operation S306), the backup main process 101 outputs a freeze instruction process end notification and a cache release instruction process end notification to the freeze instruction process 103 and the cache release instruction process 104, respectively ( Operation S307), the main process is terminated.

  In FIG. 5, the freeze instruction process 103 obtains the current memory usage amount value of the process group 13 specified by cgroup from the memory usage current value file 111 and compares it with the reference value TH1 (operation S401). This reference value TH1 serves as a threshold value for determining whether to give a freeze instruction. The reference value TH1 is set to a value lower than the upper limit value TH2 of the memory used by the process group 13 specified by cgroup.

  When the memory usage is equal to or less than the reference value TH1 (NO in operation S401), it is checked whether the value in the freezer state file 112 is FROZEN or FREEZING (operation S402). If the value of the freezer state file 112 is FROZEN or FREEZING (YES in operation S402), a freeze release instruction is issued (operation S403). Here, the freeze release instruction means writing “THAWED” in the freezer state file 112. If the value of the freezer status file 112 is neither FROZEN nor FREEZING (NO in operation S402), the freeze release instruction (operation S403) is not performed.

  When the memory usage is larger than the reference value TH1 (YES in operation S401), it is checked whether the value of the freezer state file 112 is THAWED (operation S404). If the value of the freezer status file 112 is THAWED (YES in operation S404), a freeze instruction is executed (operation S405). Here, the freeze instruction 4-5 is to write FROZEN to the freezer state file. If the value of the freezer state file 112 is not THAWED (NO in operation S404), the freeze instruction (operation S405) is not performed.

  Thereafter (NO in operation S402, NO in operation S403, NO in operation S404, and after operation S405), the freeze instruction process 103 waits for a predetermined time (1 second) (operation S406), and whether a freeze instruction process end notification has been received. If not received (operation S407), the process from operation S401 is repeated (NO in operation S407). If a freeze instruction process end notification is received, the process ends (YES in operation S407). ). The freeze instruction process ends when the backup main process 101 receives a freeze instruction process end notification. Since this notification is received after the backup execution process 105 is ended, after the freeze instruction process end notification is received, the freeze release process is not necessary.

  In FIG. 6, the cache release instruction process 104 reads the compressed file list 110 (operation S501), and checks whether or not there is a newly added file output (operation S502). If there is a newly added file output (YES in operation S502), “compressed” is entered in the compressed column of the backup target file list 102 for the newly added file (operation S503). Thereafter, as shown in operations S504 to S506, the cache release instruction process 104 performs the same processing as when there is an output even when there is no new additional file output in operation S502 (NO in operation S502).

First, the cache release instruction process 104 looks at the backup target file list 102 and notifies the kernel 11 of a cache release instruction for all files that meet either of the following conditions A and B (operation S504). Refer to FIG. 8A for the backup target file list 102.
Condition A: The lowest file among the files that have "advised" in the fadvise completed column;
Condition B: A file which does not have “advised” in the fadvise completed column and has “compressed” in the compressed column.

  The cache release instruction is notified to the kernel 11 by the function posix_fadvise (). Since this is a format in which only one file is specified by one function execution, the function is executed for the number of files when there are a plurality of files. There is a need to.

  Subsequently, the cache release instruction process 104 puts “advised” in the fadvised column for all files that do not have “advised” in the fadvised column of the backup target file list 102 and have “compressed” in the compressed column. (Operation S505).

Thereafter, it waits for a predetermined time (1 second) (operation S506), determines whether or not a cache release instruction process end notification has been received (operation S507), and if not received (NO in operation S507), described above. Returning to operation S501, the processing of operations S501 to S506 is repeated.
If the cache release instruction process end notification has been received (YES in operation S507), the processing of operations S504 and S505 described above is performed as the end processing, and the process ends (operation S508).

  The cache release instruction process ends when the backup main process 101 receives a cache release instruction process end notification. The reason why the operations S504 and S505 are executed in the termination process in the operation S508 is to immediately release the memory of the backup process file on the cache 113.

  In FIG. 7, the backup execution process 105 executes the following processing for all backup target files (operation S601). That is, execution of compression processing of individual files (operation S602) and output of file names of individual files that have been compressed in the compressed file list 110 (operation S603). This is because, for example, when the -v option is specified with the tar command, the file name for which compression processing is completed each time compression processing for each file is completed before compression processing for all files is completed Is output as a log.

2.4) Files Showing the Status of Backup Processing As illustrated in FIG. 8A, the backup target file list 102 is created immediately after the backup main process 101 is started. Immediately after startup, the compressed column and the fadvise completed column are blank and the file name is described. As described in operation S <b> 503 of FIG. 6, “compressed” is described in the compressed column of the backup target file list 102 for the file newly added to the compressed file list 110. Further, as described in the operation S505 in FIG. 6, all the files that do not have “advised” in the fadvised column of the backup target file list 102 and have “compressed” in the compressed column have “advised” in the fadvised column. "Is written.

  As illustrated in FIG. 8B, the memory usage current value file 111 includes the memory usage current value of the process group (/ cgroup / memory / test in this example) specified by the cgroup memory subsystem. It is filled in.

As illustrated in FIG. 8C, the freezer state file 112 indicates that the process group (/ cgroup / freezer / test in this example) designated by the cgroup freezer subsystem is in one of the following situations: Indicates.
-Process group processing is suspended (FROZEN)
-While the system is executing process group suspension processing (FREEZING)
-Process group is not suspended (THAWED)

The following two values can be written to the freezer status file 112.
-FROZEN (specified when suspending process group processing)
-THAWED (specified when resuming process group processing)

3. Example According to the above-described embodiment, the amount of memory used in the backup process is controlled so as not to exceed the upper limit value. That is, when the memory usage exceeds the reference value TH1, the backup process is stopped, and the corresponding cache is released by executing posix_fadvise (), thereby reducing the memory usage. After the memory usage falls below the reference value TH1, the backup process is resumed. By repeating this operation, the memory usage can be suppressed so as not to exceed the memory upper limit value that can be used by the process group of the backup process. Hereinafter, specific changes in the memory usage will be described with reference to FIG.

  In FIG. 9, when the backup process is started, the backup execution process 105 executes a file compression command (for example, a tar command), thereby increasing the amount of memory used by the process group 13 for the backup process (operation S701). ). Here, a case where only the backup execution process 105 is registered in the backup process group 13 will be described. However, when the backup process is divided into a plurality of processes, only a single process is executed. Instead, the memory limit is enforced by the memory usage of the entire process group. Therefore, it is described below as the memory usage of the entire process group.

  When the memory usage of the process group for backup processing exceeds the reference value TH1, a freeze instruction for stopping the operation of the backup execution process 105 is issued from the freeze instruction process 103 (operation S702). Specifically, as shown in FIG. 8C, when FROZEN is written in the freezer state file 112 (/cgroup/freezer/test/freezer.state), the kernel 11 temporarily stops processing of the backup execution process 105. Let As a result, the increase in the memory usage of the backup execution process 105 is stopped, but the contents of the file referred to by the backup execution process 105 remain secured in the cache memory. Will not drop.

  Therefore, the cache release instruction process 104 releases the contents of the file that has been secured in the cache memory by the cache release instruction. Specifically, a function called posix_fadvise () is called to release the cache for each file (operation S703). The file whose cache is to be released is a file that satisfies either of the above-described conditions A and B among the files described in the backup target file list 102 (see operation S504 in FIG. 6).

  By executing posix_fadvise (), the memory of the backup process target file that has been placed in the cache memory is released, and the memory usage of the process group of the backup process decreases (operation S704). When the memory usage of the process group for backup processing falls below the reference value TH1, the backup execution process 105 resumes processing for executing a file compression command (eg, tar command) (operation S701). Thereafter, by repeating these processes (operations S701 to S704) until the backup process is completed, it is possible to prevent the backup process group from reaching the usable memory upper limit value TH2.

  The memory upper limit TH2 that can be used by the process group of the backup process depends on how much the remaining memory capacity is obtained by subtracting the memory capacity used by processes other than the backup process (for example, call control process) from the physical memory capacity. ,It is determined.

  In cgroup's memory subsystem, there is already a function to set the values of memory.limit_in_bytes (user memory limit) and memory.memsw.limit_in_bytes (user memory + swap limit). If only the limit value is set by the function, the backup execution process 105 may be stopped when the memory upper limit value TH2 is reached, or it may be forcibly terminated by the OOM Killer. If backup control according to this embodiment is implemented, it is not necessary to specify values for memory.limit_in_bytes (upper limit of user memory) and memory.memsw.limit_in_bytes (upper limit of user memory + swap).

  Note that the reference value TH1 of the memory usage should be changed according to the CPU performance and the memory upper limit value that can be used by the backup process group, so that the backup process group does not reach the upper memory limit value that can be used. An appropriate value may be selected after performing the simulation a plurality of times.

4). Effect As described above, according to the embodiment of the present invention, it is possible to control the memory usage of the process group for backup processing so as not to exceed the upper limit value TH2. As a result, when other processing such as call control processing and backup processing are executed simultaneously, it is possible to secure a sufficient memory capacity for performing other processing such as call control processing.

  In the above description, the case where only the backup execution process is included in the process group has been described, but according to the present embodiment, the backup processing function is implemented by a plurality of processes, and the memory usage is reduced by the plurality of processes as a whole. Even in the case of limiting, it is possible to limit the memory usage in the process group.

  The present invention can be applied to an information processing apparatus capable of simultaneously executing a plurality of processes and simultaneously executing backup processing.

10 communication device 11 OS kernel 12 hardware 13 process group 101 backup main process 102 backup target file list 103 freeze instruction process 104 cache release instruction process 105 backup execution process 110 compressed file list 111 memory usage current value file 112 freeze state file 113 cache

Claims (8)

A communication device having a file backup function,
Monitoring means for monitoring whether or not the amount of memory used for backup processing exceeds a predetermined value smaller than the memory upper limit value allocated to the backup processing;
When the memory usage of the backup process exceeds the predetermined value, control means for temporarily stopping the execution of the backup process and releasing a memory area related to the backup process in the cache;
A communication apparatus comprising:   The control means resumes the backup process when the memory usage of the backup process falls below the predetermined value, and thereafter repeats the suspension of the backup process, the release of the memory area, and the restart in order. The communication apparatus according to claim 1. A communication device having a file backup function,
Backup execution means for executing backup processing;
A pause instruction means for pausing the backup process when the amount of memory used for the backup process exceeds a predetermined value smaller than a memory upper limit value allocated to the backup process;
In accordance with the suspension instruction, control means for temporarily suspending backup processing by the backup execution means and releasing a memory area related to the backup processing in the cache;
A communication apparatus comprising:   When the memory usage of the backup process falls below the predetermined value, the control means resumes the backup process by the backup execution means, and thereafter suspends the backup process, releases the memory area, and resumes. The communication apparatus according to claim 3, wherein the communication apparatus repeats sequentially. A backup control method for a communication device having a file backup function,
Monitoring means monitoring whether or not the amount of memory used for backup processing exceeds a predetermined value smaller than the memory upper limit value allocated to the backup processing;
When the memory usage of the backup process exceeds the predetermined value, the control unit temporarily stops the execution of the backup process and releases a memory area related to the backup process in the cache.
A backup control method characterized by that.   The control means resumes the backup process when the memory usage of the backup process falls below the predetermined value, and thereafter repeats the suspension of the backup process, the release of the memory area, and the restart in order. The backup control method according to claim 5. A program for causing a computer to function as a communication device having a file backup function,
A first function for monitoring whether or not the amount of memory used for backup processing exceeds a predetermined value smaller than the memory upper limit value allocated to the backup processing;
A second function of temporarily stopping execution of the backup process and releasing a memory area related to the backup process in the cache when the memory usage of the backup process exceeds the predetermined value;
Is implemented on the computer.   When the memory usage of the backup process decreases below the predetermined value, the second function resumes the backup process, and thereafter, the backup process is suspended, the memory area is released, and the restart is sequentially repeated. The program according to claim 7.

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