PIDSTAT(1)

NAME
pidstat - Report statistics for Linux tasks.

SYNOPSIS
pidstat [ -C comm ] [ -d ] [ -I ] [ -p { pid | SELF | ALL } ] [ -r ] [ -t ] [ -T { TASK | CHILD | ALL } ] [ -u ] [ -V ] [ -w ] [ interval [ count ] ]

DESCRIPTION
The pidstat command is used for monitoring individual tasks currently being managed by the Linux kernel. It writes to standard output activities for every task selected with option -p or for every task managed by the Linux kernel if option -p ALL has been used. Not selecting any tasks is equivalent to specifying -p ALL but only active tasks (tasks with non-zero statistics values) will appear in the report.

The pidstat command can also be used for monitoring the child processes of selected tasks. Read about option -T below.

The interval parameter specifies the amount of time in seconds between each report. A value of 0 (or no parameters at all) indicates that tasks statistics are to be reported for the time since system startup (boot). The count parameter can be specified in conjunction with the interval parameter if this one is not set to zero. The value of count determines the number of reports generated at interval seconds apart. If the interval parameter is specified without the count parameter, the pidstat command generates reports continuously.

You can select information about specific task activities using flags. Not specifying any flags selects only CPU activity.

OPTIONS

-C comm
    Display only tasks whose command name includes the string comm.

-d  Report I/O statistics (kernels 2.6.20 and later only). The following values are displayed:

    PID
        The identification number of the task being monitored.

    kB_rd/s
        Number of kilobytes the task has caused to be read from disk per second.

    kB_wr/s
        Number of kilobytes the task has caused, or shall cause to be written to disk per second.

    kB_ccwr/s
        Number of kilobytes whose writing to disk has been cancelled by the task. This may occur when the task truncates some dirty pagecache. In this case, some IO which another task has been accounted for will not be happening.

    Command
        The command name of the task.

-I  In an SMP environment, indicate that tasks CPU usage (as displayed by option -u ) should be divided by the total number of processors.

-p { pid | SELF | ALL }
    Select tasks (processes) for which statistics are to be reported. pid is the process identification number. The SELF keyword indicates that statistics are to be reported for the pidstat process itself, whereas the ALL keyword indicates that statistics are to be reported for all the tasks managed by the system.

-r  Report page faults and memory utilization.

    When reporting statistics for individual tasks, the following values are displayed:

    PID
        The identification number of the task being monitored.

    minflt/s
        Total number of minor faults the task has made per second, those which have not required loading a memory page from disk.

    majflt/s
        Total number of major faults the task has made per second, those which have required loading a memory page from disk.

    VSZ
        Virtual Size: The virtual memory usage of entire task in kilobytes.

    RSS
        Resident Set Size: The non-swapped physical memory used by the task in kilobytes.

    Command
        The command name of the task.

    When reporting global statistics for tasks and all their children, the following values are displayed:

    PID
        The identification number of the task which is being monitored together with its children.

    minflt-nr
        Total number of minor faults made by the task and all its children, and collected during the interval of time.

    majflt-nr
        Total number of major faults made by the task and all its children, and collected during the interval of time.

    Command
        The command name of the task which is being monitored together with its children.

-t  Also display statistics for threads associated with selected tasks.

    This option adds the following value to the reports:

    TID
        The identification number of the thread being monitored.

-T { TASK | CHILD | ALL }
    This option specifies what has to be monitored by the pidstat command. The TASK keyword indicates that statistics are to be reported for individual tasks (this is the default option) whereas the CHILD keyword indicates that statistics are to be globally reported for the selected tasks and all their children. The ALL keyword indicates that statistics are to be reported for individual tasks and globally for the selected tasks and their children.

    Note: Global statistics for tasks and all their children are not available for all options of pidstat. Also these statistics are not necessarily relevant to current time interval: The statistics of a child process are collected only when it finishes or it is killed.

-u  Report CPU utilization.

    When reporting statistics for individual tasks, the following values are displayed:

    PID
        The identification number of the task being monitored.

    %user
        Percentage of CPU used by the task while executing at the user level (application), with or without nice priority.

    %system
        Percentage of CPU used by the task while executing at the system level (kernel).

    %CPU
        Total percentage of CPU time used by the task. In an SMP environment, the task's CPU usage will be divided by the total number of CPU's if option -I has been entered on the command line.

    CPU
        Processor number to which the task is attached.

    Command
        The command name of the task.

    When reporting global statistics for tasks and all their children, the following values are displayed:

    PID
        The identification number of the task which is being monitored together with its children.

    user-ms
        Total number of milliseconds spent by the task and all its children while executing at the user level (application), with or without nice priority, and collected during the interval of time.

    system-ms
        Total number of milliseconds spent by the task and all its children while executing at the system level (kernel), and collected during the interval of time.

    Command
        The command name of the task which is being monitored together with its children.

-V  Print version number then exit.

-w  Report task switching activity (kernels 2.6.23 and later only). The following values are displayed:

    PID
        The identification number of the task being monitored.

    cswch/s
        Total number of voluntary context switches the task made per second. A voluntary context switch occurs when a task blocks because it requires a resource that is unavailable.

    nvcswch/s
        Total number of non voluntary context switches the task made per second. A involuntary context switch takes place when a task executes for the duration of its time slice and then is forced to relinquish the processor.

    Command
        The command name of the task.

ENVIRONMENT
The pidstat command takes into account the following environment variable:

S_TIME_FORMAT
    If this variable exists and its value is ISO then the current locale will be ignored when printing the date in the report header. The pidstat command will use the ISO 8601 format (YYYY-MM-DD) instead.

EXAMPLES
pidstat 2 5
    Display five reports of CPU statistics for every active task in the system at two second intervals.

pidstat -r -p 1643 2 5
    Display five reports of page faults and memory statistics for PID 1643 at two second intervals.

pidstat -T CHILD -r 2 5
    Display five reports of page faults statistics at two second intervals for the child processes of all tasks in the system. Only child processes with non-zero statistics values are displayed.

BUGS
/proc filesystem must be mounted for the pidstat command to work.

FILES
/proc contains various files with system statistics.

AUTHOR
Sebastien Godard (sysstat <at> orange.fr)

SEE ALSO
sar(1), top(1), ps(1), mpstat(1), iostat(1), vmstat(8)

http://pagesperso-orange.fr/sebastien.godard/