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diff --git a/Documentation/accounting/taskstats-struct.rst b/Documentation/accounting/taskstats-struct.rst new file mode 100644 index 000000000000..ca90fd489c9a --- /dev/null +++ b/Documentation/accounting/taskstats-struct.rst @@ -0,0 +1,199 @@ +==================== +The struct taskstats +==================== + +This document contains an explanation of the struct taskstats fields. + +There are three different groups of fields in the struct taskstats: + +1) Common and basic accounting fields + If CONFIG_TASKSTATS is set, the taskstats interface is enabled and + the common fields and basic accounting fields are collected for + delivery at do_exit() of a task. +2) Delay accounting fields + These fields are placed between:: + + /* Delay accounting fields start */ + + and:: + + /* Delay accounting fields end */ + + Their values are collected if CONFIG_TASK_DELAY_ACCT is set. +3) Extended accounting fields + These fields are placed between:: + + /* Extended accounting fields start */ + + and:: + + /* Extended accounting fields end */ + + Their values are collected if CONFIG_TASK_XACCT is set. + +4) Per-task and per-thread context switch count statistics + +5) Time accounting for SMT machines + +6) Extended delay accounting fields for memory reclaim + +Future extension should add fields to the end of the taskstats struct, and +should not change the relative position of each field within the struct. + +:: + + struct taskstats { + +1) Common and basic accounting fields:: + + /* The version number of this struct. This field is always set to + * TAKSTATS_VERSION, which is defined in <linux/taskstats.h>. + * Each time the struct is changed, the value should be incremented. + */ + __u16 version; + + /* The exit code of a task. */ + __u32 ac_exitcode; /* Exit status */ + + /* The accounting flags of a task as defined in <linux/acct.h> + * Defined values are AFORK, ASU, ACOMPAT, ACORE, and AXSIG. + */ + __u8 ac_flag; /* Record flags */ + + /* The value of task_nice() of a task. */ + __u8 ac_nice; /* task_nice */ + + /* The name of the command that started this task. */ + char ac_comm[TS_COMM_LEN]; /* Command name */ + + /* The scheduling discipline as set in task->policy field. */ + __u8 ac_sched; /* Scheduling discipline */ + + __u8 ac_pad[3]; + __u32 ac_uid; /* User ID */ + __u32 ac_gid; /* Group ID */ + __u32 ac_pid; /* Process ID */ + __u32 ac_ppid; /* Parent process ID */ + + /* The time when a task begins, in [secs] since 1970. */ + __u32 ac_btime; /* Begin time [sec since 1970] */ + + /* The elapsed time of a task, in [usec]. */ + __u64 ac_etime; /* Elapsed time [usec] */ + + /* The user CPU time of a task, in [usec]. */ + __u64 ac_utime; /* User CPU time [usec] */ + + /* The system CPU time of a task, in [usec]. */ + __u64 ac_stime; /* System CPU time [usec] */ + + /* The minor page fault count of a task, as set in task->min_flt. */ + __u64 ac_minflt; /* Minor Page Fault Count */ + + /* The major page fault count of a task, as set in task->maj_flt. */ + __u64 ac_majflt; /* Major Page Fault Count */ + + +2) Delay accounting fields:: + + /* Delay accounting fields start + * + * All values, until the comment "Delay accounting fields end" are + * available only if delay accounting is enabled, even though the last + * few fields are not delays + * + * xxx_count is the number of delay values recorded + * xxx_delay_total is the corresponding cumulative delay in nanoseconds + * + * xxx_delay_total wraps around to zero on overflow + * xxx_count incremented regardless of overflow + */ + + /* Delay waiting for cpu, while runnable + * count, delay_total NOT updated atomically + */ + __u64 cpu_count; + __u64 cpu_delay_total; + + /* Following four fields atomically updated using task->delays->lock */ + + /* Delay waiting for synchronous block I/O to complete + * does not account for delays in I/O submission + */ + __u64 blkio_count; + __u64 blkio_delay_total; + + /* Delay waiting for page fault I/O (swap in only) */ + __u64 swapin_count; + __u64 swapin_delay_total; + + /* cpu "wall-clock" running time + * On some architectures, value will adjust for cpu time stolen + * from the kernel in involuntary waits due to virtualization. + * Value is cumulative, in nanoseconds, without a corresponding count + * and wraps around to zero silently on overflow + */ + __u64 cpu_run_real_total; + + /* cpu "virtual" running time + * Uses time intervals seen by the kernel i.e. no adjustment + * for kernel's involuntary waits due to virtualization. + * Value is cumulative, in nanoseconds, without a corresponding count + * and wraps around to zero silently on overflow + */ + __u64 cpu_run_virtual_total; + /* Delay accounting fields end */ + /* version 1 ends here */ + + +3) Extended accounting fields:: + + /* Extended accounting fields start */ + + /* Accumulated RSS usage in duration of a task, in MBytes-usecs. + * The current rss usage is added to this counter every time + * a tick is charged to a task's system time. So, at the end we + * will have memory usage multiplied by system time. Thus an + * average usage per system time unit can be calculated. + */ + __u64 coremem; /* accumulated RSS usage in MB-usec */ + + /* Accumulated virtual memory usage in duration of a task. + * Same as acct_rss_mem1 above except that we keep track of VM usage. + */ + __u64 virtmem; /* accumulated VM usage in MB-usec */ + + /* High watermark of RSS usage in duration of a task, in KBytes. */ + __u64 hiwater_rss; /* High-watermark of RSS usage */ + + /* High watermark of VM usage in duration of a task, in KBytes. */ + __u64 hiwater_vm; /* High-water virtual memory usage */ + + /* The following four fields are I/O statistics of a task. */ + __u64 read_char; /* bytes read */ + __u64 write_char; /* bytes written */ + __u64 read_syscalls; /* read syscalls */ + __u64 write_syscalls; /* write syscalls */ + + /* Extended accounting fields end */ + +4) Per-task and per-thread statistics:: + + __u64 nvcsw; /* Context voluntary switch counter */ + __u64 nivcsw; /* Context involuntary switch counter */ + +5) Time accounting for SMT machines:: + + __u64 ac_utimescaled; /* utime scaled on frequency etc */ + __u64 ac_stimescaled; /* stime scaled on frequency etc */ + __u64 cpu_scaled_run_real_total; /* scaled cpu_run_real_total */ + +6) Extended delay accounting fields for memory reclaim:: + + /* Delay waiting for memory reclaim */ + __u64 freepages_count; + __u64 freepages_delay_total; + +:: + + } |