Hello Balbir, On Fri, 2010-12-03 at 13:03 +0530, Balbir Singh wrote: > * Oleg Nesterov <oleg@xxxxxxxxxx> [2010-12-01 19:51:28]: > > > On 11/29, Michael Holzheu wrote: [snip] > > Say, taskstats_exit()->fill_stats()->bacct_add_tsk(). Every thread > > does this, including the group_leader. But, it is possible that > > group_leader exits first, before other threads. IOW, what > > stats->ac_cXtime actually mean? > > > > stats->ac_* time was designed only for tgid's to begin with, You mean for tids (threads/tasks), no? stats->ac_* time is only reported for threads in bacct_add_tsk() and not for tgids. > so I am > not sure if ac_cXtime makes sense for threads I would suggest to do it the same way as /proc/<tgid>/tasks/<tid>/stat. It reports the (same) cumulative time for each thread. See do_task_stat() in fs/proc/array.c. So IMHO also for taskstats it makes sense to include the cXtime for all threads and not only for the thread group leader. Also I would include tgid in taskstats so that userspace can group the tasks into thread groups. I am not sure regarding the aggregation for tgids in TASKSTATS_CMD_ATTR_TGID and exit events with group_dead=1. Currently only the delay accounting numbers are aggregated. If we would do it like /proc/<tgid>/stat (do_task_stat() with whole=1) we also could aggregate also the other values e.g. the CPU time. I think the following tgid data would make sense to be returned for TASKSTATS_CMD_ATTR_TGID and exit events with group_dead=1: bacct_add_tsk(): ---------------- ac_pid thread group leader (tsk->tgid) ac_etime thread group leader ac_btime thread group leader ac_nice thread group leader ac_sched thread group leader ac_uid thread group leader ac_gid thread group leader ac_ppid thread group leader ac_comm thread group leader ac_exit_code thread group leader ac_flags thread group leader ac_utimescaled ?? ac_stimescaled ?? ac_utime sum for all live threads + cdata_threads ac_stime sum for all live threads + cdata_threads ac_minflt sum for all live threads + cdata_threads ac_majflt sum for all live threads + cdata_threads new: ac_cutime cdata_wait ac_cstime cdata_wait ac_tgid thread group leader xacct_add_tsk(): ---------------- coremem ? virtmem ? hiwater_rss thread group leader hiwater_vm thread group leader read_char sum for all live threads + tsk->signal.ioac write_char sum for all live threads + tsk->signal.ioac read_syscalls sum for all live threads + tsk->signal.ioac write_syscalls sum for all live threads + tsk->signal.ioac read_bytes sum for all live threads + tsk->signal.ioac write bytes sum for all live threads + tsk->signal.ioac cancelled_write_bytes sum for all live threads + tsk->signal.ioac If we leave everything as it currently is for tgid accounting, we probably should also not include the cXtime for tgids and just include the data for threads (TASKSTATS_CMD_ATTR_PID and task exit events). What do you think? Michael -- To unsubscribe from this list: send the line "unsubscribe linux-s390" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
