Messages in this thread Patch in this message | | | Date | Mon, 6 Mar 2017 14:40:17 -0800 | From | Andrew Morton <> | Subject | Re: [PATCH] taskstats: Add e/u/stime for TGID command |
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On Fri, 3 Mar 2017 10:33:44 +0800 Zhang Xiao <xiao.zhang@windriver.com> wrote:
> Add elapsed time, user CPU time and system CPU time to > thread group status request. > > --- a/kernel/taskstats.c > +++ b/kernel/taskstats.c > @@ -210,6 +210,7 @@ static int fill_stats_for_tgid(pid_t tgid, struct taskstats *stats) > struct task_struct *tsk, *first; > unsigned long flags; > int rc = -ESRCH; > + u64 delta, utime, stime; > > /* > * Add additional stats from live tasks except zombie thread group > @@ -238,6 +239,16 @@ static int fill_stats_for_tgid(pid_t tgid, struct taskstats *stats) > */ > delayacct_add_tsk(stats, tsk); > > + /* calculate task elapsed time in nsec */ > + delta = ktime_get_ns() - tsk->start_time; > + /* Convert to micro seconds */ > + do_div(delta, NSEC_PER_USEC); > + stats->ac_etime += delta; > + > + task_cputime(tsk, &utime, &stime); > + stats->ac_utime += div_u64(utime, NSEC_PER_USEC); > + stats->ac_stime += div_u64(stime, NSEC_PER_USEC); > + > stats->nvcsw += tsk->nvcsw; > stats->nivcsw += tsk->nivcsw; > } while_each_thread(first, tsk);
hm, OK, we were just leaving these at zero. Seems sane to me.
It would be more efficient and perhaps more deterministic to sample ktime just once?
--- a/kernel/taskstats.c~taskstats-add-e-u-stime-for-tgid-command-fix +++ a/kernel/taskstats.c @@ -211,6 +211,7 @@ static int fill_stats_for_tgid(pid_t tgi unsigned long flags; int rc = -ESRCH; u64 delta, utime, stime; + u64 start_time; /* * Add additional stats from live tasks except zombie thread group @@ -228,6 +229,7 @@ static int fill_stats_for_tgid(pid_t tgi memset(stats, 0, sizeof(*stats)); tsk = first; + start_time = ktime_get_ns(); do { if (tsk->exit_state) continue; @@ -240,7 +242,7 @@ static int fill_stats_for_tgid(pid_t tgi delayacct_add_tsk(stats, tsk); /* calculate task elapsed time in nsec */ - delta = ktime_get_ns() - tsk->start_time; + delta = start_time - tsk->start_time; /* Convert to micro seconds */ do_div(delta, NSEC_PER_USEC); stats->ac_etime += delta; _
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