Messages in this thread | | | Subject | Re: [PATCH v2] Poll for monitored tasks being alive in fork mode | From | "Jin, Yao" <> | Date | Mon, 21 Jan 2019 09:40:45 +0800 |
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Hi Arnaldo,
Is this patch acceptable?
Thanks Jin Yao
On 1/7/2019 5:05 PM, Jiri Olsa wrote: > On Mon, Jan 07, 2019 at 09:00:50AM +0800, Jin Yao wrote: >> Following test shows the stat keeps running even if no longer >> task to monitor (mgen exits at ~5s). >> >> perf stat -e cycles -p `pgrep mgen` -I1000 -- sleep 10 >> time counts unit events >> 1.000148916 1,308,365,864 cycles >> 2.000379171 1,297,269,875 cycles >> 3.000556719 1,297,187,078 cycles >> 4.000914241 761,261,827 cycles >> 5.001306091 <not counted> cycles >> 6.001676881 <not counted> cycles >> 7.002046336 <not counted> cycles >> 8.002405651 <not counted> cycles >> 9.002766625 <not counted> cycles >> 10.001395827 <not counted> cycles >> >> We'd better finish stat immediately if there's no longer task to >> monitor. >> >> After: >> >> perf stat -e cycles -p `pgrep mgen` -I1000 -- sleep 10 >> time counts unit events >> 1.000180062 1,236,592,661 cycles >> 2.000421539 1,223,733,572 cycles >> 3.000609910 1,297,047,663 cycles >> 4.000807545 1,297,215,816 cycles >> 5.001001578 1,297,208,032 cycles >> 6.001390345 582,343,659 cycles >> sleep: Terminated >> >> Now the stat exits immediately when the monitored tasks ends. >> >> v2: >> --- >> There is a potential race condition window, that is the >> child_pid set with -1 and kill(-1, SIGTERM) may happen. >> Jiri provides a simple method which stores the child_pid to >> a local variable and check the local variable before kill(). >> At least, we can avoid the kill(-1, SIGTERM) case. >> >> Signed-off-by: Jin Yao <yao.jin@linux.intel.com> > > Reviewed-by: Jiri Olsa <jolsa@kernel.org> > > thanks, > jirka > >> --- >> tools/perf/builtin-stat.c | 9 +++++++++ >> 1 file changed, 9 insertions(+) >> >> diff --git a/tools/perf/builtin-stat.c b/tools/perf/builtin-stat.c >> index 63a3afc..bd5fb8e 100644 >> --- a/tools/perf/builtin-stat.c >> +++ b/tools/perf/builtin-stat.c >> @@ -553,6 +553,15 @@ static int __run_perf_stat(int argc, const char **argv, int run_idx) >> >> if (interval || timeout) { >> while (!waitpid(child_pid, &status, WNOHANG)) { >> + if (!is_target_alive(&target, >> + evsel_list->threads)) { >> + int pid = child_pid; >> + >> + if (pid != -1) >> + kill(pid, SIGTERM); >> + break; >> + } >> + >> nanosleep(&ts, NULL); >> if (timeout) >> break; >> -- >> 2.7.4 >>
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