发自我的 iPhone
> 在 2015年10月23日，下午9:51，Arnaldo Carvalho de Melo <[email protected]> 写道： > > Em Fri, Oct 23, 2015 at 10:43:49AM +0000, Wang Nan escreveu: >> Inherit bit is useless for a system wide evsel [1]. Further kernel >> improvements are giving more constrain [2] on inherit events. This >> patch set inherit bit to 0 to avoid potential constrains. >> >> [1] >> http://lkml.kernel.org/r/[email protected] >> [2] http://lkml.kernel.org/r/[email protected] >> >> Signed-off-by: Wang Nan <[email protected]> >> Cc: Arnaldo Carvalho de Melo <[email protected]> >> Cc: Alexei Starovoitov <[email protected]> >> Cc: Peter Zijlstra <[email protected]> >> Cc: Li Zefan <[email protected]> >> Cc: [email protected] >> Link: http://lkml.kernel.org/n/[email protected] >> --- >> >> evsel->system_wide doesn't correct reflect whether this evsel is system >> wide or not, so checks pid when invoking perf_event_open, and it is >> always correct. > > Can't we do this at perf_evlist__config() or perf_evsel__config() time? perf_evlist_config() is excluded because perf record doesn't use it. > > We have record_opts at perf_evsel__config() time and I think we should > leave changing the attr at perf_evsel__open() time for feature > fallbacks, i.e. something we will only know when trying to use, which is > different from this inherit-on-syswide case, that we know far in advance > we will not need. I tried to set this bit based on evsel->system_wide but it seems not reliable as it should be, so I was wondering whether it is designed for other use. I will look into this next week. Thank you. > > - Arnaldo > >> --- >> tools/perf/util/evsel.c | 6 +++++- >> 1 file changed, 5 insertions(+), 1 deletion(-) >> >> diff --git a/tools/perf/util/evsel.c b/tools/perf/util/evsel.c >> index 5566b16..e2d6c9a 100644 >> --- a/tools/perf/util/evsel.c >> +++ b/tools/perf/util/evsel.c >> @@ -1337,6 +1337,7 @@ retry_sample_id: >> >> for (thread = 0; thread < nthreads; thread++) { >> int group_fd; >> + struct perf_event_attr attr; >> >> if (!evsel->cgrp && !evsel->system_wide) >> pid = thread_map__pid(threads, thread); >> @@ -1346,7 +1347,10 @@ retry_open: >> pr_debug2("sys_perf_event_open: pid %d cpu %d group_fd %d >> flags %#lx\n", >> pid, cpus->map[cpu], group_fd, flags); >> >> - FD(evsel, cpu, thread) = sys_perf_event_open(&evsel->attr, >> + attr = evsel->attr; >> + if (pid == -1) >> + attr.inherit = 0; >> + FD(evsel, cpu, thread) = sys_perf_event_open(&attr, >> pid, >> cpus->map[cpu], >> group_fd, flags); >> -- >> 1.8.3.4 -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to [email protected] More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
