On Tue, 2011-02-22 at 09:10 +0000, tip-bot for Arnaldo Carvalho de Melo wrote: > Commit-ID: e603dc15072c7fec0ae263597e6dabc3bb4c5c5b > Gitweb: http://git.kernel.org/tip/e603dc15072c7fec0ae263597e6dabc3bb4c5c5b > Author: Arnaldo Carvalho de Melo <acme@xxxxxxxxxx> > AuthorDate: Mon, 21 Feb 2011 16:05:50 -0300 > Committer: Arnaldo Carvalho de Melo <acme@xxxxxxxxxx> > CommitDate: Mon, 21 Feb 2011 22:27:59 -0300 > > perf evsel: Fix inverted test for fixing up attr.inherit flag > > The kernel refuses mmapping an event with the inherit flag set for > something that is systemwide (cpu == -1), and the evsel layer got this > reversed at some point, fix it. > > The symtom was that the --pid and --tid parameters for 'perf record' and > 'perf top' returned with -EINVAL, like: > > # /tmp/build-perf/perf record -v -fo/tmp/perf.data -p 1042 > Warning: ... trying to fall back to cpu-clock-ticks > > Fatal: failed to mmap with 22 (Invalid argument) > > Reported-by: David Ahern <dsahern@xxxxxxxxx> > Cc: Frederic Weisbecker <fweisbec@xxxxxxxxx> > Cc: Ingo Molnar <mingo@xxxxxxx> > Cc: Mike Galbraith <efault@xxxxxx> > Cc: Paul Mackerras <paulus@xxxxxxxxx> > Cc: Peter Zijlstra <peterz@xxxxxxxxxxxxx> > Cc: Stephane Eranian <eranian@xxxxxxxxxx> > Cc: Tom Zanussi <tzanussi@xxxxxxxxx> > LKML-Reference: <new-submission> > Signed-off-by: Arnaldo Carvalho de Melo <acme@xxxxxxxxxx> > --- > tools/perf/util/evsel.c | 15 +++++++++++++-- > 1 files changed, 13 insertions(+), 2 deletions(-) > > diff --git a/tools/perf/util/evsel.c b/tools/perf/util/evsel.c > index 63cadaf..8083d51 100644 > --- a/tools/perf/util/evsel.c > +++ b/tools/perf/util/evsel.c > @@ -179,8 +179,19 @@ static int __perf_evsel__open(struct perf_evsel *evsel, struct cpu_map *cpus, > > for (cpu = 0; cpu < cpus->nr; cpu++) { > int group_fd = -1; > - > - evsel->attr.inherit = (cpus->map[cpu] < 0) && inherit; > + /* > + * Don't allow mmap() of inherited per-task counters. This > + * would create a performance issue due to all children writing > + * to the same buffer. > + * > + * FIXME: > + * Proper fix is not to pass 'inherit' to perf_evsel__open*, > + * but a 'flags' parameter, with 'group' folded there as well, > + * then introduce a PERF_O_{MMAP,GROUP,INHERIT} enum, and if > + * O_MMAP is set, emit a warning if cpu < 0 and O_INHERIT is > + * set. Lets go for the minimal fix first tho. > + */ > + evsel->attr.inherit = (cpus->map[cpu] >= 0) && inherit; > This wrecked perf-stat, perf-stat doesn't mmap and its perfectly fine for it to use task-bound counters with inheritance. -- To unsubscribe from this list: send the line "unsubscribe linux-tip-commits" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html