diff options
| author | Arnaldo Carvalho de Melo <acme@redhat.com> | 2011-02-21 16:05:50 -0300 |
|---|---|---|
| committer | Arnaldo Carvalho de Melo <acme@redhat.com> | 2011-02-21 22:27:59 -0300 |
| commit | e603dc15072c7fec0ae263597e6dabc3bb4c5c5b (patch) | |
| tree | a4fa6e1a548570ce71b8ed97399933de7303c321 /tools/perf/util/evsel.c | |
| parent | fbee632d0ca9f4073a3fefb9a843eac8af036b0f (diff) | |
| download | linux-e603dc15072c7fec0ae263597e6dabc3bb4c5c5b.tar.gz linux-e603dc15072c7fec0ae263597e6dabc3bb4c5c5b.tar.bz2 linux-e603dc15072c7fec0ae263597e6dabc3bb4c5c5b.zip | |
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@gmail.com>
Cc: Frederic Weisbecker <fweisbec@gmail.com>
Cc: Ingo Molnar <mingo@elte.hu>
Cc: Mike Galbraith <efault@gmx.de>
Cc: Paul Mackerras <paulus@samba.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Stephane Eranian <eranian@google.com>
Cc: Tom Zanussi <tzanussi@gmail.com>
LKML-Reference: <new-submission>
Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>
Diffstat (limited to 'tools/perf/util/evsel.c')
| -rw-r--r-- | 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 63cadaf3e208..8083d5126fca 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; for (thread = 0; thread < threads->nr; thread++) { |