[tip:perf/core] perf tools: Don' t stop synthesizing threads when one vanishes

[tip-bot for Arnaldo Carvalho de Melo]

Commit-ID: ba361c92e73c771fcbbbd24c2c03c322e2de2e31
Gitweb: http://git.kernel.org/tip/ba361c92e73c771fcbbbd24c2c03c322e2de2e31
Author: Arnaldo Carvalho de Melo <ac...@redhat.com>
AuthorDate: Wed, 17 Oct 2012 18:50:13 -0300
Committer: Arnaldo Carvalho de Melo <ac...@redhat.com>
CommitDate: Thu, 25 Oct 2012 10:37:15 -0200

perf tools: Don't stop synthesizing threads when one vanishes

The perf_event__synthesize_threads routine synthesizes all the existing
threads in the system, because we don't have any kernel facilities to
ask for PERF_RECORD_{FORK,MMAP,COMM} for existing threads.

It was returning an error as soon as one thread couldn't be synthesized,
which is a bit extreme when, for instance, a forkish workload is
running, like a kernel compile.

Cc: David Ahern <dsa...@gmail.com>
Cc: Frederic Weisbecker <fwei...@gmail.com>
Cc: Jiri Olsa <jo...@redhat.com>
Cc: Mike Galbraith <efa...@gmx.de>
Cc: Namhyung Kim <namh...@gmail.com>
Cc: Paul Mackerras <pau...@samba.org>
Cc: Peter Zijlstra <pet...@infradead.org>
Cc: Stephane Eranian <era...@google.com>
Link: http://lkml.kernel.org/n/tip-i7oas1eodp...@git.kernel.org
Signed-off-by: Arnaldo Carvalho de Melo <ac...@redhat.com>
---
tools/perf/util/event.c | 13 ++++++-------
1 files changed, 6 insertions(+), 7 deletions(-)

diff --git a/tools/perf/util/event.c b/tools/perf/util/event.c
index 0ae444e..ca9ca28 100644
--- a/tools/perf/util/event.c
+++ b/tools/perf/util/event.c
@@ -405,16 +405,15 @@ int perf_event__synthesize_threads(struct perf_tool *tool,

if (*end) /* only interested in proper numerical dirents */
continue;
-
- if (__event__synthesize_thread(comm_event, mmap_event, pid, 1,
- process, tool, machine) != 0) {
- err = -1;
- goto out_closedir;
- }
+ /*
+ * We may race with exiting thread, so don't stop just because
+ * one thread couldn't be synthesized.
+ */
+ __event__synthesize_thread(comm_event, mmap_event, pid, 1,
+ process, tool, machine);
}

err = 0;
-out_closedir:
closedir(proc);
out_free_mmap:
free(mmap_event);
--
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