diff options
| author | Arnaldo Carvalho de Melo <acme@redhat.com> | 2011-01-28 14:49:19 -0200 |
|---|---|---|
| committer | Arnaldo Carvalho de Melo <acme@redhat.com> | 2011-01-29 16:23:58 -0200 |
| commit | dc82009aac6ee6e423b48de43a251745c62ab012 (patch) | |
| tree | 0f3a37aa7340a173f822e60e77e8c8bd5d520a7d /tools | |
| parent | 54489c189b1a0c10eaf21c6d2c5916b50442c871 (diff) | |
perf record: No need to check for overwrites
As we open the mmap with (PROT_READ | PROT_WRITE), signalling the kernel
with perf_mmap__write_tail() when consuming data, so the kernel will not
overwrite.
Suggested-by: Peter Zijlstra <peterz@infradead.org>
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')
| -rw-r--r-- | tools/perf/builtin-record.c | 22 |
1 files changed, 3 insertions, 19 deletions
diff --git a/tools/perf/builtin-record.c b/tools/perf/builtin-record.c index d7886307f6f4..caf927978d92 100644 --- a/tools/perf/builtin-record.c +++ b/tools/perf/builtin-record.c @@ -115,27 +115,11 @@ static void mmap_read(struct perf_mmap *md) unsigned char *data = md->base + page_size; unsigned long size; void *buf; - int diff; - /* - * If we're further behind than half the buffer, there's a chance - * the writer will bite our tail and mess up the samples under us. - * - * If we somehow ended up ahead of the head, we got messed up. - * - * In either case, truncate and restart at head. - */ - diff = head - old; - if (diff < 0) { - fprintf(stderr, "WARNING: failed to keep up with mmap data\n"); - /* - * head points to a known good entry, start there. - */ - old = head; - } + if (old == head) + return; - if (old != head) - samples++; + samples++; size = head - old; |