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author | Arnaldo Carvalho de Melo <acme@redhat.com> | 2011-01-15 10:40:59 -0200 |
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committer | Arnaldo Carvalho de Melo <acme@redhat.com> | 2011-01-22 19:56:30 -0200 |
commit | 04391debc3e1195222a4dbb162ace6542dd89c1c (patch) | |
tree | 910f12bd4d1f08c37d2086b4c725f50a8dd3c682 /tools/perf/util/evlist.c | |
parent | 98d77b78504a423fca911a26a17bee00ef2fdda2 (diff) | |
download | op-kernel-dev-04391debc3e1195222a4dbb162ace6542dd89c1c.zip op-kernel-dev-04391debc3e1195222a4dbb162ace6542dd89c1c.tar.gz |
perf evlist: Steal mmap reading routine from 'perf top'
Will be used in the upcoming 'perf test' entry for the evlist mmap
routines.
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/evlist.c')
-rw-r--r-- | tools/perf/util/evlist.c | 62 |
1 files changed, 62 insertions, 0 deletions
diff --git a/tools/perf/util/evlist.c b/tools/perf/util/evlist.c index deb82a4..4b3b84c 100644 --- a/tools/perf/util/evlist.c +++ b/tools/perf/util/evlist.c @@ -95,3 +95,65 @@ struct perf_evsel *perf_evlist__id2evsel(struct perf_evlist *evlist, u64 id) return sid->evsel; return NULL; } + +event_t *perf_evlist__read_on_cpu(struct perf_evlist *evlist, int cpu) +{ + /* XXX Move this to perf.c, making it generally available */ + unsigned int page_size = sysconf(_SC_PAGE_SIZE); + struct perf_mmap *md = &evlist->mmap[cpu]; + unsigned int head = perf_mmap__read_head(md); + unsigned int old = md->prev; + unsigned char *data = md->base + page_size; + event_t *event = NULL; + 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 > md->mask / 2 || 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) { + size_t size; + + event = (event_t *)&data[old & md->mask]; + size = event->header.size; + + /* + * Event straddles the mmap boundary -- header should always + * be inside due to u64 alignment of output. + */ + if ((old & md->mask) + size != ((old + size) & md->mask)) { + unsigned int offset = old; + unsigned int len = min(sizeof(*event), size), cpy; + void *dst = &evlist->event_copy; + + do { + cpy = min(md->mask + 1 - (offset & md->mask), len); + memcpy(dst, &data[offset & md->mask], cpy); + offset += cpy; + dst += cpy; + len -= cpy; + } while (len); + + event = &evlist->event_copy; + } + + old += size; + } + + md->prev = old; + return event; +} |