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author | 2015-05-10 15:13:15 -0400 | |
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committer | 2015-06-07 16:09:06 +0200 | |
commit | c4937a91ea56b546234b0608a413ebad90536d26 (patch) | |
tree | 5bcefc489a99022a8ffb70d5328703286a42885d /tools/perf/util/event.c | |
parent | perf/x86/intel: Introduce PERF_RECORD_LOST_SAMPLES (diff) | |
download | linux-c4937a91ea56b546234b0608a413ebad90536d26.tar.gz linux-c4937a91ea56b546234b0608a413ebad90536d26.tar.bz2 linux-c4937a91ea56b546234b0608a413ebad90536d26.zip |
perf tools: handle PERF_RECORD_LOST_SAMPLES
This patch modifies the perf tool to handle the new RECORD type,
PERF_RECORD_LOST_SAMPLES.
The number of lost-sample events is stored in
.nr_events[PERF_RECORD_LOST_SAMPLES]. The exact number of samples
which the kernel dropped is stored in total_lost_samples.
When the percentage of dropped samples is greater than 5%, a warning
is printed.
Here are some examples:
Eg 1, Recording different frequently-occurring events is safe with the
patch. Only a very low drop rate is associated with such actions.
$ perf record -e '{cycles:p,instructions:p}' -c 20003 --no-time ~/tchain ~/tchain
$ perf report -D | tail
SAMPLE events: 120243
MMAP2 events: 5
LOST_SAMPLES events: 24
FINISHED_ROUND events: 15
cycles:p stats:
TOTAL events: 59348
SAMPLE events: 59348
instructions:p stats:
TOTAL events: 60895
SAMPLE events: 60895
$ perf report --stdio --group
# To display the perf.data header info, please use --header/--header-only options.
#
#
# Total Lost Samples: 24
#
# Samples: 120K of event 'anon group { cycles:p, instructions:p }'
# Event count (approx.): 24048600000
#
# Overhead Command Shared Object Symbol
# ................ ........... ................
..................................
#
99.74% 99.86% tchain_edit tchain_edit [.] f3
0.09% 0.02% tchain_edit tchain_edit [.] f2
0.04% 0.00% tchain_edit [kernel.vmlinux] [k] ixgbe_read_reg
Eg 2, Recording the same thing multiple times can lead to high drop
rate, but it is not a useful configuration.
$ perf record -e '{cycles:p,cycles:p}' -c 20003 --no-time ~/tchain
Warning: Processed 600592 samples and lost 99.73% samples!
[perf record: Woken up 148 times to write data]
[perf record: Captured and wrote 36.922 MB perf.data (1206322 samples)]
[perf record: Woken up 1 times to write data]
[perf record: Captured and wrote 0.121 MB perf.data (1629 samples)]
Signed-off-by: Kan Liang <kan.liang@intel.com>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Cc: Andrew Morton <akpm@linux-foundation.org>
Cc: H. Peter Anvin <hpa@zytor.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: acme@infradead.org
Cc: eranian@google.com
Link: http://lkml.kernel.org/r/1431285195-14269-9-git-send-email-kan.liang@intel.com
Signed-off-by: Ingo Molnar <mingo@kernel.org>
Diffstat (limited to 'tools/perf/util/event.c')
-rw-r--r-- | tools/perf/util/event.c | 9 |
1 files changed, 9 insertions, 0 deletions
diff --git a/tools/perf/util/event.c b/tools/perf/util/event.c index c1925968a8af..793b1503d437 100644 --- a/tools/perf/util/event.c +++ b/tools/perf/util/event.c @@ -25,6 +25,7 @@ static const char *perf_event__names[] = { [PERF_RECORD_SAMPLE] = "SAMPLE", [PERF_RECORD_AUX] = "AUX", [PERF_RECORD_ITRACE_START] = "ITRACE_START", + [PERF_RECORD_LOST_SAMPLES] = "LOST_SAMPLES", [PERF_RECORD_HEADER_ATTR] = "ATTR", [PERF_RECORD_HEADER_EVENT_TYPE] = "EVENT_TYPE", [PERF_RECORD_HEADER_TRACING_DATA] = "TRACING_DATA", @@ -712,6 +713,14 @@ int perf_event__process_itrace_start(struct perf_tool *tool __maybe_unused, return machine__process_itrace_start_event(machine, event); } +int perf_event__process_lost_samples(struct perf_tool *tool __maybe_unused, + union perf_event *event, + struct perf_sample *sample, + struct machine *machine) +{ + return machine__process_lost_samples_event(machine, event, sample); +} + size_t perf_event__fprintf_mmap(union perf_event *event, FILE *fp) { return fprintf(fp, " %d/%d: [%#" PRIx64 "(%#" PRIx64 ") @ %#" PRIx64 "]: %c %s\n", |