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author | Kan Liang <kan.liang@intel.com> | 2015-05-10 22:13:15 +0300 |
---|---|---|
committer | Ingo Molnar <mingo@kernel.org> | 2015-06-07 17:09:06 +0300 |
commit | c4937a91ea56b546234b0608a413ebad90536d26 (patch) | |
tree | 5bcefc489a99022a8ffb70d5328703286a42885d /tools/perf/util/event.h | |
parent | f38b0dbb491a6987e198aa6b428db8692a6480f8 (diff) | |
download | linux-c4937a91ea56b546234b0608a413ebad90536d26.tar.xz |
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.h')
-rw-r--r-- | tools/perf/util/event.h | 17 |
1 files changed, 17 insertions, 0 deletions
diff --git a/tools/perf/util/event.h b/tools/perf/util/event.h index 97179abc80a1..5dc51ada05df 100644 --- a/tools/perf/util/event.h +++ b/tools/perf/util/event.h @@ -52,6 +52,11 @@ struct lost_event { u64 lost; }; +struct lost_samples_event { + struct perf_event_header header; + u64 lost; +}; + /* * PERF_FORMAT_ENABLED | PERF_FORMAT_RUNNING | PERF_FORMAT_ID */ @@ -235,6 +240,12 @@ enum auxtrace_error_type { * total_lost tells exactly how many events the kernel in fact lost, i.e. it is * the sum of all struct lost_event.lost fields reported. * + * The kernel discards mixed up samples and sends the number in a + * PERF_RECORD_LOST_SAMPLES event. The number of lost-samples events is stored + * in .nr_events[PERF_RECORD_LOST_SAMPLES] while total_lost_samples tells + * exactly how many samples the kernel in fact dropped, i.e. it is the sum of + * all struct lost_samples_event.lost fields reported. + * * The total_period is needed because by default auto-freq is used, so * multipling nr_events[PERF_EVENT_SAMPLE] by a frequency isn't possible to get * the total number of low level events, it is necessary to to sum all struct @@ -244,6 +255,7 @@ struct events_stats { u64 total_period; u64 total_non_filtered_period; u64 total_lost; + u64 total_lost_samples; u64 total_invalid_chains; u32 nr_events[PERF_RECORD_HEADER_MAX]; u32 nr_non_filtered_samples; @@ -342,6 +354,7 @@ union perf_event { struct comm_event comm; struct fork_event fork; struct lost_event lost; + struct lost_samples_event lost_samples; struct read_event read; struct throttle_event throttle; struct sample_event sample; @@ -390,6 +403,10 @@ int perf_event__process_lost(struct perf_tool *tool, union perf_event *event, struct perf_sample *sample, struct machine *machine); +int perf_event__process_lost_samples(struct perf_tool *tool, + union perf_event *event, + struct perf_sample *sample, + struct machine *machine); int perf_event__process_aux(struct perf_tool *tool, union perf_event *event, struct perf_sample *sample, |