Messages in this thread | | | From | Jiri Olsa <> | Subject | [RFC 00/10] perf: Add build id parsing fault detection/fix | Date | Tue, 22 Jun 2021 17:39:08 +0200 |
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hi, this *RFC* patchset adds support to detect faults during mmap2's build id parsing and a way to fix such maps in generated perf.data.
It adds support to record build id faults count for session and store it in perf.data and perf inject support to find these maps and reads build ids for them in user space.
It's probably best explained by the workflow:
Record data with --buildid-mmap option:
# perf record --buildid-mmap ... ... [ perf record: Woken up 1 times to write data ] [ perf record: Failed to parse 4 build ids] [ perf record: Captured and wrote 0.008 MB perf.data ]
Check if there's any build id fault reported:
# perf report --header-only ... # build id mmap stats: FAULTS 4, LOST 0, NOT FIXED
There is, check the stats:
# perf report --stat
Aggregated stats: TOTAL events: 104 .... BUILD_ID fails: 4 (14.3%)
Yep, let's fix it:
# perf inject --buildid-mmap2 -i perf.data -o perf-fixed.data
And verify:
# perf report -i perf-fixed.data --stats
Aggregated stats: TOTAL events: 104 ....
Good, let's see how many we fixed:
# perf report --header-only -i perf-fixed.data ... # build id mmap stats: FAULTS 4, LOST 0, FIXED(4)
I don't have a good way to test it, just by artificially adding the faults in kernel code, but Ian and Namhyung might have setup that could generate that.. would be great to have a perf test for this.
Also available in here: git://git.kernel.org/pub/scm/linux/kernel/git/jolsa/perf.git perf/buildid_stats
thoughts?
thanks, jirka
--- Jiri Olsa (10): perf: Track build id faults for mmap2 event perf: Move build_id_parse to check only regular files perf: Add new read_format bit to read build id faults perf: Add new read_format bit to read lost events tools: Sync perf_event.h uapi libperf: Do not allow PERF_FORMAT_GROUP in perf_evsel__read perf record: Add support to read build id fails perf record: Add new HEADER_BUILD_ID_MMAP feature perf report: Display build id fails stats perf inject: Add --buildid-mmap2 option to fix failed build ids
include/linux/perf_event.h | 2 ++ include/uapi/linux/perf_event.h | 20 +++++++++++++------- kernel/events/core.c | 49 +++++++++++++++++++++++++++++++++++++++++++------ kernel/events/ring_buffer.c | 3 +++ tools/include/uapi/linux/perf_event.h | 20 +++++++++++++------- tools/lib/perf/evsel.c | 10 ++++++++++ tools/lib/perf/include/perf/evsel.h | 11 ++++++++++- tools/perf/Documentation/perf-inject.txt | 3 +++ tools/perf/Documentation/perf.data-file-format.txt | 19 +++++++++++++++++++ tools/perf/builtin-inject.c | 45 +++++++++++++++++++++++++++++++++++++++++++-- tools/perf/builtin-record.c | 97 +++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++ tools/perf/builtin-report.c | 35 +++++++++++++++++++++++++++++++++++ tools/perf/util/env.h | 6 ++++++ tools/perf/util/evsel.c | 12 ++++++++++++ tools/perf/util/header.c | 80 ++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++ tools/perf/util/header.h | 1 + tools/perf/util/map.h | 15 +++++++++++++++ tools/perf/util/perf_event_attr_fprintf.c | 3 ++- 18 files changed, 407 insertions(+), 24 deletions(-)
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