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Message-ID: <ZzuH-8ZCa7BVt3ef@google.com> Date: Mon, 18 Nov 2024 10:31:23 -0800 From: Namhyung Kim <namhyung@...nel.org> To: Ian Rogers <irogers@...gle.com> Cc: Peter Zijlstra <peterz@...radead.org>, Ingo Molnar <mingo@...hat.com>, Arnaldo Carvalho de Melo <acme@...nel.org>, Mark Rutland <mark.rutland@....com>, Alexander Shishkin <alexander.shishkin@...ux.intel.com>, Jiri Olsa <jolsa@...nel.org>, Adrian Hunter <adrian.hunter@...el.com>, Kan Liang <kan.liang@...ux.intel.com>, Athira Jajeev <atrajeev@...ux.vnet.ibm.com>, James Clark <james.clark@...aro.org>, Dominique Martinet <asmadeus@...ewreck.org>, Yang Li <yang.lee@...ux.alibaba.com>, Colin Ian King <colin.i.king@...il.com>, Yang Jihong <yangjihong@...edance.com>, "Steinar H. Gunderson" <sesse@...gle.com>, Oliver Upton <oliver.upton@...ux.dev>, Ilkka Koskinen <ilkka@...amperecomputing.com>, Ze Gao <zegao2021@...il.com>, Weilin Wang <weilin.wang@...el.com>, Ben Gainey <ben.gainey@....com>, zhaimingbing <zhaimingbing@...s.chinamobile.com>, Zixian Cai <fzczx123@...il.com>, Andi Kleen <ak@...ux.intel.com>, Paran Lee <p4ranlee@...il.com>, Thomas Falcon <thomas.falcon@...el.com>, linux-kernel@...r.kernel.org, linux-perf-users@...r.kernel.org, "Steven Rostedt (Google)" <rostedt@...dmis.org> Subject: Re: [PATCH v4 0/6] Avoid parsing tracepoint format just for id On Wed, Nov 13, 2024 at 10:06:13AM -0800, Ian Rogers wrote: > On Sat, Nov 9, 2024 at 9:04 AM Namhyung Kim <namhyung@...nel.org> wrote: > > > > On Sat, Nov 09, 2024 at 08:26:20AM -0800, Ian Rogers wrote: > > > On Fri, Nov 8, 2024 at 10:45 PM Namhyung Kim <namhyung@...nel.org> wrote: > > > > On Fri, Nov 08, 2024 at 10:47:45AM -0800, Ian Rogers wrote: > > > > > Ian Rogers (6): > > > > > tool api fs: Correctly encode errno for read/write open failures > > > > > perf trace-event: Constify print arguments > > > > > perf trace-event: Always build trace-event-info.c > > > > > perf evsel: Add/use accessor for tp_format > > > > > perf evsel: Allow evsel__newtp without libtraceevent > > > > > perf tests: Enable tests disabled due to tracepoint parsing > > > > > > > > After applying this series, I'm seeing some test failures. But I don't > > > > understand why it affects non-tracepoint events though. > > > > > > > > $ sudo ./perf test -v pipe > > > > --- start --- > > > > test child forked, pid 3036123 > > > > 1bde35-1bdecc l noploop > > > > perf does have symbol 'noploop' > > > > > > > > Record+report pipe test > > > > [ perf record: Woken up 1 times to write data ] > > > > [ perf record: Captured and wrote 0.210 MB - ] > > > > [ perf record: Woken up 2 times to write data ] > > > > [ perf record: Captured and wrote 0.517 MB - ] > > > > [ perf record: Woken up 2 times to write data ] > > > > [ perf record: Captured and wrote 0.516 MB - ] > > > > Record+report pipe test [Success] > > > > > > > > Inject -B build-ids test > > > > 0xa5c [0x17a4]: failed to process type: 80 > > > > Error: > > > > failed to process sample > > > > Inject build-ids test [Failed - cannot find noploop function in pipe #1] > > > > > > > > Inject -b build-ids test > > > > 0xa5c [0x17a4]: failed to process type: 80 > > > > Error: > > > > failed to process sample > > > > Inject build-ids test [Failed - cannot find noploop function in pipe #1] > > > > > > > > Inject --buildid-all build-ids test > > > > 0xa5c [0x17a4]: failed to process type: 80 > > > > Error: > > > > failed to process sample > > > > Inject build-ids test [Failed - cannot find noploop function in pipe #1] > > > > > > > > Inject --mmap2-buildid-all build-ids test > > > > 0xa5c [0x17a4]: failed to process type: 80 > > > > Error: > > > > failed to process sample > > > > Inject build-ids test [Failed - cannot find noploop function in pipe #1] > > > > ---- end(-1) ---- > > > > 84: perf pipe recording and injection test : FAILED! > > > > > > > > $ sudo ./perf test -v Zstd > > > > --- start --- > > > > test child forked, pid 3036097 > > > > Collecting compressed record file: > > > > 500+0 records in > > > > 500+0 records out > > > > 256000 bytes (256 kB, 250 KiB) copied, 0.00169127 s, 151 MB/s > > > > [ perf record: Woken up 1 times to write data ] > > > > [ perf record: Captured and wrote 0.032 MB /tmp/perf.data.KBo, compressed (original 0.004 MB, ratio is 3.324) ] > > > > Checking compressed events stats: > > > > Couldn't decompress data > > > > 0x7ca8 [0x4f2]: failed to process type: 81 [Operation not permitted] > > > > Error: > > > > failed to process sample > > > > ---- end(-1) ---- > > > > 86: Zstd perf.data compression/decompression : FAILED! > > > > > > > > Thanks, > > > > Namhyung > > > > > > I'm not able to reproduce: > > > ``` > > > $ git log --oneline |head > > > a59bca6eb0a6 perf test: Add a runs-per-test flag > > > 0d0c002eb45c perf tests: Enable tests disabled due to tracepoint parsing > > > 4b8f5c9dfbda perf evsel: Allow evsel__newtp without libtraceevent > > > 7f57057c7884 perf evsel: Add/use accessor for tp_format > > > c27d357d2d4c perf trace-event: Always build trace-event-info.c > > > 20bf7a2cd68a perf trace-event: Constify print arguments > > > f18b07ee2af1 tool api fs: Correctly encode errno for read/write open failures > > > ... > > > $ sudo /tmp/perf/perf test -r 10 Zstd pipe -v > > > 84: perf pipe recording and injection test : Ok > > > 84: perf pipe recording and injection test : Ok > > > 84: perf pipe recording and injection test : Ok > > > 84: perf pipe recording and injection test : Ok > > > 84: perf pipe recording and injection test : Ok > > > 84: perf pipe recording and injection test : Ok > > > 84: perf pipe recording and injection test : Ok > > > 84: perf pipe recording and injection test : Ok > > > 84: perf pipe recording and injection test : Ok > > > 84: perf pipe recording and injection test : Ok > > > 86: Zstd perf.data compression/decompression : Ok > > > 86: Zstd perf.data compression/decompression : Ok > > > 86: Zstd perf.data compression/decompression : Ok > > > 86: Zstd perf.data compression/decompression : Ok > > > 86: Zstd perf.data compression/decompression : Ok > > > 86: Zstd perf.data compression/decompression : Ok > > > 86: Zstd perf.data compression/decompression : Ok > > > 86: Zstd perf.data compression/decompression : Ok > > > 86: Zstd perf.data compression/decompression : Ok > > > 86: Zstd perf.data compression/decompression : Ok > > > ``` > > > Similarly not as root or if runs-per-test is 100. > > > > > > Agreed that the changes are for tracepoints and these tests aren't for > > > tracepoints, so an interaction wouldn't be expected. If you have a > > > reliable reproduction perhaps you can bisect it. > > > > it says: > > > > 9c10de391840a35ab095b65e9a5c4fad0ac52068 is the first bad commit > > commit 9c10de391840a35ab095b65e9a5c4fad0ac52068 (HEAD) > > Author: Ian Rogers <irogers@...gle.com> > > Date: Fri Nov 8 10:47:46 2024 -0800 > > > > tool api fs: Correctly encode errno for read/write open failures > > > > Switch from returning -1 to -errno so that callers can determine types > > of failure. > > > > Signed-off-by: Ian Rogers <irogers@...gle.com> > > Acked-by: Arnaldo Carvalho de Melo <acme@...hat.com> > > > > tools/lib/api/fs/fs.c | 6 +++--- > > 1 file changed, 3 insertions(+), 3 deletions(-) > > So I tried to eye-ball/grep all callers to spot assumptions on the > return value like: > ``` > err = ...__read_int > if (err == -1) > ``` > Didn't spot anything. > > It seems in the test log the record is failing so I ran this under > gdb, set breakpoints on the 3 modified functions and then looked up > the call stack to spot bad return value assumptions. Everything looks > good. > I then tried inject and report, the only file read by these functions > is /proc/sys/kernel/perf_event_paranoid as part of symbol > initialization (nit, this should probably be read lazily and the > restriction should really come from the perf.data file, not the > running system) and those calls look good. > > The change is small and not critical for the series. It improves the > error message when reading the tracepoint id fails. So we could move > forward with the rest of the series, but that could be annoying for > tracepoint users. > > If I had a reproducer I'd revert the 1 line change on each function to > find out which is causing the regression. Once you have that then you > can binary search to find the bad call by using some global counter > where the first 'n' calls use the new return value and the later use > the old value. You can then vary 'n' to binary search and find the bad > caller. > > Is there any chance you can help diagnose this or help me to find the > reproducer? I think this depends on the system configuration. I've debugged it failed when it gets cpu topology: ... read int failed: /sys/devices/system/cpu/cpu112/topology/core_id (errno=2) read int failed: /sys/devices/system/cpu/cpu112/topology/physical_package_id (errno=2) read int failed: /sys/devices/system/cpu/cpu112/topology/die_id (errno=2) ... Maybe it's because # online CPUs != # possible CPUs. $ cat /sys/devices/system/cpu/online 0-63 $ cat /sys/devices/system/cpu/possible 0-127 There's a code like cpu__get_socket_id() to use the return value of sysfs__read_int() directly. And it saves the value to aggr_cpu_id which requires exact match like in aggr_cpu_id__equal(). Thanks, Namhyung
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