Messages in this thread | | | From | Ian Rogers <> | Date | Fri, 10 May 2024 13:41:55 -0700 | Subject | Re: [PATCH 2/2] perf pmu: Fix num_events calculation |
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On Thu, May 9, 2024 at 11:52 PM Justin He <Justin.He@arm.com> wrote: > > Hi, Ian > > > -----Original Message----- > > From: Ian Rogers <irogers@google.com> > > Sent: Friday, May 10, 2024 2:17 PM > > To: Justin He <Justin.He@arm.com> > > Cc: Peter Zijlstra <peterz@infradead.org>; Ingo Molnar <mingo@redhat.com>; > > Arnaldo Carvalho de Melo <acme@kernel.org>; Namhyung Kim > > <namhyung@kernel.org>; Mark Rutland <Mark.Rutland@arm.com>; Alexander > > Shishkin <alexander.shishkin@linux.intel.com>; Jiri Olsa <jolsa@kernel.org>; > > Adrian Hunter <adrian.hunter@intel.com>; Kan Liang > > <kan.liang@linux.intel.com>; James Clark <James.Clark@arm.com>; > > linux-perf-users@vger.kernel.org; linux-kernel@vger.kernel.org > > Subject: Re: [PATCH 2/2] perf pmu: Fix num_events calculation > > > > On Thu, May 9, 2024 at 7:47 PM Jia He <justin.he@arm.com> wrote: > > > > > > When pe is NULL in the function perf_pmu__new_alias(), the total > > > number of events is added to loaded_json_aliases. However, if > > > pmu->events_table is NULL and cpu_aliases_added is false, the > > > calculation for the events number in perf_pmu__num_events() is incorrect. > > > > > > Then cause the error report after "perf list": > > > Unexpected event > > smmuv3_pmcg_3f062/smmuv3_pmcg_3f062/transaction// > > > > > > Fix it by adding loaded_json_aliases in the calculation under the > > > mentioned conditions. > > > > > > Test it also with "perf bench internals pmu-scan" and there is no > > > regression. > > > > > > Fixes: e6ff1eed3584 ("perf pmu: Lazily add JSON events") > > > Signed-off-by: Jia He <justin.he@arm.com> > > > --- > > > tools/perf/util/pmu.c | 2 ++ > > > 1 file changed, 2 insertions(+) > > > > > > diff --git a/tools/perf/util/pmu.c b/tools/perf/util/pmu.c index > > > a1eef7b2e389..a53224e2ce7e 100644 > > > --- a/tools/perf/util/pmu.c > > > +++ b/tools/perf/util/pmu.c > > > @@ -1639,6 +1639,8 @@ size_t perf_pmu__num_events(struct perf_pmu > > *pmu) > > > nr += pmu->loaded_json_aliases; > > > else if (pmu->events_table) > > > nr += > > pmu_events_table__num_events(pmu->events_table, > > > pmu) - pmu->loaded_json_aliases; > > > + else > > > + nr += pmu->loaded_json_aliases; > > > > Thanks for working on this! The "struct pmu_event *pe" in new_alias is an entry > > from the json data, and "pmu->events_table" should NULL if there is no json > > data. I believe the code is assuming that these lines aren't necessary as it > > shouldn't be possible to load json data if the json events table doesn't exist for > > the PMU - if there is no json data then loaded_json_aliases should be 0 and no > > addition is necessary. I'm wondering why this case isn't true for you. > On my Armv8a N2 server, "pmu->events_table" is NULL because perf_pmu__find_events_table() > return NULL. > > I also noticed that pmu->loaded_json_aliases is *not* 0. The missing adding calculation will cause > perf_pmu__num_events() less than normal case and will trigger latter check failure in > perf_pmus__print_pmu_events__callback(). > At last, perf list will report many lines similar as: > Unexpected event smmuv3_pmcg_3f062/smmuv3_pmcg_3f062/transaction//
The issue is the sys events which currently are ARM only. Here is an lldb stack trace: ``` frame #6: 0x0000aaaaabc9b49c perf`__assert_fail(assertion="pmu->events_table", file="tools/perf/util/pmu.c", line=522, function="int perf_pmu__new_alias(struct perf_pmu *, const char *, const char *, const char *, FILE *, const struct pmu_event *)") frame #7: 0x0000aaaaab41e018 perf`perf_pmu__new_alias(pmu=0x00007377e7e09b40, name="hnf_brd_snoops_sent", desc="Counts number of multicast snoops sent (not including SF back invalidation)", val="eventid=9,type=5", val_fd=0x0000000000000000, pe=0x0000ffffffffde88) at pmu.c:522:3 frame #8: 0x0000aaaaab4175cc perf`pmu_add_sys_aliases_iter_fn(pe=0x0000ffffffffde88, table=0x0000aaaaac299bb0, vdata=0x00007377e7e09b40) at pmu.c:939:3 frame #9: 0x0000aaaaaaf6d000 perf`pmu_events_table__for_each_event_pmu(table=0x0000aaaaac299bb0, pmu=0x0000aaaaac299238, fn=(perf`pmu_add_sys_aliases_iter_fn at pmu.c:931), data=0x00007377e7e09b40) at pmu-events.c:5994:23 frame #10: 0x0000aaaaaaf6cd78 perf`pmu_events_table__for_each_event(table=0x0000aaaaac299bb0, pmu=0x0000000000000000, fn=(perf`pmu_add_sys_aliases_iter_fn at pmu.c:931), data=0x00007377e7e09b40) at pmu-events.c:6057:23 frame #11: 0x0000aaaaaaf6ec44 perf`pmu_for_each_sys_event(fn=(perf`pmu_add_sys_aliases_iter_fn at pmu.c:931), data=0x00007377e7e09b40) at pmu-events.c:6295:27 frame #12: 0x0000aaaaab41738c perf`pmu_add_sys_aliases(pmu=0x00007377e7e09b40) at pmu.c:955:2 frame #13: 0x0000aaaaab4179fc perf`perf_pmu__lookup(pmus=0x0000aaaaac500970, dirfd=34, name="arm_cmn_0") at pmu.c:1037:2 frame #14: 0x0000aaaaab4242d0 perf`perf_pmu__find2(dirfd=34, name="arm_cmn_0") at pmus.c:161:9 frame #15: 0x0000aaaaab421614 perf`pmu_read_sysfs(core_only=false) at pmus.c:209:3 frame #16: 0x0000aaaaab42278c perf`perf_pmus__scan_skip_duplicates(pmu=0x0000000000000000) at pmus.c:297:3 frame #17: 0x0000aaaaab422078 perf`perf_pmus__print_pmu_events(print_cb=0x0000ffffffffec68, print_state=0x0000ffffffffecd0) at pmus.c:462:16 frame #18: 0x0000aaaaab425d9c perf`print_events(print_cb=0x0000ffffffffec68, print_state=0x0000ffffffffecd0) at print-events.c:409:2 frame #19: 0x0000aaaaab093ef0 perf`cmd_list(argc=0, argv=0x0000fffffffff340) at builtin-list.c:592:3 frame #20: 0x0000aaaaaaf5b490 perf`run_builtin(p=0x0000aaaaac4e8220, argc=1, argv=0x0000fffffffff340) at perf.c:349:11 frame #21: 0x0000aaaaaaf5a3e0 perf`handle_internal_command(argc=1, argv=0x0000fffffffff340) at perf.c:402:8 frame #22: 0x0000aaaaaaf5b1a0 perf`run_argv(argcp=0x0000fffffffff1c8, argv=0x0000fffffffff1c0) at perf.c:446:2 frame #23: 0x0000aaaaaaf59f44 perf`main(argc=1, argv=0x0000fffffffff340) at perf.c:562:3 ```
As such the fix here is incomplete. There may be both sys json events (detected by PMU/id name) and CPU json events (detected by CPUID). I'm looking into a fix.
Thanks, Ian
> -- > Cheers, > Justin (Jia He)
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