Messages in this thread Patch in this message | | | From | Stephane Eranian <> | Date | Mon, 14 Mar 2022 19:01:49 -0700 | Subject | Re: [PATCH v6 10/12] perf tools: Improve IBS error handling |
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Hi Kim,
On Tue, Feb 8, 2022 at 1:17 PM Stephane Eranian <eranian@google.com> wrote: > > From: Kim Phillips <kim.phillips@amd.com> > > improve the error message returned on failed perf_event_open() on AMD when > using IBS. > > Output of executing 'perf record -e ibs_op// true' BEFORE this patch: > > The sys_perf_event_open() syscall returned with 22 (Invalid argument)for event (ibs_op//u). > /bin/dmesg | grep -i perf may provide additional information. > > Output after: > > AMD IBS cannot exclude kernel events. Try running at a higher privilege level. > > Output of executing 'sudo perf record -e ibs_op// true' BEFORE this patch: > > Error: > The sys_perf_event_open() syscall returned with 22 (Invalid argument) for event (ibs_op//). > /bin/dmesg | grep -i perf may provide additional information. > > Output after: > > Error: > AMD IBS may only be available in system-wide/per-cpu mode. Try using -a, or -C and workload affinity > > Signed-off-by: Kim Phillips <kim.phillips@amd.com> > Cc: Arnaldo Carvalho de Melo <acme@redhat.com> > Cc: Alexander Shishkin <alexander.shishkin@linux.intel.com> > Cc: Boris Ostrovsky <boris.ostrovsky@oracle.com> > Cc: Ian Rogers <irogers@google.com> > Cc: Ingo Molnar <mingo@redhat.com> > Cc: Jiri Olsa <jolsa@redhat.com> > Cc: Joao Martins <joao.m.martins@oracle.com> > Cc: Konrad Rzeszutek Wilk <konrad.wilk@oracle.com> > Cc: Mark Rutland <mark.rutland@arm.com> > Cc: Michael Petlan <mpetlan@redhat.com> > Cc: Namhyung Kim <namhyung@kernel.org> > Cc: Peter Zijlstra <peterz@infradead.org> > Cc: Robert Richter <robert.richter@amd.com> > Cc: Stephane Eranian <eranian@google.com> > --- > tools/perf/util/evsel.c | 24 ++++++++++++++++++++++++ > 1 file changed, 24 insertions(+) > > diff --git a/tools/perf/util/evsel.c b/tools/perf/util/evsel.c > index 22d3267ce294..d42f63a484df 100644 > --- a/tools/perf/util/evsel.c > +++ b/tools/perf/util/evsel.c > @@ -2847,9 +2847,22 @@ static bool find_process(const char *name) > return ret ? false : true; > } > > +static bool is_amd(const char *arch, const char *cpuid) > +{ > + return arch && !strcmp("x86", arch) && cpuid && strstarts(cpuid, "AuthenticAMD"); > +} > + > +static bool is_amd_ibs(struct evsel *evsel) > +{ > + return evsel->core.attr.precise_ip || !strncmp(evsel->pmu_name, "ibs", 3); > +} > + > int evsel__open_strerror(struct evsel *evsel, struct target *target, > int err, char *msg, size_t size) > { > + struct perf_env *env = evsel__env(evsel); > + const char *arch = perf_env__arch(env); > + const char *cpuid = perf_env__cpuid(env);
This code dies for me on the latest tip.git because env = NULL and perf_env_cpuid() is broken for NULL argument. I don't quite know where this env global variable is set but I hope there is a better way of doing this, maybe using the evsel__env() function in the same util/evsel.c file.
Similarly, the is_amd_ibs() suffers from a NULL pointer dereference because evsel->pmu_name maybe NULL:
$ perf record -e rc2 .....
causes a NULL pmu_name.
Could you please send me an updated version to integrate with the branch sampling code?
Thanks.
> > char sbuf[STRERR_BUFSIZE]; > int printed = 0, enforced = 0; > > @@ -2949,6 +2962,17 @@ int evsel__open_strerror(struct evsel *evsel, struct target *target, > return scnprintf(msg, size, > "Invalid event (%s) in per-thread mode, enable system wide with '-a'.", > evsel__name(evsel)); > + if (is_amd(arch, cpuid)) { > + if (is_amd_ibs(evsel)) { > + if (evsel->core.attr.exclude_kernel) > + return scnprintf(msg, size, > + "AMD IBS can't exclude kernel events. Try running at a higher privilege level."); > + if (!evsel->core.system_wide) > + return scnprintf(msg, size, > + "AMD IBS may only be available in system-wide/per-cpu mode. Try using -a, or -C and workload affinity"); > + } > + } > + > break; > case ENODATA: > return scnprintf(msg, size, "Cannot collect data source with the load latency event alone. " > -- > 2.35.0.263.gb82422642f-goog >
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