Messages in this thread Patch in this message | | | Subject | Re: [PATCH 2/2] perf tools: Improve IBS error handling | From | kajoljain <> | Date | Tue, 23 Nov 2021 14:10:53 +0530 |
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On 10/8/21 12:47 AM, Kim Phillips wrote: > On 10/7/21 12:28 PM, Jiri Olsa wrote: >> On Mon, Oct 04, 2021 at 04:41:14PM -0500, Kim Phillips wrote: >>> --- >>> 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 b915840690d4..f8a9cbd99314 100644 >>> --- a/tools/perf/util/evsel.c >>> +++ b/tools/perf/util/evsel.c >>> @@ -2743,9 +2743,22 @@ 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); >>> char sbuf[STRERR_BUFSIZE]; >>> int printed = 0, enforced = 0; >>> @@ -2841,6 +2854,17 @@ int evsel__open_strerror(struct evsel >>> *evsel, struct target *target, >>> return scnprintf(msg, size, "wrong clockid (%d).", >>> clockid); >>> if (perf_missing_features.aux_output) >>> return scnprintf(msg, size, "The 'aux_output' feature >>> is not supported, update the kernel."); >>> + if (is_amd(arch, cpuid)) { >>> + if (is_amd_ibs(evsel)) { >> >> would single 'is_amd_ibs' call be better? checking on both amd and ibs > > Good suggestion. If you look at the later patch in the > BRS series, I have rewritten it to add the new > AMD PMU like so: > > if (is_amd()) { > if (is_amd_ibs()) { > if (evsel->this) > return > if (evsel->that) > return > } > + if (is_amd_brs()) { > + if (evsel->this) > + return > + if (evsel->that) > + return > + } > }
Hi Kim, From my point of view, it won't be a good idea of adding so many checks in common function definition itself.
Can you just create a check to see if its amd machine and then add a function call which will handle all four conditions together?
which is basically for:
+ 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"); + }
and this:
+ if (is_amd_brs(evsel)) { + if (evsel->core.attr.freq) + return scnprintf(msg, size, + "AMD Branch Sampling does not support frequency mode sampling, must pass a fixed sampling period via -c option or cpu/branch-brs,period=xxxx/."); + /* another reason is that the period is too small */ + return scnprintf(msg, size, + "AMD Branch Sampling does not support sampling period smaller than what is reported in /sys/devices/cpu/caps/branches."); + }
So, incase we are in amd machine, common function evsel__open_strerror will call function may be something like amd_evesel_open_strerror_check which will look for both ibs and brs conditions and return corresponding error statement.
Thanks, Kajol Jain
> > Below is the full proposed replacement patch for patch 12 > of 13 of the BRS series. > > Another option is to have the is_amd_{ibs,brs} functions > call is_amd() themselves, so the if (evsel->) code could be > unindented by one tab, would that be better? > > Thanks, > > Kim > > From a4cbab762719b30bddec2e278cf8b8eb82e83865 Mon Sep 17 00:00:00 2001 > From: Stephane Eranian <eranian@google.com> > Date: Thu, 9 Sep 2021 00:56:59 -0700 > Subject: [PATCH] perf tools: Improve error handling of AMD Branch Sampling > > This patch improves the error message printed by perf when > perf_event_open() fails on AMD Zen3 when using the branch sampling > feature. In the case of EINVAL, there are two main reasons: frequency > mode or period is smaller than the depth of the branch sampling > buffer (16). The patch checks the parameters of the call and tries > to print a relevant message to explain the error: > > $ perf record -b -e cpu/branch-brs/ -c 10 ls > Error: > AMD Branch Sampling does not support sampling period smaller than what > is reported in /sys/devices/cpu/caps/branches. > > $ perf record -b -e cpu/branch-brs/ ls > Error: > AMD Branch Sampling does not support frequency mode sampling, must pass > a fixed sampling period via -c option or cpu/branch-brs,period=xxxx/. > > Signed-off-by: Stephane Eranian <eranian@google.com> > [Rebased on commit 9fe8895a27a84 ("perf env: Add perf_env__cpuid, > perf_env__{nr_}pmu_mappings")] > Signed-off-by: Kim Phillips <kim.phillips@amd.com> > --- > tools/perf/util/evsel.c | 14 ++++++++++++++ > 1 file changed, 14 insertions(+) > > diff --git a/tools/perf/util/evsel.c b/tools/perf/util/evsel.c > index f8a9cbd99314..e1f5eff07355 100644 > --- a/tools/perf/util/evsel.c > +++ b/tools/perf/util/evsel.c > @@ -2753,6 +2753,12 @@ static bool is_amd_ibs(struct evsel *evsel) > return evsel->core.attr.precise_ip || !strncmp(evsel->pmu_name, > "ibs", 3); > } > > +static bool is_amd_brs(struct evsel *evsel) > +{ > + return ((evsel->core.attr.config & 0xff) == 0xc4) && > + (evsel->core.attr.sample_type & PERF_SAMPLE_BRANCH_STACK); > +} > + > int evsel__open_strerror(struct evsel *evsel, struct target *target, > int err, char *msg, size_t size) > { > @@ -2863,6 +2869,14 @@ int evsel__open_strerror(struct evsel *evsel, > struct target *target, > return scnprintf(msg, size, > "AMD IBS may only be available in system-wide/per-cpu mode. Try > using -a, or -C and workload affinity"); > } > + if (is_amd_brs(evsel)) { > + if (evsel->core.attr.freq) > + return scnprintf(msg, size, > + "AMD Branch Sampling does not support frequency mode sampling, must > pass a fixed sampling period via -c option or > cpu/branch-brs,period=xxxx/."); > + /* another reason is that the period is too small */ > + return scnprintf(msg, size, > + "AMD Branch Sampling does not support sampling period smaller than > what is reported in /sys/devices/cpu/caps/branches."); > + } > } > > break;
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