From: Stephane Eranian <eranian@google.com>
To: linux-kernel@vger.kernel.org
Cc: peterz@infradead.org, kim.phillips@amd.com, acme@redhat.com,
jolsa@redhat.com, songliubraving@fb.com, mpe@ellerman.id.au,
maddy@linux.ibm.com
Subject: [PATCH v2 12/13] perf tools: improve error handling of AMD Branch Sampling
Date: Thu, 11 Nov 2021 00:44:14 -0800 [thread overview]
Message-ID: <20211111084415.663951-13-eranian@google.com> (raw)
In-Reply-To: <20211111084415.663951-1-eranian@google.com>
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>
---
tools/perf/util/evsel.c | 8 ++++++++
1 file changed, 8 insertions(+)
diff --git a/tools/perf/util/evsel.c b/tools/perf/util/evsel.c
index 1b24b3000d66..11aa6c28a9e4 100644
--- a/tools/perf/util/evsel.c
+++ b/tools/perf/util/evsel.c
@@ -2883,6 +2883,14 @@ int evsel__open_strerror(struct evsel *evsel, struct target *target,
return scnprintf(msg, size, "The 'aux_output' feature is not supported, update the kernel.");
if (is_amd && (evsel->core.attr.precise_ip || !strncmp(evsel->pmu_name, "ibs", 3)) && (evsel->core.attr.exclude_kernel))
return scnprintf(msg, size, "AMD IBS can't exclude kernel events. Try running at a higher privilege level.");
+
+ if (is_amd && ((evsel->core.attr.config & 0xff) == 0xc4) && (evsel->core.attr.sample_type & PERF_SAMPLE_BRANCH_STACK)) {
+ 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;
case ENODATA:
return scnprintf(msg, size, "Cannot collect data source with the load latency event alone. "
--
2.34.0.rc0.344.g81b53c2807-goog
next prev parent reply other threads:[~2021-11-11 8:52 UTC|newest]
Thread overview: 28+ messages / expand[flat|nested] mbox.gz Atom feed top
2021-11-11 8:44 [PATCH v2 00/13] perf/x86/amd: Add AMD Fam19h Branch Sampling support Stephane Eranian
2021-11-11 8:44 ` [PATCH v2 01/13] perf/core: add perf_clear_branch_entry_bitfields() helper Stephane Eranian
2021-11-11 8:44 ` [PATCH v2 02/13] x86/cpufeatures: add AMD Fam19h Branch Sampling feature Stephane Eranian
2021-11-11 12:36 ` Borislav Petkov
2021-11-11 8:44 ` [PATCH v2 03/13] perf/x86/amd: add AMD Fam19h Branch Sampling support Stephane Eranian
2021-11-12 16:02 ` Peter Zijlstra
2021-11-16 7:48 ` Stephane Eranian
2021-11-16 8:29 ` Peter Zijlstra
2021-11-17 7:23 ` Stephane Eranian
2021-11-18 12:20 ` Peter Zijlstra
2021-11-18 12:32 ` Peter Zijlstra
2021-11-29 22:07 ` Stephane Eranian
2021-11-12 16:23 ` Peter Zijlstra
2021-11-12 16:25 ` Peter Zijlstra
2021-11-12 16:39 ` Peter Zijlstra
2021-11-11 8:44 ` [PATCH v2 04/13] perf/x86/amd: add branch-brs helper event for Fam19h BRS Stephane Eranian
2021-11-11 8:44 ` [PATCH v2 05/13] perf/x86/amd: enable branch sampling priv level filtering Stephane Eranian
2021-11-11 8:44 ` [PATCH v2 06/13] perf/x86/amd: add AMD branch sampling period adjustment Stephane Eranian
2021-11-11 8:44 ` [PATCH v2 07/13] perf/x86/amd: make Zen3 branch sampling opt-in Stephane Eranian
2021-11-11 8:44 ` [PATCH 08/13] ACPI: add perf low power callback Stephane Eranian
2021-11-11 8:44 ` [PATCH v2 09/13] perf/x86/amd: add idle hooks for branch sampling Stephane Eranian
2021-11-11 8:44 ` [PATCH v2 10/13] perf tools: add branch-brs as a new event Stephane Eranian
2021-11-11 8:44 ` [PATCH v2 11/13] perf tools: improve IBS error handling Stephane Eranian
2021-11-16 16:46 ` Kim Phillips
2021-11-17 9:15 ` Stephane Eranian
2021-11-18 21:02 ` Kim Phillips
2021-11-11 8:44 ` Stephane Eranian [this message]
2021-11-11 8:44 ` [PATCH v2 13/13] perf report: add addr_from/addr_to sort dimensions Stephane Eranian
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