linux-kernel - [tip: perf/core] arm_pmu: Add PERF_PMU_CAP_EXTENDED_HW

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Message-ID: <169079877184.28540.10430162346785754837.tip-bot2@tip-bot2>
Date:   Mon, 31 Jul 2023 10:19:31 -0000
From:   "tip-bot2 for James Clark" <tip-bot2@...utronix.de>
To:     linux-tip-commits@...r.kernel.org
Cc:     Ian Rogers <irogers@...gle.com>, James Clark <james.clark@....com>,
        "Peter Zijlstra (Intel)" <peterz@...radead.org>,
        Anshuman Khandual <anshuman.khandual@....com>, x86@...nel.org,
        linux-kernel@...r.kernel.org
Subject: [tip: perf/core] arm_pmu: Add PERF_PMU_CAP_EXTENDED_HW_TYPE capability

The following commit has been merged into the perf/core branch of tip:

Commit-ID:     5c816728651ae425954542fed64d21d40cb75a9f
Gitweb:        https://git.kernel.org/tip/5c816728651ae425954542fed64d21d40cb75a9f
Author:        James Clark <james.clark@....com>
AuthorDate:    Mon, 24 Jul 2023 14:44:56 +01:00
Committer:     Peter Zijlstra <peterz@...radead.org>
CommitterDate: Wed, 26 Jul 2023 12:28:46 +02:00

arm_pmu: Add PERF_PMU_CAP_EXTENDED_HW_TYPE capability

This capability gives us the ability to open PERF_TYPE_HARDWARE and
PERF_TYPE_HW_CACHE events on a specific PMU for free. All the
implementation is contained in the Perf core and tool code so no change
to the Arm PMU driver is needed.

The following basic use case now results in Perf opening the event on
all PMUs rather than picking only one in an unpredictable way:

  $ perf stat -e cycles -- taskset --cpu-list 0,1 stress -c 2

   Performance counter stats for 'taskset --cpu-list 0,1 stress -c 2':

         963279620      armv8_cortex_a57/cycles/                (99.19%)
         752745657      armv8_cortex_a53/cycles/                (94.80%)

Fixes: 55bcf6ef314a ("perf: Extend PERF_TYPE_HARDWARE and PERF_TYPE_HW_CACHE")
Suggested-by: Ian Rogers <irogers@...gle.com>
Signed-off-by: James Clark <james.clark@....com>
Signed-off-by: Peter Zijlstra (Intel) <peterz@...radead.org>
Reviewed-by: Anshuman Khandual <anshuman.khandual@....com>
Acked-by: Ian Rogers <irogers@...gle.com>
Link: https://lore.kernel.org/r/20230724134500.970496-2-james.clark@arm.com
---
 drivers/perf/arm_pmu.c | 7 ++++++-
 1 file changed, 6 insertions(+), 1 deletion(-)

diff --git a/drivers/perf/arm_pmu.c b/drivers/perf/arm_pmu.c
index f6ccb2c..2e79201 100644
--- a/drivers/perf/arm_pmu.c
+++ b/drivers/perf/arm_pmu.c
@@ -880,8 +880,13 @@ struct arm_pmu *armpmu_alloc(void)
 		 * configuration (e.g. big.LITTLE). This is not an uncore PMU,
 		 * and we have taken ctx sharing into account (e.g. with our
 		 * pmu::filter callback and pmu::event_init group validation).
+		 *
+		 * PERF_PMU_CAP_EXTENDED_HW_TYPE is required to open
+		 * PERF_TYPE_HARDWARE and PERF_TYPE_HW_CACHE events on a
+		 * specific PMU.
 		 */
-		.capabilities	= PERF_PMU_CAP_HETEROGENEOUS_CPUS | PERF_PMU_CAP_EXTENDED_REGS,
+		.capabilities	= PERF_PMU_CAP_HETEROGENEOUS_CPUS | PERF_PMU_CAP_EXTENDED_REGS |
+				  PERF_PMU_CAP_EXTENDED_HW_TYPE,
 	};
 
 	pmu->attr_groups[ARMPMU_ATTR_GROUP_COMMON] =