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Sender: Namhyung Kim <namhyung@gmail.com>
From:   Namhyung Kim <namhyung@kernel.org>
To:     Peter Zijlstra <peterz@infradead.org>,
        Ingo Molnar <mingo@kernel.org>
Cc:     Mark Rutland <mark.rutland@arm.com>,
        Alexander Shishkin <alexander.shishkin@linux.intel.com>,
        Arnaldo Carvalho de Melo <acme@kernel.org>,
        LKML <linux-kernel@vger.kernel.org>,
        Ian Rogers <irogers@google.com>,
        Kan Liang <kan.liang@linux.intel.com>,
        Mingwei Zhang <mizhang@google.com>
Subject: [PATCH 3/3] perf/x86: Add CAP_NO_INTERRUPT for uncore PMUs
Date:   Mon, 20 Nov 2023 14:19:32 -0800
Message-ID: <20231120221932.213710-3-namhyung@kernel.org>
In-Reply-To: <20231120221932.213710-1-namhyung@kernel.org>
References: <20231120221932.213710-1-namhyung@kernel.org>
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It doesn't support sampling in uncore PMU events.  While it's
technically possible to generate interrupts, let's treat it as if it
has no interrupt in order to skip the freq adjust/unthrottling logic
in the timer handler which is only meaningful to sampling events.

Also remove the sampling event check because it'd be done in the general
code in the perf_event_open syscall.

Signed-off-by: Namhyung Kim <namhyung@kernel.org>
---
 arch/x86/events/intel/uncore.c | 11 ++++++-----
 1 file changed, 6 insertions(+), 5 deletions(-)

diff --git a/arch/x86/events/intel/uncore.c b/arch/x86/events/intel/uncore.c
index 69043e02e8a7..f7e6228bd1b1 100644
--- a/arch/x86/events/intel/uncore.c
+++ b/arch/x86/events/intel/uncore.c
@@ -744,10 +744,6 @@ static int uncore_pmu_event_init(struct perf_event *event)
 	if (pmu->func_id < 0)
 		return -ENOENT;
 
-	/* Sampling not supported yet */
-	if (hwc->sample_period)
-		return -EINVAL;
-
 	/*
 	 * Place all uncore events for a particular physical package
 	 * onto a single cpu
@@ -919,7 +915,12 @@ static int uncore_pmu_register(struct intel_uncore_pmu *pmu)
 			.stop		= uncore_pmu_event_stop,
 			.read		= uncore_pmu_event_read,
 			.module		= THIS_MODULE,
-			.capabilities	= PERF_PMU_CAP_NO_EXCLUDE,
+			/*
+			 * It doesn't allow sampling for uncore events, let's
+			 * treat the PMU has no interrupts to skip them in the
+			 * perf_adjust_freq_unthr_context().
+			 */
+			.capabilities	= PERF_PMU_CAP_NO_EXCLUDE | PERF_PMU_CAP_NO_INTERRUPT,
 			.attr_update	= pmu->type->attr_update,
 		};
 	} else {
-- 
2.43.0.rc1.413.gea7ed67945-goog