From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from foss.arm.com (foss.arm.com [217.140.110.172]) by smtp.subspace.kernel.org (Postfix) with ESMTP id 6B1BA4B1E4A; Fri, 16 May 2025 13:24:24 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=217.140.110.172 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1747401866; cv=none; b=W/Wh4WpPHbQHiuwQVn9/o+h2XCrp/sP1akWzkBHkoYfrKN/6tqXqAP/xcslYzTNGi7Q08uIHLffn8nHUxF7LtdoRrmZm37OM7G+D10SG60IlXYmceIUVVjmDH3K7K0HkBUscdpYXOYHQwrSkyLOP0iNGR7tXgdsrkbZXfyxXWqw= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1747401866; c=relaxed/simple; bh=6/jcxTEdm9wXe+6OlFOP2LEwhHepytwKIl2c/ZL4CKQ=; h=Date:From:To:Cc:Subject:Message-ID:References:MIME-Version: Content-Type:Content-Disposition:In-Reply-To; b=BXbAcE7olPKVtBC56TneHZMx6Lgvjpc3qsQKmOh/QL3F9atT9KX4AAYUmqiedZ5FOvjYfXT9fhDf9cTsbr80vgV+nSHhUhbpEplkL1x7gqZYeax353+xezyPrjTUReAI6FeMjJ9rwpThLxJR+nvmHL6s4ivizaaR8TZOpjsI84A= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=arm.com; spf=pass smtp.mailfrom=arm.com; arc=none smtp.client-ip=217.140.110.172 Authentication-Results: smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=arm.com Authentication-Results: smtp.subspace.kernel.org; spf=pass smtp.mailfrom=arm.com Received: from usa-sjc-imap-foss1.foss.arm.com (unknown [10.121.207.14]) by usa-sjc-mx-foss1.foss.arm.com (Postfix) with ESMTP id BD6E6169C; Fri, 16 May 2025 06:24:05 -0700 (PDT) Received: from localhost (e132581.arm.com [10.1.196.87]) by usa-sjc-imap-foss1.foss.arm.com (Postfix) with ESMTPSA id 4CCC83F673; Fri, 16 May 2025 06:24:17 -0700 (PDT) Date: Fri, 16 May 2025 14:24:12 +0100 From: Leo Yan To: kan.liang@linux.intel.com Cc: peterz@infradead.org, mingo@redhat.com, namhyung@kernel.org, irogers@google.com, mark.rutland@arm.com, linux-kernel@vger.kernel.org, linux-perf-users@vger.kernel.org, eranian@google.com, ctshao@google.com, tmricht@linux.ibm.com, Rob Herring , Vincenzo Frascino , Will Deacon Subject: Re: [PATCH V2 07/15] perf/arm: Remove driver-specific throttle support Message-ID: <20250516132412.GF412060@e132581.arm.com> References: <20250514151401.2547932-1-kan.liang@linux.intel.com> <20250514151401.2547932-8-kan.liang@linux.intel.com> Precedence: bulk X-Mailing-List: linux-perf-users@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20250514151401.2547932-8-kan.liang@linux.intel.com> On Wed, May 14, 2025 at 08:13:53AM -0700, kan.liang@linux.intel.com wrote: > From: Kan Liang > > The throttle support has been added in the generic code. Remove > the driver-specific throttle support. > > Besides the throttle, perf_event_overflow may return true because of > event_limit. It already does an inatomic event disable. The pmu->stop > is not required either. > > Signed-off-by: Kan Liang > Cc: Mark Rutland > Cc: Rob Herring (Arm) > Cc: Vincenzo Frascino > Cc: Will Deacon > --- > drivers/perf/arm_pmuv3.c | 3 +-- > drivers/perf/arm_v6_pmu.c | 3 +-- > drivers/perf/arm_v7_pmu.c | 3 +-- > drivers/perf/arm_xscale_pmu.c | 6 ++---- > 4 files changed, 5 insertions(+), 10 deletions(-) > > diff --git a/drivers/perf/arm_pmuv3.c b/drivers/perf/arm_pmuv3.c > index e506d59654e7..3db9f4ed17e8 100644 > --- a/drivers/perf/arm_pmuv3.c > +++ b/drivers/perf/arm_pmuv3.c > @@ -887,8 +887,7 @@ static irqreturn_t armv8pmu_handle_irq(struct arm_pmu *cpu_pmu) > * an irq_work which will be taken care of in the handling of > * IPI_IRQ_WORK. > */ > - if (perf_event_overflow(event, &data, regs)) > - cpu_pmu->disable(event); > + perf_event_overflow(event, &data, regs); I did a test for Arm PMUv3, sometimes I can get consistent result crossing events, but I still saw discrepancy in some runs: # perf record -c 400 -C 4,5,6,7 -e "{cycles,cycles}:S" -- sleep 5 # perf report -D | grep PERF_RECORD_SAMPLE -a4 | tail -n 5 7 5691046123610 0x63670 [0x68]: PERF_RECORD_SAMPLE(IP, 0x1): 0/0: 0xffff80008137a6d0 period: 400 addr: 0 ... sample_read: .... group nr 2 ..... id 00000000000000bf, value 000000000019d7a7, lost 0 ..... id 00000000000000c3, value 000000000019d3f9, lost 0 Though it does not dismiss discrepancy totally (maybe it depends on hardware mechanism), I do see this series can mitigate the issue significantly. Tested-by: Leo Yan