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 609DC47A0D7; Thu, 27 Aug 2026 14:27:17 +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=1787840842; cv=none; b=iuyZW3n4jbQ40uL4DOorwIcmwhS1iInqTtZ8N1m2XuqpE57LZ4NKRDWHR0DBGP0/j7ifY+c2AFc+ZpK4ea2K8zgdDoPV+LrRvXHK5HekExf/05fA2oPK0tqbVbL8njst6RmtyF86pzmT/ai4TqFu9ol66lgf42jHZnzrehxpI1g= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1787840842; c=relaxed/simple; bh=r0ySLqPyuNENyTpsvEaGFphpnJIcH3tX6bc1QHr9jqg=; h=Date:From:To:Cc:Subject:Message-ID:References:MIME-Version: Content-Type:Content-Disposition:In-Reply-To; b=exfOroNXRZSQ1hEH3stUTk3tscAfJvZVMYNjfW25VfplgksqapX+spZW91o+T00LI4BzM1R4uA04zczAvRPPeXfKHQlsSP87dAZsXirpo48pGJpQRglZSn54E5jqFJv/tHHinq1TVat+FNg7vEZ2Dolc2Wmk3ESW8GJAHVsHKQo= 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; dkim=pass (1024-bit key) header.d=arm.com header.i=@arm.com header.b=IeV45dqg; 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 Authentication-Results: smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=arm.com header.i=@arm.com header.b="IeV45dqg" 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 77BF71691; Thu, 27 Aug 2026 07:27:12 -0700 (PDT) Received: from localhost (unknown [10.2.196.114]) by usa-sjc-imap-foss1.foss.arm.com (Postfix) with ESMTPSA id F32CB3F7D8; Thu, 27 Aug 2026 07:27:15 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=simple/simple; d=arm.com; s=foss; t=1787840836; bh=r0ySLqPyuNENyTpsvEaGFphpnJIcH3tX6bc1QHr9jqg=; h=Date:From:To:Cc:Subject:References:In-Reply-To:From; b=IeV45dqgx4mRaxoEbmuZZLi7m359mdGCaHjEZzT8ye+3dWAGoS8D9re32lynaa88z JeSfSWhc2s3EO8J3VgE/iJvR6Od4/WQWFvSAn5IM61hKHm5org2eLQ1hd31ZLY6VFx qy4wuTAMTjSNYGKKfU4BMKZpRvEeF5DPdPO/fCsU= Date: Thu, 27 Aug 2026 15:27:14 +0100 From: Leo Yan To: James Clark Cc: Suzuki K Poulose , Mike Leach , John Garry , Will Deacon , Peter Zijlstra , Ingo Molnar , Arnaldo Carvalho de Melo , Namhyung Kim , Mark Rutland , Alexander Shishkin , Jiri Olsa , Ian Rogers , Adrian Hunter , Mathieu Poirier , Jonathan Corbet , Shuah Khan , Suyash Mahar , Amir Ayupov , Leo Yan , linux-arm-kernel@lists.infradead.org, coresight@lists.linaro.org, linux-perf-users@vger.kernel.org, linux-kernel@vger.kernel.org, Arnaldo Carvalho de Melo , linux-doc@vger.kernel.org Subject: Re: [PATCH v2 05/14] perf cs-etm: Increase default timestamp generation period Message-ID: <20260827142714.GM8904@e132581.arm.com> References: <20260821-james-cs-unformatted-per-thread-fix-v2-0-00c4fd0701b4@linaro.org> <20260821-james-cs-unformatted-per-thread-fix-v2-5-00c4fd0701b4@linaro.org> 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: <20260821-james-cs-unformatted-per-thread-fix-v2-5-00c4fd0701b4@linaro.org> On Fri, Aug 21, 2026 at 10:49:03AM +0100, James Clark wrote: > The original purpose of timestamps in per-CPU mode was to roughly emit > samples in the order they occurred across multiple CPUs, rather than > emit all the trace from CPU 1 followed by all from CPU 2 etc. > Previously there was no way to change the interval from the minimum of 1 > cycle, but custom intervals are now supported by the driver. > > Drastically reduce the number of timestamps emitted by increasing the > interval, which is more than enough to interleave sample generation. > This reduces the size of the trace generated. > > Signed-off-by: James Clark Reviewed-by: Leo Yan