From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org Received: from bombadil.infradead.org (bombadil.infradead.org [198.137.202.133]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.lore.kernel.org (Postfix) with ESMTPS id 5340FC61DC2 for ; Thu, 27 Aug 2026 14:27:28 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; q=dns/txt; c=relaxed/relaxed; d=lists.infradead.org; s=bombadil.20210309; h=Sender:List-Subscribe:List-Help :List-Post:List-Archive:List-Unsubscribe:List-Id:In-Reply-To:Content-Type: MIME-Version:References:Message-ID:Subject:Cc:To:From:Date:Reply-To: Content-Transfer-Encoding:Content-ID:Content-Description:Resent-Date: Resent-From:Resent-Sender:Resent-To:Resent-Cc:Resent-Message-ID:List-Owner; bh=/QGm/YFP6xrwih2aqZGPXYJOhN5wWJFLJDg/51WYw20=; b=5Du3W1gQI1MhQM5FlTZYTMlIby aUpqOGmwvOHbR4k5np2UtqR3CkctxDl7zpRZGpyo6p4vysrbvIigayEyef8QCv/HZOQtSRuTkHJy6 20KyAAofZ71I7017cZaIfrA5COZ/qEi3iEBzEQC71AsH8ne2Xz5k8t2zdZvdSMhG90dCyc5xDG4ZM g6da/N6jOJsqLKjB89TwUrgOI/jcmvfAPADHj/nQbco83D+ULlyRKMDTbcgPGVHGXishoRWZafM3a 73ylPSdEz0J1kAAt/bPBUSiMggL9VkgTzhBdJJ31LpCObsg9wcp9Ofx2a8yOvJcR5RCLtHfVIKQW0 /Eaq3WHw==; Received: from localhost ([::1] helo=bombadil.infradead.org) by bombadil.infradead.org with esmtp (Exim 4.99.1 #2 (Red Hat Linux)) id 1wzb4a-00000004AHl-3oVt; Thu, 27 Aug 2026 14:27:20 +0000 Received: from foss.arm.com ([217.140.110.172]) by bombadil.infradead.org with esmtp (Exim 4.99.1 #2 (Red Hat Linux)) id 1wzb4Y-00000004AHR-0H6q for linux-arm-kernel@lists.infradead.org; Thu, 27 Aug 2026 14:27:19 +0000 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> 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> X-CRM114-Version: 20100106-BlameMichelson ( TRE 0.9.0 (BSD) ) MR-646709E3 X-CRM114-CacheID: sfid-20260827_072718_148399_82909120 X-CRM114-Status: GOOD ( 14.45 ) X-BeenThere: linux-arm-kernel@lists.infradead.org X-Mailman-Version: 2.1.34 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Sender: "linux-arm-kernel" Errors-To: linux-arm-kernel-bounces+linux-arm-kernel=archiver.kernel.org@lists.infradead.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