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 486D1C282DE for ; Mon, 10 Mar 2025 16:21:02 +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=EMOQxSEFmHXdVNrsaGEIU2oM02xZa9rLXAPz5X9hq+Q=; b=RjjCbm3i3pM7rhFcWE2Bdtaaxu MBf7zvmteA/Spn+4T3JDRxJXBVNIVr6DBv8iKiiNkFXbzMGW6WIgKKe5ddQ0BFYNY+Apw5XJkIwvv Tv02Uj3RSE7JekEFMQ5djPuB4Yi3NJ8gqItlBzCixzxc7FnJZ8HWuGsYWsgAsX1Z6JCeuBt6qq7Hj bf91lYUHREUJry5D5l4e6urCufLk7ELndshcCxTeMTIJSHsh0DnQgnPYlld3fRMv4/LsvPgRKWLKE BsSC0dGTHTUS/OlGXdbcfdnX6nTgupAR3DwseiFcfALTW6oHaW3jNt/wCSmzzq5JepPh1b+z7l8TL tQapI6oQ==; Received: from localhost ([::1] helo=bombadil.infradead.org) by bombadil.infradead.org with esmtp (Exim 4.98 #2 (Red Hat Linux)) id 1trfs1-00000003L0o-3Yhg; Mon, 10 Mar 2025 16:20:49 +0000 Received: from foss.arm.com ([217.140.110.172]) by bombadil.infradead.org with esmtp (Exim 4.98 #2 (Red Hat Linux)) id 1trfOX-00000003Ha4-07Wn for linux-arm-kernel@lists.infradead.org; Mon, 10 Mar 2025 15:50:22 +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 6EF4E1692; Mon, 10 Mar 2025 08:50:31 -0700 (PDT) Received: from localhost (e132581.arm.com [10.1.196.87]) by usa-sjc-imap-foss1.foss.arm.com (Postfix) with ESMTPSA id 96B003F5A1; Mon, 10 Mar 2025 08:50:19 -0700 (PDT) Date: Mon, 10 Mar 2025 15:50:15 +0000 From: Leo Yan To: Suzuki K Poulose Cc: Mike Leach , James Clark , Jonathan Corbet , Alexander Shishkin , Arnaldo Carvalho de Melo , Namhyung Kim , coresight@lists.linaro.org, linux-arm-kernel@lists.infradead.org, linux-doc@vger.kernel.org, linux-kernel@vger.kernel.org Subject: Re: [PATCH v2 5/8] coresight: etm: Add an attribute for updating buffer Message-ID: <20250310155015.GG9682@e132581.arm.com> References: <20250310104919.58816-1-leo.yan@arm.com> <20250310104919.58816-6-leo.yan@arm.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: X-CRM114-Version: 20100106-BlameMichelson ( TRE 0.8.0 (BSD) ) MR-646709E3 X-CRM114-CacheID: sfid-20250310_085021_118419_516E7348 X-CRM114-Status: GOOD ( 16.19 ) 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 Mon, Mar 10, 2025 at 01:29:26PM +0000, Suzuki Kuruppassery Poulose wrote: > Hi Leo > > On 10/03/2025 10:49, Leo Yan wrote: > > Add an attribute for updating buffer when the AUX trace is paused. And > > populate the value to the 'update_buf_on_pause' flag during the AUX > > setting up. > > Do we need this attribute in the uAPI ? This uAPI allows users to perform AUX pause and resume without the long latency caused by copying hardware trace data. E.g., a user can specify a large AUX buffer size using option "-m,128M". If the buffer is considered large enough to accommodate hardware trace data for a small program, the 'update_buf_on_pause' flag can be set to false, the copying will be deferred until the end of the perf session. I am bias to keep this uAPI. If you prefer to remove it, I am also fine with that. > Could we do this by default for > sinks without interrupt ? This definitely improves the quality of trace > collected for such sinks and the driver can transparently do this. How about we dynamically set the default flag in the Perf tool? - If users set explictly the 'update_buf_on_pause' flag, then the setting will be respected. - If users don't set the flag, perf tool detects it is TRBE sinks, then it can set 'update_buf_on_pause' flag as false. - If users don't set the flag, perf tool detects it is ETF/ETB/ETR sinks, it sets the flag as true. Thanks, Leo