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 3B064C282DE for ; Mon, 10 Mar 2025 18:05:19 +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=j3VoGHU+aZOv6VXL7a9Oy3oa0s55DgEU9jDiAaVbfmg=; b=QKIqlacZdEv5nN8mp2dfUHXAUl K1Y+634os/2x0f+0ai514MnUPY9ES+84KzwbCls/TQXSi2cyHRKCl7fqaFne2km/4Sn1CmZF/60md UFx3KkbCIWQiINnOYqwsek8DfhE81qkDV503wgM3Tql8qH5iNFipLGuugUZsHV4xDqJSnSklfNbll VGdME4l+cmcjc1Xzp9f3sAgqAT7SIMfxB3h0+4bZ6XpNuzS/wgn8p6+slA9SuiXMVP8nB6GyYmJK3 2qOb9RwITjPmmAWBHZ0nNnIodam5sChW3zAKt4k4r0GQRrg9K+6SaDjUGPO195iFPznTBPpuXtU1I T2hfbpnQ==; Received: from localhost ([::1] helo=bombadil.infradead.org) by bombadil.infradead.org with esmtp (Exim 4.98 #2 (Red Hat Linux)) id 1trhUx-00000003Ylw-476z; Mon, 10 Mar 2025 18:05:07 +0000 Received: from foss.arm.com ([217.140.110.172]) by bombadil.infradead.org with esmtp (Exim 4.98 #2 (Red Hat Linux)) id 1trhTL-00000003Yd7-0QDW for linux-arm-kernel@lists.infradead.org; Mon, 10 Mar 2025 18:03:28 +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 68C191516; Mon, 10 Mar 2025 11:03:34 -0700 (PDT) Received: from localhost (e132581.arm.com [10.1.196.87]) by usa-sjc-imap-foss1.foss.arm.com (Postfix) with ESMTPSA id 98BA53F673; Mon, 10 Mar 2025 11:03:22 -0700 (PDT) Date: Mon, 10 Mar 2025 18:03:18 +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: <20250310180318.GH9682@e132581.arm.com> References: <20250310104919.58816-1-leo.yan@arm.com> <20250310104919.58816-6-leo.yan@arm.com> <20250310155015.GG9682@e132581.arm.com> <3f4354e7-e74b-4ce9-b0c7-4be103cbc94d@arm.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <3f4354e7-e74b-4ce9-b0c7-4be103cbc94d@arm.com> X-CRM114-Version: 20100106-BlameMichelson ( TRE 0.8.0 (BSD) ) MR-646709E3 X-CRM114-CacheID: sfid-20250310_110327_188781_5061F3D5 X-CRM114-Status: GOOD ( 18.91 ) 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 04:37:44PM +0000, Suzuki Kuruppassery Poulose wrote: [...] > > 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. > > Not really possible. There could be systems with mixed sinks. e.g. TRBE > for some CPU and ETR for others (say due to a non-functioning TRBE). > > > - If users don't set the flag, perf tool detects it is ETF/ETB/ETR > > sinks, it sets the flag as true. > > And in the cases above, perf event cannot run on all the CPUs, because > some sinks don't support it. > > Why do we need a flag, when the effect is not user (read, perf decoder) > visible and at the same time improves some scenarios (read non-TRBE cases) > ? Indeed in this case the flag is redundant. > I would say, let the driver always update on pause, depending on the > sink. It is fine for me. I will move towards this direction. Thanks, Leo