Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1752514AbcCYHc1 (ORCPT ); Fri, 25 Mar 2016 03:32:27 -0400 Received: from mail-yw0-f174.google.com ([209.85.161.174]:35585 "EHLO mail-yw0-f174.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752008AbcCYHcY (ORCPT ); Fri, 25 Mar 2016 03:32:24 -0400 MIME-Version: 1.0 In-Reply-To: <56F3F4F5.8050200@fb.com> References: <05d6338bddae751c1755e7825d4179658e78cc71.1458819912.git.baolin.wang@linaro.org> <56F3F4F5.8050200@fb.com> Date: Fri, 25 Mar 2016 15:32:23 +0800 Message-ID: Subject: Re: [PATCH] mmc: Provide tracepoints for request processing From: Baolin Wang To: Jens Axboe Cc: Ulf Hansson , rostedt@goodmis.org, mingo@redhat.com, adrian.hunter@intel.com, yangbo.lu@freescale.com, akpm@linux-foundation.org, JBottomley@odin.com, lporzio@micron.com, jonathanh@nvidia.com, grundler@chromium.org, fabf@skynet.be, yunpeng.gao@intel.com, dan.j.williams@intel.com, rabin.vincent@axis.com, chuanxiao.dong@intel.com, shawn.lin@rock-chips.com, heiko@sntech.de, dianders@chromium.org, david@protonic.nl, Mark Brown , Linus Walleij , Takahiro Akashi , LKML , linux-mmc@vger.kernel.org Content-Type: text/plain; charset=UTF-8 Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 887 Lines: 27 On 24 March 2016 at 22:08, Jens Axboe wrote: > On 03/24/2016 05:54 AM, Baolin Wang wrote: >> >> This patch provides some tracepoints for the lifecycle of a request from >> fetching to completion to help with performance analysis of MMC subsystem. > > > Most of these already exist as block layer trace points, why do we need mmc > specific ones? Currently the MMC core does not have any tracepoints for use with ftrace. These are very useful as they provide a very low overhead runtime controllable way of getting diagnostics from the system which is capable of recording a great deal of information without impacting system performance. We have tracepoints in the block layer so we can do some trace of MMC but none in MMC itself so adding some where appropriate would help people follow the activity of subsystem. > > > -- > Jens Axboe > -- Baolin.wang Best Regards