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 X-Spam-Level: X-Spam-Status: No, score=-2.6 required=3.0 tests=DKIM_SIGNED,DKIM_VALID, DKIM_VALID_AU,HEADER_FROM_DIFFERENT_DOMAINS,MAILING_LIST_MULTI,SPF_PASS, USER_AGENT_MUTT autolearn=ham autolearn_force=no version=3.4.0 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id 0192CC43441 for ; Sun, 18 Nov 2018 06:39:01 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id B194520815 for ; Sun, 18 Nov 2018 06:39:01 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (1024-bit key) header.d=linaro.org header.i=@linaro.org header.b="Dg4jEBV3" DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org B194520815 Authentication-Results: mail.kernel.org; dmarc=fail (p=none dis=none) header.from=linaro.org Authentication-Results: mail.kernel.org; spf=none smtp.mailfrom=linux-kernel-owner@vger.kernel.org Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1726862AbeKRQ6W (ORCPT ); Sun, 18 Nov 2018 11:58:22 -0500 Received: from mail-wm1-f68.google.com ([209.85.128.68]:51141 "EHLO mail-wm1-f68.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1725914AbeKRQ6W (ORCPT ); Sun, 18 Nov 2018 11:58:22 -0500 Received: by mail-wm1-f68.google.com with SMTP id 125so236459wmh.0 for ; Sat, 17 Nov 2018 22:38:58 -0800 (PST) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=linaro.org; s=google; h=date:from:to:cc:subject:message-id:references:mime-version :content-disposition:in-reply-to:user-agent; bh=dD7BzDCnhRhOgR3C0f/N2/i+PDSNifRbl9oSl1vDRvY=; b=Dg4jEBV3YSL6wxWztr1TdxDMq6YmHT1tFBNCxvvsdWzTH+lpKEhAiLCHuD+u9G1mMs 3/uGhv8N4q9O/cHNoBcEMEXaC3L5PchboLKPPvjFBFsIfJIl2YYsUxpbf8/eR9Q7k7P4 MQvWMz7jtkC+c4eofmrZ0CNQoSHdVW762OYfg= X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20161025; h=x-gm-message-state:date:from:to:cc:subject:message-id:references :mime-version:content-disposition:in-reply-to:user-agent; bh=dD7BzDCnhRhOgR3C0f/N2/i+PDSNifRbl9oSl1vDRvY=; b=AprX714WPbcXQAkW2rT7a7vdhQhYc2hemWd5f9JL7tfjYk76YuSebeLBBtXAkdbxDN exnXGR6xNCok5qp4M0/J1ZoEm9ifFUuOLWc2vSoMqX1GiNaxKi31PBhuzFFa9CZUtxHl F63bDOHiBN08ogYOlax4YiLC32rTBTDbSTGeaP8evaxSFwWRNqDVOYwCdeJOjM0iiGfw g8xv5UFMcnXDvnUnweAbyJ7Gwuz4zjwvvQSeQju5jezZj0o5WQNrB/JkAsT7nkr9rzrl dHNhnfP9fxHbu7YrGvU75DYuLiiwCzI5YjAXfS37YYM5OFNEqOLgkPhMe90ZRuHSc8NK jNyA== X-Gm-Message-State: AGRZ1gI4Wm2KIbbNu9wKv7lld22HNyCPaf8ZsH71RHT9lm4/IuXwtPkM rGhfD+QgmNC1CKh0VABhVD3pWA== X-Google-Smtp-Source: AFSGD/U/5ehsBcTfQIY55lNhIP6QX5ySHnAx/xJAs/edQPcqxysM+G/Ut8LmloPMcnr5S5vOVSoeog== X-Received: by 2002:a1c:9a46:: with SMTP id c67mr3150907wme.21.1542523137521; Sat, 17 Nov 2018 22:38:57 -0800 (PST) Received: from leoy-ThinkPad-X240s ([209.250.228.18]) by smtp.gmail.com with ESMTPSA id 133sm6193420wme.9.2018.11.17.22.38.52 (version=TLS1_2 cipher=ECDHE-RSA-AES128-GCM-SHA256 bits=128/128); Sat, 17 Nov 2018 22:38:56 -0800 (PST) Date: Sun, 18 Nov 2018 14:38:48 +0800 From: leo.yan@linaro.org To: Mathieu Poirier Cc: Arnaldo Carvalho de Melo , Alexander Shishkin , Jiri Olsa , Namhyung Kim , linux-arm-kernel@lists.infradead.org, linux-kernel@vger.kernel.org, Mike Leach , Robert Walker , Al Grant , Coresight ML Subject: Re: [PATCH v1 2/5] perf cs-etm: Avoid stale branch samples when flush packet Message-ID: <20181118063848.GA8751@leoy-ThinkPad-X240s> References: <1541912383-19915-1-git-send-email-leo.yan@linaro.org> <1541912383-19915-3-git-send-email-leo.yan@linaro.org> <20181116230511.GB25258@xps15> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20181116230511.GB25258@xps15> User-Agent: Mutt/1.10+31 (9cdd884) (2018-06-19) Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Fri, Nov 16, 2018 at 04:05:11PM -0700, Mathieu Poirier wrote: [...] > > -static int cs_etm__flush(struct cs_etm_queue *etmq) > > +static int cs_etm__flush(struct cs_etm_queue *etmq, bool new_packet) > > { > > int err = 0; > > struct cs_etm_auxtrace *etm = etmq->etm; > > @@ -989,6 +989,20 @@ static int cs_etm__flush(struct cs_etm_queue *etmq) > > > > } > > > > + /* > > + * If 'new_packet' is false, this time call has no a new packet > > + * coming and 'etmq->packet' contains the stale packet which is > > + * set at the previous time with packets swapping. In this case > > + * this function is invoked only for flushing branch stack at > > + * the end of buffer handling. > > + * > > + * Simply to say, branch samples should be generated when every > > + * time receive one new packet; otherwise, directly bail out to > > + * avoid generate branch sample with stale packet. > > + */ > > + if (!new_packet) > > + return 0; > > + > > if (etm->sample_branches && > > etmq->prev_packet->sample_type == CS_ETM_RANGE) { > > err = cs_etm__synth_branch_sample(etmq); > > @@ -1075,7 +1089,7 @@ static int cs_etm__run_decoder(struct cs_etm_queue *etmq) > > * Discontinuity in trace, flush > > * previous branch stack > > */ > > - cs_etm__flush(etmq); > > + cs_etm__flush(etmq, true); > > break; > > case CS_ETM_EMPTY: > > /* > > @@ -1092,7 +1106,7 @@ static int cs_etm__run_decoder(struct cs_etm_queue *etmq) > > > > if (err == 0) > > /* Flush any remaining branch stack entries */ > > - err = cs_etm__flush(etmq); > > + err = cs_etm__flush(etmq, false); > > I understand what you're doing and it will yield the correct results. What I'm > not sure about is if we wouldn't be better off splitting cs_etm__flush() > in order to reduce the complexity of the main decoding loop. That is rename > cs_etm__flush() to something like cs_etm__trace_on() and spin off a new > cs_etm__end_block(). > > It does introduce a little bit of code duplication but I think we'd win in terms > of readability and flexibility. Thanks for reviewing, Mathieu. I agree with your suggestion to split cs_etm__flush() into two functions, will spin this patch with the suggestion in next series for reviewing. Thanks, Leo Yan