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=-15.3 required=3.0 tests=BAYES_00, HEADER_FROM_DIFFERENT_DOMAINS,INCLUDES_CR_TRAILER,INCLUDES_PATCH, MAILING_LIST_MULTI,NICE_REPLY_A,SPF_HELO_NONE,SPF_PASS,USER_AGENT_SANE_1 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 1AF6FC433ED for ; Fri, 16 Apr 2021 12:51:32 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id E05F261107 for ; Fri, 16 Apr 2021 12:51:31 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S239117AbhDPMvz (ORCPT ); Fri, 16 Apr 2021 08:51:55 -0400 Received: from foss.arm.com ([217.140.110.172]:40762 "EHLO foss.arm.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S235074AbhDPMvx (ORCPT ); Fri, 16 Apr 2021 08:51:53 -0400 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 AAD8411B3; Fri, 16 Apr 2021 05:51:28 -0700 (PDT) Received: from [10.57.57.112] (unknown [10.57.57.112]) by usa-sjc-imap-foss1.foss.arm.com (Postfix) with ESMTPSA id 99AA23F85F; Fri, 16 Apr 2021 05:51:26 -0700 (PDT) Subject: Re: [PATCH v4 4/6] perf arm-spe: Assign kernel time to synthesized event To: Leo Yan Cc: Arnaldo Carvalho de Melo , Al Grant , John Garry , Will Deacon , Mathieu Poirier , Peter Zijlstra , Ingo Molnar , Mark Rutland , Alexander Shishkin , Jiri Olsa , Namhyung Kim , Adrian Hunter , Dave Martin , linux-arm-kernel@lists.infradead.org, linux-kernel@vger.kernel.org References: <20210412091006.468557-1-leo.yan@linaro.org> <20210412091006.468557-5-leo.yan@linaro.org> <9036368a-e824-3d63-da5b-54cf32a86aed@arm.com> <20210415152348.GF1011890@leoy-ThinkPad-X240s> From: James Clark Message-ID: Date: Fri, 16 Apr 2021 15:51:25 +0300 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:68.0) Gecko/20100101 Thunderbird/68.10.0 MIME-Version: 1.0 In-Reply-To: <20210415152348.GF1011890@leoy-ThinkPad-X240s> Content-Type: text/plain; charset=utf-8 Content-Language: en-US Content-Transfer-Encoding: 7bit Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On 15/04/2021 18:23, Leo Yan wrote: > On Thu, Apr 15, 2021 at 05:46:31PM +0300, James Clark wrote: >> >> >> On 12/04/2021 12:10, Leo Yan wrote: >>> In current code, it assigns the arch timer counter to the synthesized >>> samples Arm SPE trace, thus the samples don't contain the kernel time >>> but only contain the raw counter value. >>> >>> To fix the issue, this patch converts the timer counter to kernel time >>> and assigns it to sample timestamp. >>> >>> Signed-off-by: Leo Yan >>> --- >>> tools/perf/util/arm-spe.c | 2 +- >>> 1 file changed, 1 insertion(+), 1 deletion(-) >>> >>> diff --git a/tools/perf/util/arm-spe.c b/tools/perf/util/arm-spe.c >>> index 23714cf0380e..c13a89f06ab8 100644 >>> --- a/tools/perf/util/arm-spe.c >>> +++ b/tools/perf/util/arm-spe.c >>> @@ -234,7 +234,7 @@ static void arm_spe_prep_sample(struct arm_spe *spe, >>> struct arm_spe_record *record = &speq->decoder->record; >>> >>> if (!spe->timeless_decoding) >>> - sample->time = speq->timestamp; >>> + sample->time = tsc_to_perf_time(record->timestamp, &spe->tc); >> >> >> I noticed that in arm_spe_recording_options() the TIME sample bit is set regardless of any options. >> I don't know of a way to remove this, and if there isn't, does that mean that all the code in this >> file that looks at spe->timeless_decoding is untested and has never been hit? >> >> Unless there is a way to get a perf file with only the AUXTRACE event and no others? I think that one >> might have no timestamp set. Otherwise other events will always have timestamps so spe->timeless_decoding >> is always false. > > Good point. To be honest, I never noticed this issue until you > mentioned this. > > We should fix for the "timeless" flow; and it's questionable for the > function arm_spe_recording_options(), except for setting > PERF_SAMPLE_TIME, it also hard codes for setting > PERF_SAMPLE_CPU and PERF_SAMPLE_TID. Might need to carefully go > through this function. > Yeah, it's not strictly related to your change, which is definitely an improvement. But maybe we should have a look at the SPE implementation relating to timestamps as a whole. > Thanks, > Leo >