Received: by 2002:a05:6a10:206:0:0:0:0 with SMTP id 6csp654179pxj; Thu, 10 Jun 2021 09:28:50 -0700 (PDT) X-Google-Smtp-Source: ABdhPJyBUKS2H1b1fcYbhvWJ7q/WRWaYnH6p4D8difGYrZhkVfZVNhCDUP891xDNvM67+Q6XTTqy X-Received: by 2002:a17:906:b352:: with SMTP id cd18mr428823ejb.222.1623342529925; Thu, 10 Jun 2021 09:28:49 -0700 (PDT) ARC-Seal: i=1; a=rsa-sha256; t=1623342529; cv=none; d=google.com; s=arc-20160816; b=q4hH1iQap0y0zyDD+7P1gCIK7iL8ygGmI98GLe3oEprrDKg6WNTR7W1mP4vXXN4IDl MMPXnBTIXT54KQSFuEAOzF1iutfmAe8/mvTuP+aC4bLMaDFGeSqN3sSoqGipbEl197bA TmwqLVlZgIijS8YtjRymtSgl7KY65WPvHwzw1vB+bnodoo3bka7yLR/Y0Pk262mJSU7R ctBjrgz7waEsWWIEMgAwvFVOKmTwPfX5Erclg/AyBWF4GsPzbIKlvRffmS2TrUg1kUt9 z/wMTS3lfWZ+aHXiaeqyKayoMTFqLX3w1OrsIMNRHbEh81x47fqVL43h61MUOV/Ieaz6 YwoQ== ARC-Message-Signature: i=1; a=rsa-sha256; c=relaxed/relaxed; d=google.com; s=arc-20160816; h=list-id:precedence:in-reply-to:content-disposition:mime-version :references:message-id:subject:cc:to:from:date:dkim-signature; bh=VN0XVB///d61kKRXkCK9H/d2Ol9ZLrpAFz4mHjzp1Zc=; b=G9ObzQlnMYUmJMMFN4SpgHkg0xdnhw9aChpOIMCoxkywFA2Cr1f7ziT0WjaKtNQs0T FT9RgwQgNPaqCM/UA34TX5xbaBeuvzTjqG6SNFznYlXhtMpDzKgp4uIqVtQsvPBRzspf QouR48XbLCx0M6GqasoOlDZFXwzWpHOEOSyxWk524mQeU8vfw5GiZHTEMccFGnS9pt0b k8qRR52dRPZHj57kHgqTspCYBSO2ROxggejxFDUSbCy/sBe8fjT5FxXFgmd2LzC4T5zI IWOYRS57DMtZk7aIQOkBwq4EqyM5aB9XOqfv8FjjHix2mdVcocK+UNkqhAJZ9beo1f4B dJxg== ARC-Authentication-Results: i=1; mx.google.com; dkim=pass header.i=@linaro.org header.s=google header.b=ix9fD5LA; spf=pass (google.com: domain of linux-kernel-owner@vger.kernel.org designates 23.128.96.18 as permitted sender) smtp.mailfrom=linux-kernel-owner@vger.kernel.org; dmarc=pass (p=NONE sp=NONE dis=NONE) header.from=linaro.org Return-Path: Received: from vger.kernel.org (vger.kernel.org. [23.128.96.18]) by mx.google.com with ESMTP id h6si2442555eds.229.2021.06.10.09.28.25; Thu, 10 Jun 2021 09:28:49 -0700 (PDT) Received-SPF: pass (google.com: domain of linux-kernel-owner@vger.kernel.org designates 23.128.96.18 as permitted sender) client-ip=23.128.96.18; Authentication-Results: mx.google.com; dkim=pass header.i=@linaro.org header.s=google header.b=ix9fD5LA; spf=pass (google.com: domain of linux-kernel-owner@vger.kernel.org designates 23.128.96.18 as permitted sender) smtp.mailfrom=linux-kernel-owner@vger.kernel.org; dmarc=pass (p=NONE sp=NONE dis=NONE) header.from=linaro.org Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S231345AbhFJQ0y (ORCPT + 99 others); Thu, 10 Jun 2021 12:26:54 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:43312 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S231341AbhFJQ0x (ORCPT ); Thu, 10 Jun 2021 12:26:53 -0400 Received: from mail-pj1-x102e.google.com (mail-pj1-x102e.google.com [IPv6:2607:f8b0:4864:20::102e]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 304E8C061760 for ; Thu, 10 Jun 2021 09:24:57 -0700 (PDT) Received: by mail-pj1-x102e.google.com with SMTP id o17-20020a17090a9f91b029015cef5b3c50so4048173pjp.4 for ; Thu, 10 Jun 2021 09:24:57 -0700 (PDT) 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; bh=VN0XVB///d61kKRXkCK9H/d2Ol9ZLrpAFz4mHjzp1Zc=; b=ix9fD5LAnx1QqJV/6k2ss+1TfixF9sf8viMtveQRBWj1NMBx0MoehFRGfgYbERv3pP TGDwriYmSD+N4RUW77j9cMTdmUxWzXAZ11KyTVYTxpGBntElM72bFq5FPHd++H3PhuL/ odKoaFI5GdEyhSrj3fVsOUBIpgYjlvKFP6F0fnUOkISHK7emRx1aNPHZ5+SedGSu0881 sirBIf4SdgL6Ml+OVi2tntv5APuhU9mAdYv8Wf5UHmNR+g84ryM9l98BnNCRlG2gZcR9 G/qWxynDdEOAW+Fssh1jyu09oUCqwSnl9+I97otExFus0cwiVY41fe8akxVtdiYd9LTc Lz4g== 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; bh=VN0XVB///d61kKRXkCK9H/d2Ol9ZLrpAFz4mHjzp1Zc=; b=a9JR6wC5m/v1aHL7Im0mnEGV0g3I83P0nUV5yMcyM6WsNdC4E5OmE2EePxKHYkS3rD 7aP9Dxx0etI2oAWIuyvQ8+Dize5DjSOo5JTo1cNjvSqKndT7CdPcVjzZAiwW4ai/xJye FOAQEyNHZkf1uVSD/fSYEH9mGbUT6ZuglHt0hKSXct3bL7HkRD5H0u5Z1AGYrdeOCNkv 9deiIVaxDTG4NJvUvad4QGeF6YXKWj3biOB/VnPPbhdHI+ee0NwVG0hMrILyuyBMZyO5 MQUVCu6hZxo0ppIpaRYaCI8SaHy9a0s0GSuGRufOgfvFHTCoLb35Z+leEhwnBV7r/6/K WNFQ== X-Gm-Message-State: AOAM530IjnFmNqWFaOUYAQ/wXvNbg4Ay8AoBQwkMns3V8rNofov0VdaP 75zjzdjFAJiXp8A4aFej+3BYkA== X-Received: by 2002:a17:90a:744d:: with SMTP id o13mr4290348pjk.34.1623342296573; Thu, 10 Jun 2021 09:24:56 -0700 (PDT) Received: from p14s (S0106889e681aac74.cg.shawcable.net. [68.147.0.187]) by smtp.gmail.com with ESMTPSA id e188sm2905217pfe.23.2021.06.10.09.24.54 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Thu, 10 Jun 2021 09:24:55 -0700 (PDT) Date: Thu, 10 Jun 2021 10:24:53 -0600 From: Mathieu Poirier To: James Clark Cc: acme@kernel.org, coresight@lists.linaro.org, leo.yan@linaro.org, al.grant@arm.com, branislav.rankov@arm.com, denik@chromium.org, suzuki.poulose@arm.com, anshuman.khandual@arm.com, Mike Leach , John Garry , Will Deacon , Mark Rutland , Alexander Shishkin , Jiri Olsa , Namhyung Kim , linux-arm-kernel@lists.infradead.org, linux-perf-users@vger.kernel.org, linux-kernel@vger.kernel.org Subject: Re: [PATCH] perf cs-etm: Delay decode of non-timeless data until cs_etm__flush_events() Message-ID: <20210610162453.GC34238@p14s> References: <20210609130421.13934-1-james.clark@arm.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20210609130421.13934-1-james.clark@arm.com> Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org This patch doesn't apply on coresight next. On Wed, Jun 09, 2021 at 04:04:20PM +0300, James Clark wrote: > Currently, timeless mode starts the decode on PERF_RECORD_EXIT, and > non-timeless mode starts decoding on the fist PERF_RECORD_AUX record. > > This can cause the "data has no samples!" error if the first > PERF_RECORD_AUX record comes before the first (or any relevant) > PERF_RECORD_MMAP2 record because the mmaps are required by the decoder > to access the binary data. > > This change pushes the start of non-timeless decoding to the very end of > parsing the file. The PERF_RECORD_EXIT event can't be used because it > might not exist in system-wide or snapshot modes. > > I have not been able to find the exact cause for the events to be > intermittently in the wrong order in the basic scenario: > > perf record -e cs_etm/@tmc_etr0/u top > > But it can be made to happen every time with the --delay option. This is > because "enable_on_exec" is disabled, which causes tracing to start > before the process to be launched is exec'd. For example: > > perf record -e cs_etm/@tmc_etr0/u --delay=1 top > perf report -D | grep 'AUX\|MAP' > > 0 16714475632740 0x520 [0x40]: PERF_RECORD_AUX offset: 0 size: 0x30 flags: 0 [] > 0 16714476494960 0x5d0 [0x40]: PERF_RECORD_AUX offset: 0x30 size: 0x30 flags: 0 [] > 0 16714478208900 0x660 [0x40]: PERF_RECORD_AUX offset: 0x60 size: 0x30 flags: 0 [] > 4294967295 16714478293340 0x700 [0x70]: PERF_RECORD_MMAP2 8712/8712: [0x557a460000(0x54000) @ 0 00:17 5329258 0]: r-xp /usr/bin/top > 4294967295 16714478353020 0x770 [0x88]: PERF_RECORD_MMAP2 8712/8712: [0x7f86f72000(0x34000) @ 0 00:17 5214354 0]: r-xp /usr/lib/aarch64-linux-gnu/ld-2.31.so > > Another scenario in which decoding from the first aux record fails is a > workload that forks. Although the aux record comes after 'bash', it > comes before 'top', which is what we are interested in. For example: > > perf record -e cs_etm/@tmc_etr0/u -- bash -c top > perf report -D | grep 'AUX\|MAP' > > 4294967295 16853946421300 0x510 [0x70]: PERF_RECORD_MMAP2 8723/8723: [0x558f280000(0x142000) @ 0 00:17 5213953 0]: r-xp /usr/bin/bash > 4294967295 16853946543560 0x580 [0x88]: PERF_RECORD_MMAP2 8723/8723: [0x7fbba6e000(0x34000) @ 0 00:17 5214354 0]: r-xp /usr/lib/aarch64-linux-gnu/ld-2.31.so > 4294967295 16853946628420 0x608 [0x68]: PERF_RECORD_MMAP2 8723/8723: [0x7fbba9e000(0x1000) @ 0 00:00 0 0]: r-xp [vdso] > 0 16853947067300 0x690 [0x40]: PERF_RECORD_AUX offset: 0 size: 0x3a60 flags: 0 [] > ... > 0 16853966602580 0x1758 [0x40]: PERF_RECORD_AUX offset: 0xc2470 size: 0x30 flags: 0 [] > 4294967295 16853967119860 0x1818 [0x70]: PERF_RECORD_MMAP2 8723/8723: [0x5559e70000(0x54000) @ 0 00:17 5329258 0]: r-xp /usr/bin/top > 4294967295 16853967181620 0x1888 [0x88]: PERF_RECORD_MMAP2 8723/8723: [0x7f9ed06000(0x34000) @ 0 00:17 5214354 0]: r-xp /usr/lib/aarch64-linux-gnu/ld-2.31.so > 4294967295 16853967237180 0x1910 [0x68]: PERF_RECORD_MMAP2 8723/8723: [0x7f9ed36000(0x1000) @ 0 00:00 0 0]: r-xp [vdso] > > A third scenario is when the majority of time is spent in a shared > library that is not loaded at startup. For example a dynamically loaded > plugin. > > Testing > ======= > > Testing was done by checking if any samples that are present in the > old output are missing from the new output. Timestamps must be > stripped out with awk because now they are set to the last AUX sample, > rather than the first: > > ./perf script $4 | awk '!($4="")' > new.script > ./perf-default script $4 | awk '!($4="")' > default.script > comm -13 <(sort -u new.script) <(sort -u default.script) > > Testing showed that the new output is a superset of the old. When lines > appear in the comm output, it is not because they are missing but > because [unknown] is now resolved to sensible locations. For example > last putp branch here now resolves to libtinfo, so it's not missing > from the output, but is actually improved: > > Old: > top 305 [001] 1 branches:uH: 402830 _init+0x30 (/usr/bin/top.procps) => 404a1c [unknown] (/usr/bin/top.procps) > top 305 [001] 1 branches:uH: 404a20 [unknown] (/usr/bin/top.procps) => 402970 putp@plt+0x0 (/usr/bin/top.procps) > top 305 [001] 1 branches:uH: 40297c putp@plt+0xc (/usr/bin/top.procps) => 0 [unknown] ([unknown]) > New: > top 305 [001] 1 branches:uH: 402830 _init+0x30 (/usr/bin/top.procps) => 404a1c [unknown] (/usr/bin/top.procps) > top 305 [001] 1 branches:uH: 404a20 [unknown] (/usr/bin/top.procps) => 402970 putp@plt+0x0 (/usr/bin/top.procps) > top 305 [001] 1 branches:uH: 40297c putp@plt+0xc (/usr/bin/top.procps) => 7f8ab39208 putp+0x0 (/lib/libtinfo.so.5.9) > > In the following two modes, decoding now works and the "data has no > samples!" error is not displayed any more: > > perf record -e cs_etm/@tmc_etr0/u -- bash -c top > perf record -e cs_etm/@tmc_etr0/u --delay=1 top > > In snapshot mode, there is also an improvement to decoding. Previously > samples for the 'kill' process that was used to send SIGUSR2 were > completely missing, because the process hadn't started yet. But now > there are additional samples present: > > perf record -e cs_etm/@tmc_etr0/u --snapshot -a > perf script > > stress 19380 [003] 161627.938153: 1000000 instructions:uH: aaaabb612fb4 [unknown] (/usr/bin/stress) > kill 19644 [000] 161627.938153: 1000000 instructions:uH: ffffae0ef210 [unknown] (/lib/aarch64-linux-gnu/ld-2.27.so) > stress 19380 [003] 161627.938153: 1000000 instructions:uH: ffff9e754d40 random_r+0x20 (/lib/aarch64-linux-gnu/libc-2.27.so) > > Also tested was the round trip of 'perf inject' followed by 'perf > report' which has the same differences and improvements. > > Signed-off-by: James Clark > --- > tools/perf/util/cs-etm.c | 6 +++++- > 1 file changed, 5 insertions(+), 1 deletion(-) > > diff --git a/tools/perf/util/cs-etm.c b/tools/perf/util/cs-etm.c > index 57aea2c7fc77..ceed0b038796 100644 > --- a/tools/perf/util/cs-etm.c > +++ b/tools/perf/util/cs-etm.c > @@ -2407,6 +2407,11 @@ static int cs_etm__process_event(struct perf_session *session, > return err; > } > > + /* > + * Don't wait for cs_etm__flush_events() in per-thread/timeless mode to start the decode. We > + * need the tid of the PERF_RECORD_EXIT event to assign to the synthesised samples because > + * ETM_OPT_CTXTID is not enabled. > + */ > if (etm->timeless_decoding && > event->header.type == PERF_RECORD_EXIT) > return cs_etm__process_timeless_queues(etm, > @@ -2424,7 +2429,6 @@ static int cs_etm__process_event(struct perf_session *session, > * onwards. > */ > etm->latest_kernel_timestamp = sample_kernel_timestamp; > - return cs_etm__process_queues(etm); > } > > return 0; > -- > 2.28.0 >