From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from foss.arm.com (foss.arm.com [217.140.110.172]) by smtp.subspace.kernel.org (Postfix) with ESMTP id 7BDDE1F4CAC; Tue, 27 May 2025 09:49:30 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=217.140.110.172 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1748339372; cv=none; b=nXe4oRA+yyMNu5F0h413z1a/U6XAz/gnUwS3+8upmeG1mxizYBxynSchZwh4JgmIpXpOXL6DHpfK461KJuhmYifEaF0IqmKWoF8k3cl4+2lE2nR2GIaGQS65zwsG1Cw6rqVgWU+ZIlt7IMbgfI1Z0+kXSpeugwGIvPFzl9/sGWs= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1748339372; c=relaxed/simple; bh=+h6UbpfiTWqp32wSjTJpECkbEu5qI0YU/w+MW0bl3ts=; h=Date:From:To:Cc:Subject:Message-ID:References:MIME-Version: Content-Type:Content-Disposition:In-Reply-To; b=czyXKAZg7k2G1vnSfZSveOgQ3L2dhMlfXJxR84B8kCepXl0hvJpGY/bhgfagw4klTBn5oyyMEGOgPAJoL9+7FS9Pp7+JOkRcqTrBZ7irOKcfCQMOMY6X2ifLeGkuSUCaHpSjsrqmYc22ZElnk1kzeVViqc499/thGz+fPG6bT5E= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=arm.com; spf=pass smtp.mailfrom=arm.com; arc=none smtp.client-ip=217.140.110.172 Authentication-Results: smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=arm.com Authentication-Results: smtp.subspace.kernel.org; spf=pass smtp.mailfrom=arm.com 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 7FF7A14BF; Tue, 27 May 2025 02:49:13 -0700 (PDT) Received: from localhost (e132581.arm.com [10.1.196.87]) by usa-sjc-imap-foss1.foss.arm.com (Postfix) with ESMTPSA id 0C6083F673; Tue, 27 May 2025 02:49:28 -0700 (PDT) Date: Tue, 27 May 2025 10:49:24 +0100 From: Leo Yan To: Arnaldo Carvalho de Melo Cc: Namhyung Kim , Ian Rogers , Adrian Hunter , "Liang, Kan" , James Clark , linux-perf-users@vger.kernel.org, linux-kernel@vger.kernel.org Subject: Re: [PATCH] perf tests switch-tracking: Fix timestamp comparison Message-ID: <20250527094924.GF2566836@e132581.arm.com> References: <20250331172759.115604-1-leo.yan@arm.com> <20250523081036.GB2566836@e132581.arm.com> Precedence: bulk X-Mailing-List: linux-perf-users@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: On Fri, May 23, 2025 at 02:12:58PM -0300, Arnaldo Carvalho de Melo wrote: [...] > Thanks for the extra info, I'll add it to the commit log message, and > perhaps we could make this test exclusive and use stress-ng to generate > some background noise in the form of a good number of processes, see: > > root@x1:~# stress-ng --switch $(($(nproc) * 2)) --timeout 30s & for a in $(seq 50) ; do perf test switch ; done Thanks for sharing the test command. > Now with your patch it also fails, so its for another reason: > > --- start --- > test child forked, pid 1777071 > Using CPUID GenuineIntel-6-BA-3 > mmap size 528384B > 45221 events recorded > Missing comm events > ---- end(-1) ---- > 113: Track with sched_switch : FAILED! > > Lots of short lived processes makes it fail as well :-\ I searched internal CI record, we also occasionally saw the error: Missing cycles events I will find time to check if anything in test can be improved. Seems to me, the test is fragile if system has background activities. > Your patch is correct, so I'll probably just add your comments and go > with it. Thanks! Also thanks Ian's suggestion for the iteration command. Leo