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 43AF222A4C3 for ; Mon, 10 Mar 2025 15:29:18 +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=1741620561; cv=none; b=r4QOm7bVQx7h4j85lJ3643Z9cn02tdT/l9erUjyb2hWAt+K6XgBSi2h9Tpbe81nnYDlF4kFOZrqkSL+ZQzACDcbq625gwJkM+YeE0SKz0oLL5GqX85vp3yEVWhLaGk7LgLNt8VXZbAVgRfWFZG0e/jNKDe25HCLwuHk3fVimNI4= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1741620561; c=relaxed/simple; bh=9jsHEIUilFU+hAzGMJpulbNlAJCkWu5A0q07RLupo0I=; h=Message-ID:Date:MIME-Version:Subject:To:Cc:References:From: In-Reply-To:Content-Type; b=H9jIpN5qhZb79q9/9gWrJOuYcXc510GzGWl+mSEqvW+MpAd9EuX6cBxS2Nst08kkW8jsHR+QxljfGodri2SbwHRgOOoIboiAwq6VrdQ1JOrKmVD7m8icE7l38zLAE0HT4RyR3PjuNeKCpDY17Nr5i647ET+DHHbqRDpOlSSCMLU= 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 EE07D1692; Mon, 10 Mar 2025 08:29:29 -0700 (PDT) Received: from [192.168.178.6] (usa-sjc-mx-foss1.foss.arm.com [172.31.20.19]) by usa-sjc-imap-foss1.foss.arm.com (Postfix) with ESMTPSA id DCFAF3F5A1; Mon, 10 Mar 2025 08:29:16 -0700 (PDT) Message-ID: <8ddd7bb2-3a18-48b5-85c6-23263134308a@arm.com> Date: Mon, 10 Mar 2025 16:29:10 +0100 Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 User-Agent: Mozilla Thunderbird Subject: Re: [PATCH] /sched/core: Fix Unixbench spawn test regression To: Vincent Guittot Cc: Ingo Molnar , Peter Zijlstra , Juri Lelli , Steven Rostedt , Ben Segall , Mel Gorman , Valentin Schneider , Hagar Hemdan , linux-kernel@vger.kernel.org, wuchi.zero@gmail.com References: <20250306162635.2614376-1-dietmar.eggemann@arm.com> From: Dietmar Eggemann Content-Language: en-US In-Reply-To: Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 7bit On 10/03/2025 14:59, Vincent Guittot wrote: > On Thu, 6 Mar 2025 at 17:26, Dietmar Eggemann wrote: >> >> Hagar reported a 30% drop in UnixBench spawn test with commit >> eff6c8ce8d4d ("sched/core: Reduce cost of sched_move_task when config >> autogroup") on a m6g.xlarge AWS EC2 instance with 4 vCPUs and 16 GiB RAM >> (aarch64) (single level MC sched domain) [1]. >> >> There is an early bail from sched_move_task() if p->sched_task_group is >> equal to p's 'cpu cgroup' (sched_get_task_group()). E.g. both are >> pointing to taskgroup '/user.slice/user-1000.slice/session-1.scope' >> (Ubuntu '22.04.5 LTS'). > > Isn't this same use case that has been used by commit eff6c8ce8d4d to > show the benefit of adding the test if ((group == > tsk->sched_task_group) ? > Adding Wuchi who added the condition IMHO, UnixBench spawn reports a performance number according to how many tasks could be spawned whereas, IIUC, commit eff6c8ce8d4d was reporting the time spend in sched_move_task(). [...]