From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from desiato.infradead.org (desiato.infradead.org [90.155.92.199]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id 02937399CEF; Wed, 13 May 2026 07:28:41 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=90.155.92.199 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1778657324; cv=none; b=Sa2FWtZN47s+qsCtIf32bJ7dh0gtT8a1BcTEHwuAnR3kPkpDUsm3BbDbeHkMbYmQLmSGdPXxFp+rKsg1f4aZq+lcE7NGgXqdiiwDk0umOeIiwLAWxBsSucIxX6+7t9mxL2UbtDeaVZPGEh5hIstt4uSNnE9McbyiFqyufshzVLE= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1778657324; c=relaxed/simple; bh=42AOEQUBwBuB/gmOZDF1E+KjyLk6+r/HsuYZ6WksJ6Q=; h=Date:From:To:Cc:Subject:Message-ID:References:MIME-Version: Content-Type:Content-Disposition:In-Reply-To; b=QmyOmM2sPH33jGuEKCD58BZEbvu/0R4+dj/QnJEjWu/N1xRjI/KEjUibivHYUbS1MipZMNqVVnBxmrBL/JC9boangVLkrY+V4ddLizq/Mrikp0LN9MVmyQ0LKhdiqZumG2qxRKqwu+bpi9ajtDuiTpoElsl1UG21qHdlgNdenw0= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=infradead.org; spf=none smtp.mailfrom=infradead.org; dkim=pass (2048-bit key) header.d=infradead.org header.i=@infradead.org header.b=hdnvmLqQ; arc=none smtp.client-ip=90.155.92.199 Authentication-Results: smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=infradead.org Authentication-Results: smtp.subspace.kernel.org; spf=none smtp.mailfrom=infradead.org Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=infradead.org header.i=@infradead.org header.b="hdnvmLqQ" DKIM-Signature: v=1; a=rsa-sha256; q=dns/txt; c=relaxed/relaxed; d=infradead.org; s=desiato.20200630; h=In-Reply-To:Content-Type:MIME-Version: References:Message-ID:Subject:Cc:To:From:Date:Sender:Reply-To: Content-Transfer-Encoding:Content-ID:Content-Description; bh=IzAGYMx7uDKCue0uiQSrq/gponLm1tivP9HcSrBDwgA=; b=hdnvmLqQs6guRjQjvCX0NFJVm7 YhtDeOblM8X8e889e6yAQRxKU0Tdx5JU+J5bQv4Y4A0stPRzmcgMUm6pGwG3cT3aFKEGPqgdQsb33 1RDSjzGDa91HM6cBy25tTl1g8WwKoPWVT1kxofV9t9JN18dReuvupdX0sxVIxL8iI1CV4MIOJSWrr ogGc5atGPqdvBEC1tAX+MUgVQOCSpT6st6w6ocFmEXYeVQngWRp0PzUe8oCa4e4rWG918xH1nodzx WoUDJ5oqqhuvMw3uw+FRxPJy6z9f4Nh9epkuF8IxyQ7SpWX2bsHLW6k8cGiks5D52L9LmMBzNx4WL p5gRzFVA==; Received: from 2001-1c00-8d85-4b00-266e-96ff-fe07-7dcc.cable.dynamic.v6.ziggo.nl ([2001:1c00:8d85:4b00:266e:96ff:fe07:7dcc] helo=noisy.programming.kicks-ass.net) by desiato.infradead.org with esmtpsa (Exim 4.99.1 #2 (Red Hat Linux)) id 1wN3xs-0000000GlIj-47MZ; Wed, 13 May 2026 07:27:00 +0000 Received: by noisy.programming.kicks-ass.net (Postfix, from userid 1000) id BE766300B8A; Wed, 13 May 2026 09:25:07 +0200 (CEST) Date: Wed, 13 May 2026 09:25:07 +0200 From: Peter Zijlstra To: Vincent Guittot Cc: mingo@kernel.org, longman@redhat.com, chenridong@huaweicloud.com, juri.lelli@redhat.com, dietmar.eggemann@arm.com, rostedt@goodmis.org, bsegall@google.com, mgorman@suse.de, vschneid@redhat.com, tj@kernel.org, hannes@cmpxchg.org, mkoutny@suse.com, cgroups@vger.kernel.org, linux-kernel@vger.kernel.org, jstultz@google.com, kprateek.nayak@amd.com, qyousef@layalina.io Subject: Re: [PATCH v2 00/10] sched: Flatten the pick Message-ID: <20260513072507.GE1889694@noisy.programming.kicks-ass.net> References: <20260511113104.563854162@infradead.org> <20260512092040.GN3102624@noisy.programming.kicks-ass.net> <20260512182439.GA2855641@noisy.programming.kicks-ass.net> <20260512182530.GB2855641@noisy.programming.kicks-ass.net> Precedence: bulk X-Mailing-List: linux-kernel@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 Tue, May 12, 2026 at 08:32:12PM +0200, Vincent Guittot wrote: > On Tue, 12 May 2026 at 20:25, Peter Zijlstra wrote: > > > > On Tue, May 12, 2026 at 08:24:39PM +0200, Peter Zijlstra wrote: > > > On Tue, May 12, 2026 at 11:20:40AM +0200, Peter Zijlstra wrote: > > > > On Tue, May 12, 2026 at 10:42:33AM +0200, Vincent Guittot wrote: > > > > > > > > > > > > > > I haven't reviewed the patches yet but I ran some tests with it while > > > > > testing sched latency related changes for short slice wakeup > > > > > preemption. I have some large hackbench regressions with this series > > > > > on HMP system with and without EAS. those figures are unexpected > > > > > because the benchs run on root cfs > > > > > > > > > > One example with hackbench 8 groups thread pipe > > > > > tip/sched/core tip/sched/core +this patchset +this patchset > > > > > slice 2.8ms 16ms 2.8ms 16ms > > > > > dragonboard rb5 with EAS > > > > > 0,748(+/-4,6%) 0,621(+/-3.6%) +17% 1,915(+/-7.9%) -156% > > > > > 0,689(+/- 9.1%) +8% > > > > > > > > > > radxa orion6 HMP without EAS > > > > > 0,588(+/-5.8%) 0,677(+/-5.9%) -15% 1,505(+/-10%) -156% > > > > > 1,071(+/-5.9%) -82% > > > > > > > > > > Increasing the slice partly removes regressions but tis is surprising > > > > > because the bench runs at root cfs and I thought that results will not > > > > > change in such a case > > > > > > > > > > I will review the patchset and try to get what is going wrong > > > > > > > > Yeah, that is unexpected. Let me go have another look too. > > > > > > So I can reproduce even without the last patch applied. I suspect it is > > > in the cgroup mode patches somewhere. My first suspect is that concur > > > mode thing doing bad things to track the 'global' nr_running thing. > > > > Argh, n/m PEBKAC. I'll try this again in the morning :/ > > Reverting the last patch is enough to recover performance Yeah, I was on a fail-streak yesterday. I forgot to copy the kernel image before reboot ... Lets see if today is better :-)