From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from casper.infradead.org (casper.infradead.org [90.155.50.34]) (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 DB0BB3A545C; Tue, 12 May 2026 09:21:01 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=90.155.50.34 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1778577665; cv=none; b=HKE16CfVu1qUCCSufMJnHsP0Z/CFU6LgtVtZHQe2jr6ry5qFIa5VjCeTxnVNBl29rdGfMAWbT6LWPvdUli6ps4RE3OtIIt646XXTFj66XqmBzrIQEx8leBhD37mVTRdfZvN5I28tFim2hRLBPVxeDYR1kuje69O6rRTQ1ug8sjE= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1778577665; c=relaxed/simple; bh=I258KXDlBOPbLpKTjlWvEvH+QZm8Pa5TcELdSEgQdYA=; h=Date:From:To:Cc:Subject:Message-ID:References:MIME-Version: Content-Type:Content-Disposition:In-Reply-To; b=bul9wP/z/kTzxL8hXTlf3Jl6K+qB56KCTfSgjL9Z7jeMGv8h0jJWrx0bdAskPmdTE1q+IccwYtR+uGmowh8p5qx7UP9FDLFjkA47Qj3n1E/WSZYmwegFBQBubU32oHk6VvVeAjFr67lhGBdvj+lZxeSqSfPDC+8fCmdtdno/9Kg= 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=q1cYlWRw; arc=none smtp.client-ip=90.155.50.34 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="q1cYlWRw" DKIM-Signature: v=1; a=rsa-sha256; q=dns/txt; c=relaxed/relaxed; d=infradead.org; s=casper.20170209; 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=r1noIgol6YRgrrmBWyBp/qexYp9bKrMg/AqV0MRqYVU=; b=q1cYlWRwiHXiE8xg3nfhaeeRbs PkNVEhYfZmPvW1gpObBnvEemhNfvfjm1bwBW0Hg+AaLk5zYGnsLK30js+l0qjifggkCGAsT0vs4lx 5teYnelbmnIzhN+rhLsOKHjwmNoMff+VNQO1CZd689DvvsmCe10dr/NG2FzUGade+12NPRiAjwdvN x7L5YKTd6Nhda+CDcSubqdhefKw8HVOXJVnTC5RnCsTPQ1fs0KYWUGJyDKxUQnZ7bfd6VUzCJ16pU TI9baKUNpyns43yxvyV144ajETlv/c5ZwZ1pL7aC+vxioy/oawYVY7cBPpfzeDyR3764oK5XUJkQL YJGGc+VA==; Received: from 77-249-17-252.cable.dynamic.v4.ziggo.nl ([77.249.17.252] helo=noisy.programming.kicks-ass.net) by casper.infradead.org with esmtpsa (Exim 4.99.1 #2 (Red Hat Linux)) id 1wMjI9-00000009ULy-1b2a; Tue, 12 May 2026 09:20:41 +0000 Received: by noisy.programming.kicks-ass.net (Postfix, from userid 1000) id 1CF7530095A; Tue, 12 May 2026 11:20:40 +0200 (CEST) Date: Tue, 12 May 2026 11:20:40 +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: <20260512092040.GN3102624@noisy.programming.kicks-ass.net> References: <20260511113104.563854162@infradead.org> Precedence: bulk X-Mailing-List: cgroups@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 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.