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 0EC1545A2BD for ; Wed, 2 Sep 2026 10:37:27 +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=1788345452; cv=none; b=OZPRALEP6bBuSs/ldKNpXYumNYNZN+NesKQO/WCRDbjPGI/vKgIK0MaHO4Fu0ZTlHfsxezC1W29oavGO5o3nr1LtOKKEz4PNVbPKRHF181Yy1cCXD0LfuCHq8A1/g0WHFFAhzlk7hBZsWqVP5C+5ENO/rbRPSwfFoBOwCz3JLwE= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1788345452; c=relaxed/simple; bh=fT7IVu7aFVQfQr/L+icXE7NMgFptEmRr1+y6ErHWrPs=; h=Date:From:To:Cc:Subject:Message-ID:References:MIME-Version: Content-Type:Content-Disposition:In-Reply-To; b=ZIfRpqvZVazCy+z/VeFKkNTgvWGLAWHOzo91Lxlg72jxJqf89tHp6tZUhpap9rDNwFDX13rVnDJ705c13r6mvfrQFPCaZv9/c9EwTN+DICw0JajOI9ZlNBLC86jGD2DoqsDX7Yc+Zkzurb2j7crGnBGJWsdogJO4XuUGmJVv3rw= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=infradead.org; spf=pass smtp.mailfrom=infradead.org; dkim=pass (2048-bit key) header.d=infradead.org header.i=@infradead.org header.b=I6YdpxZW; 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=pass 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="I6YdpxZW" 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=ETO3mB1C7LiuFbXXbTBEqUN6KDHlx2zGjrBCITzqSfg=; b=I6YdpxZWyT2BLy6d+NogBCWz8P 5TYj7OcEWwXxDZ8LCH+W8j9S3167Opp8mWBgcbOQdhUEkNOcvZrsFYF7qN5BVKKFiy6AuBYoBTEjV R2Ec7VIl8NUgUHhzvTFTJwf7t9UIeblpnkKeRzxhOZgZj5cl8MR4qDkuFEqNHyOTqbf9VqCmajW84 +zj+UeduJtJNe6ltU+cLKjAFIKHW3pxd3ttKOPRIql18IOOsGZOllhPGBAm88CWhc0owWUOSvNLnN mJwQF5sb7KH1dWm1WxD8nE1pcMkHNYle75T90Dy4j+cT6EOJCqMduJ8xH+BpIObykKjGUfuKbb7/5 AgVE9rSQ==; 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 1x1iKt-00000006rdc-45P7; Wed, 02 Sep 2026 10:36:56 +0000 Received: by noisy.programming.kicks-ass.net (Postfix, from userid 1000) id 095C8300FB6; Wed, 02 Sep 2026 12:36:54 +0200 (CEST) Date: Wed, 2 Sep 2026 12:36:54 +0200 From: Peter Zijlstra To: Vincent Guittot Cc: Chen Yu , mingo@kernel.org, juri.lelli@redhat.com, dietmar.eggemann@arm.com, rostedt@goodmis.org, bsegall@google.com, mgorman@suse.de, vschneid@redhat.com, kprateek.nayak@amd.com, tj@kernel.org, linux-kernel@vger.kernel.org, chen.yu@linux.dev, tim.c.chen@linux.intel.com Subject: Re: [PATCH 4/4] sched/fair: Rework/fix task_h_load() Message-ID: <20260902103654.GB4121620@noisy.programming.kicks-ass.net> References: <20260828074059.232353141@infradead.org> <20260828075558.660152190@infradead.org> <20260902081301.GS4120091@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: <20260902081301.GS4120091@noisy.programming.kicks-ass.net> On Wed, Sep 02, 2026 at 10:13:01AM +0200, Peter Zijlstra wrote: > Let me go and try and reproduce. Different physical machine.. *splat*, virtual machine it lives. Argh I hate computers. Anyway, confirmed on physical machine that triggered it, the blow seems to cure things. I'll fold it in. --- --- a/kernel/sched/fair.c +++ b/kernel/sched/fair.c @@ -15287,9 +15287,6 @@ static void set_next_task_fair(struct rq weight = __calc_prop_weight(cfs_rq, se, weight); } - for_each_sched_entity_bl(se, cfs_rq) - update_cfs_rq_h_load(group_cfs_rq(se), se, cfs_rq); - if (throttled) task_throttle_setup_work(p); @@ -15309,11 +15306,15 @@ static void set_next_task_fair(struct rq */ list_move(&se->group_node, &rq->cfs_tasks); } - if (!first) - return; WARN_ON_ONCE(se->sched_delayed); + for_each_sched_entity_bl(se, cfs_rq) + update_cfs_rq_h_load(group_cfs_rq(se), se, cfs_rq); + + if (!first) + return; + if (hrtick_enabled_fair(rq)) hrtick_start_fair(rq, p);