From nobody Mon Feb 9 10:26:04 2026 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 5FE8135503A for ; Fri, 30 Jan 2026 09:47:26 +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=1769766448; cv=none; b=DDdXkhJr0qn9OkSTbQ+N0eHOBi8PivEKMnJ1OhJ/YCzGarygkSc5PJznWlPSdaWAZvoJhB7wVNZn7DpnzZKcVfkLBaqLv7v7TSurIQpUjpT6mUolCiTdA1PmswPHHiJkPAOqgV8UfAffjSbRnE/2B037Q0NuwxOIzdKVY/fJK1Y= ARC-Message-Signature: i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1769766448; c=relaxed/simple; bh=CUzSYwXtEn6bKJhYuTm2YTqKJiPH8OF3mreBceKxDwk=; h=Message-ID:Date:From:To:Cc:Subject:References:MIME-Version: Content-Type; b=oERFj2/iHQlXYk0zKvcuufnP2h79CS8sanWv9gLnxjA2c50XSwA6aFZMeXofgRJLbwwzjK7nzdAzz7rjtECXJKUKWFn+18EmIE3FMr6kVWgmJKt5Qtjafx+fIAE3kFsyFxRizcwrckO2wB/x25RB+Sp/Nk2GW3LPtpe8HPvQxwA= 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=gVfs2bjF; 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="gVfs2bjF" DKIM-Signature: v=1; a=rsa-sha256; q=dns/txt; c=relaxed/relaxed; d=infradead.org; s=casper.20170209; h=Content-Type:MIME-Version:References: Subject:Cc:To:From:Date:Message-ID:Sender:Reply-To:Content-Transfer-Encoding: Content-ID:Content-Description:In-Reply-To; bh=sfP2nSjjOinSs1YfVph5mDoqs4X7R7bDhOi26++MamM=; b=gVfs2bjFYOkvQPfbTI5V8DJJ1u MMiOQKUa+yKrBRmyMDKCgn2fIMzumk4T638aF9YiX+7Gru2rdFLR7WReXZTvyA4zTZnh6Zf2Er3gT gOX3PygO2SowJb65n8T6GjZECnWNdqgKky/AEHmILrMV58cKm3aAhexYsJPfUfqhnkF9JRtAYmmn2 frv96KVdwHdNl0+Hptc+etBYFF6eQD1lQ/J2mYnyrVx6A5u5RXccFbpQMvefttu+ZfA6SSFjp2QbD MC0qZkL74ZF79/E+tHiDlw26dQgdGv9RNos17Xq17JlYguym0PVd3aBHlZChNGYQKS6IzL5fFZUP5 Kd/PxZig==; 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 4.98.2 #2 (Red Hat Linux)) id 1vll5n-0000000BzUB-1bs3; Fri, 30 Jan 2026 09:47:07 +0000 Received: by noisy.programming.kicks-ass.net (Postfix, from userid 0) id 2CAE1303320; Fri, 30 Jan 2026 10:47:06 +0100 (CET) Message-ID: <20260130094607.945348633@infradead.org> User-Agent: quilt/0.68 Date: Fri, 30 Jan 2026 10:34:40 +0100 From: Peter Zijlstra To: mingo@kernel.org Cc: peterz@infradead.org, juri.lelli@redhat.com, vincent.guittot@linaro.org, dietmar.eggemann@arm.com, rostedt@goodmis.org, bsegall@google.com, mgorman@suse.de, vschneid@redhat.com, linux-kernel@vger.kernel.org, wangtao554@huawei.com, quzicheng@huawei.com, kprateek.nayak@amd.com, wuyun.abel@bytedance.com, dsmythies@telus.net Subject: [PATCH 1/4] sched/fair: Only set slice protection at pick time References: <20260130093439.803225718@infradead.org> Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Transfer-Encoding: quoted-printable Content-Type: text/plain; charset="utf-8" We should not (re)set slice protection in the sched_change pattern which calls put_prev_task() / set_next_task(). Signed-off-by: Peter Zijlstra (Intel) Reviewed-by: Vincent Guittot --- kernel/sched/fair.c | 11 ++++++----- 1 file changed, 6 insertions(+), 5 deletions(-) --- a/kernel/sched/fair.c +++ b/kernel/sched/fair.c @@ -5420,7 +5420,7 @@ dequeue_entity(struct cfs_rq *cfs_rq, st } =20 static void -set_next_entity(struct cfs_rq *cfs_rq, struct sched_entity *se) +set_next_entity(struct cfs_rq *cfs_rq, struct sched_entity *se, bool first) { clear_buddies(cfs_rq, se); =20 @@ -5435,7 +5435,8 @@ set_next_entity(struct cfs_rq *cfs_rq, s __dequeue_entity(cfs_rq, se); update_load_avg(cfs_rq, se, UPDATE_TG); =20 - set_protect_slice(cfs_rq, se); + if (first) + set_protect_slice(cfs_rq, se); } =20 update_stats_curr_start(cfs_rq, se); @@ -8958,13 +8959,13 @@ pick_next_task_fair(struct rq *rq, struc pse =3D parent_entity(pse); } if (se_depth >=3D pse_depth) { - set_next_entity(cfs_rq_of(se), se); + set_next_entity(cfs_rq_of(se), se, true); se =3D parent_entity(se); } } =20 put_prev_entity(cfs_rq, pse); - set_next_entity(cfs_rq, se); + set_next_entity(cfs_rq, se, true); =20 __set_next_task_fair(rq, p, true); } @@ -13578,7 +13579,7 @@ static void set_next_task_fair(struct rq for_each_sched_entity(se) { struct cfs_rq *cfs_rq =3D cfs_rq_of(se); =20 - set_next_entity(cfs_rq, se); + set_next_entity(cfs_rq, se, first); /* ensure bandwidth has been allocated on our new cfs_rq */ account_cfs_rq_runtime(cfs_rq, 0); }