From nobody Sun Feb 8 15:54:13 2026 Received: from galois.linutronix.de (Galois.linutronix.de [193.142.43.55]) (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 C79A41BC2A; Sun, 18 Aug 2024 06:23:14 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=193.142.43.55 ARC-Seal: i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1723962197; cv=none; b=IA3vVDOrAJpCFKdW5Dr6WvvB9/7bIulI/yCHkV0xaZZ/MUEnDirjnNAAzuxEs7GMq/PBS50MjdEqPQji77aV4ERFQy288LK6JPfKfaEX8iaIiWnVpGKqnIrE+zGzoeFxwDvnCbEuMOEFjzm4zDUPqSkyqplnPrdMUGMhcpreQsk= ARC-Message-Signature: i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1723962197; c=relaxed/simple; bh=OfBYAASQdKd5z5FIyGULEmMi5UhJwqnjlHexZYwX4Z0=; h=Date:From:To:Subject:Cc:In-Reply-To:References:MIME-Version: Message-ID:Content-Type; b=NZwgcNdG7RnfCwM92RMn/4J0atMVsALuvPIr0XCkeVKjS3Nxgau98qELeXpk6nj0wUhZoceX5sTzICxGh+jrJ9L0M+2JeGTf5bSilm4csNvFAfvO6xLm71K38gDwyb8ZlWjOzTTaSYcTSSL6BbBw9Jtw1PgoMNXe5E1QZCtB61k= ARC-Authentication-Results: i=1; smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=linutronix.de; spf=pass smtp.mailfrom=linutronix.de; dkim=pass (2048-bit key) header.d=linutronix.de header.i=@linutronix.de header.b=J/n6cKcU; dkim=permerror (0-bit key) header.d=linutronix.de header.i=@linutronix.de header.b=DojfolIV; arc=none smtp.client-ip=193.142.43.55 Authentication-Results: smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=linutronix.de Authentication-Results: smtp.subspace.kernel.org; spf=pass smtp.mailfrom=linutronix.de Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=linutronix.de header.i=@linutronix.de header.b="J/n6cKcU"; dkim=permerror (0-bit key) header.d=linutronix.de header.i=@linutronix.de header.b="DojfolIV" Date: Sun, 18 Aug 2024 06:23:10 -0000 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=linutronix.de; s=2020; t=1723962191; h=from:from:sender:sender:reply-to:reply-to:subject:subject:date:date: message-id:message-id:to:to:cc:cc:mime-version:mime-version: content-type:content-type: content-transfer-encoding:content-transfer-encoding: in-reply-to:in-reply-to:references:references; bh=Uwrt/7oNpPb7VqOXl+yt82A8EoN/JrvDHmEf62b9Y/g=; b=J/n6cKcUV+b0VFI2wWrjQ9+9mIxtk5E8B8BEe5wMagknlj5Jdfcw+w28KnPANZzpg0fOnV v+CTglnyGcbIldzwX+QShsRqWU6kt3m18MpxVDvQkCSj0Vh4ZZNrtS6OV+kYqdipqyTRMU ffvOq403SUPzMXDaPgkn/g1IoHv2k2jZk0O/U0poFXjfLRRK8Yz/pxhnjL1jshMsY+exXV pj3za72rBrsx2lfHAbzqo8gEvRs8fv9icruiGc+8UwJZi4BEk2OdyTz2XMZSnrfISd91of aegHxK+9nr193c9E1GMFWOcukb4uQrvUYgytCSDL+ny8Ppq8mW/2Y8XuDhIA9A== DKIM-Signature: v=1; a=ed25519-sha256; c=relaxed/relaxed; d=linutronix.de; s=2020e; t=1723962191; h=from:from:sender:sender:reply-to:reply-to:subject:subject:date:date: message-id:message-id:to:to:cc:cc:mime-version:mime-version: content-type:content-type: content-transfer-encoding:content-transfer-encoding: in-reply-to:in-reply-to:references:references; bh=Uwrt/7oNpPb7VqOXl+yt82A8EoN/JrvDHmEf62b9Y/g=; b=DojfolIVrJiZankJPA47t8hUC5fbpSqYvAxAGeTGLp/Tthb3EclEUQFRL/qcpdgdaUZCJ0 AIwrXs5rFGk05uBg== From: "tip-bot2 for Peter Zijlstra" Sender: tip-bot2@linutronix.de Reply-to: linux-kernel@vger.kernel.org To: linux-tip-commits@vger.kernel.org Subject: [tip: sched/core] sched/fair: Re-organize dequeue_task_fair() Cc: "Peter Zijlstra (Intel)" , Valentin Schneider , x86@kernel.org, linux-kernel@vger.kernel.org In-Reply-To: <20240727105028.977256873@infradead.org> References: <20240727105028.977256873@infradead.org> Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Message-ID: <172396219075.2215.11010708052044372414.tip-bot2@tip-bot2> Robot-ID: Robot-Unsubscribe: Contact to get blacklisted from these emails Precedence: bulk Content-Type: text/plain; charset="utf-8" Content-Transfer-Encoding: quoted-printable The following commit has been merged into the sched/core branch of tip: Commit-ID: fab4a808ba9fb59b691d7096eed9b1494812ffd6 Gitweb: https://git.kernel.org/tip/fab4a808ba9fb59b691d7096eed9b1494= 812ffd6 Author: Peter Zijlstra AuthorDate: Wed, 03 Apr 2024 09:50:41 +02:00 Committer: Peter Zijlstra CommitterDate: Sat, 17 Aug 2024 11:06:41 +02:00 sched/fair: Re-organize dequeue_task_fair() Working towards delaying dequeue, notably also inside the hierachy, rework dequeue_task_fair() such that it can 'resume' an interrupted hierarchy walk. Signed-off-by: Peter Zijlstra (Intel) Reviewed-by: Valentin Schneider Tested-by: Valentin Schneider Link: https://lkml.kernel.org/r/20240727105028.977256873@infradead.org --- kernel/sched/fair.c | 62 +++++++++++++++++++++++++++++--------------- 1 file changed, 41 insertions(+), 21 deletions(-) diff --git a/kernel/sched/fair.c b/kernel/sched/fair.c index 03f76b3..59b00d7 100644 --- a/kernel/sched/fair.c +++ b/kernel/sched/fair.c @@ -6861,34 +6861,43 @@ enqueue_throttle: static void set_next_buddy(struct sched_entity *se); =20 /* - * The dequeue_task method is called before nr_running is - * decreased. We remove the task from the rbtree and - * update the fair scheduling stats: + * Basically dequeue_task_fair(), except it can deal with dequeue_entity() + * failing half-way through and resume the dequeue later. + * + * Returns: + * -1 - dequeue delayed + * 0 - dequeue throttled + * 1 - dequeue complete */ -static bool dequeue_task_fair(struct rq *rq, struct task_struct *p, int fl= ags) +static int dequeue_entities(struct rq *rq, struct sched_entity *se, int fl= ags) { - struct cfs_rq *cfs_rq; - struct sched_entity *se =3D &p->se; - int task_sleep =3D flags & DEQUEUE_SLEEP; - int idle_h_nr_running =3D task_has_idle_policy(p); bool was_sched_idle =3D sched_idle_rq(rq); int rq_h_nr_running =3D rq->cfs.h_nr_running; + bool task_sleep =3D flags & DEQUEUE_SLEEP; + struct task_struct *p =3D NULL; + int idle_h_nr_running =3D 0; + int h_nr_running =3D 0; + struct cfs_rq *cfs_rq; =20 - util_est_dequeue(&rq->cfs, p); + if (entity_is_task(se)) { + p =3D task_of(se); + h_nr_running =3D 1; + idle_h_nr_running =3D task_has_idle_policy(p); + } =20 for_each_sched_entity(se) { cfs_rq =3D cfs_rq_of(se); dequeue_entity(cfs_rq, se, flags); =20 - cfs_rq->h_nr_running--; + cfs_rq->h_nr_running -=3D h_nr_running; cfs_rq->idle_h_nr_running -=3D idle_h_nr_running; =20 if (cfs_rq_is_idle(cfs_rq)) - idle_h_nr_running =3D 1; + idle_h_nr_running =3D h_nr_running; =20 /* end evaluation on encountering a throttled cfs_rq */ if (cfs_rq_throttled(cfs_rq)) - goto dequeue_throttle; + return 0; =20 /* Don't dequeue parent if it has other entities besides us */ if (cfs_rq->load.weight) { @@ -6912,20 +6921,18 @@ static bool dequeue_task_fair(struct rq *rq, struct= task_struct *p, int flags) se_update_runnable(se); update_cfs_group(se); =20 - cfs_rq->h_nr_running--; + cfs_rq->h_nr_running -=3D h_nr_running; cfs_rq->idle_h_nr_running -=3D idle_h_nr_running; =20 if (cfs_rq_is_idle(cfs_rq)) - idle_h_nr_running =3D 1; + idle_h_nr_running =3D h_nr_running; =20 /* end evaluation on encountering a throttled cfs_rq */ if (cfs_rq_throttled(cfs_rq)) - goto dequeue_throttle; - + return 0; } =20 - /* At this point se is NULL and we are at root level*/ - sub_nr_running(rq, 1); + sub_nr_running(rq, h_nr_running); =20 if (rq_h_nr_running && !rq->cfs.h_nr_running) dl_server_stop(&rq->fair_server); @@ -6934,10 +6941,23 @@ static bool dequeue_task_fair(struct rq *rq, struct= task_struct *p, int flags) if (unlikely(!was_sched_idle && sched_idle_rq(rq))) rq->next_balance =3D jiffies; =20 -dequeue_throttle: - util_est_update(&rq->cfs, p, task_sleep); - hrtick_update(rq); + return 1; +} + +/* + * The dequeue_task method is called before nr_running is + * decreased. We remove the task from the rbtree and + * update the fair scheduling stats: + */ +static bool dequeue_task_fair(struct rq *rq, struct task_struct *p, int fl= ags) +{ + util_est_dequeue(&rq->cfs, p); + + if (dequeue_entities(rq, &p->se, flags) < 0) + return false; =20 + util_est_update(&rq->cfs, p, flags & DEQUEUE_SLEEP); + hrtick_update(rq); return true; }