From nobody Mon Nov 25 04:46:02 2024 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 DEEBC213ECB for ; Wed, 30 Oct 2024 15:25:52 +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=1730301955; cv=none; b=Tn0wsrneLRcQjAN1WE5aAqjB3Hr4pYB9weoyflPi6jylkg6iKW2rYwcRIruxLVDZ1EVyJsXyZ9dfahVNApQkC/a3JdGd5z+7Rj7WkrJOl/cd+HEKtpas9EuRcXYO6nJDuFW72/mI3SnJT+i/h5BIpp3dXiIha3FD1Y/W+fZJ080= ARC-Message-Signature: i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1730301955; c=relaxed/simple; bh=8E32x75lCrtV/w1t1rzOYa0pZAKOafPl72BulaYj7SA=; h=Message-Id:Date:From:To:Cc:Subject:References:MIME-Version: Content-Type; b=gbEdd2Lb9wfGqMoGN+pOC4Vba8O7ZWVnWGHMhrHpbw5t+TwLS5yX4O7j5NX9cgVTEcLqKq/9WybVAXXMjjisc5EMr8abdPYQsjjn1a4vCoj1x4sdbsSD4blU+ML+yBkrXmpEY8c4sQEaXpc7vU4jxlYfVSbziWx6Gbzvdu5CDsw= ARC-Authentication-Results: i=1; smtp.subspace.kernel.org; dmarc=none (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=lPjADyxu; arc=none smtp.client-ip=90.155.92.199 Authentication-Results: smtp.subspace.kernel.org; dmarc=none (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="lPjADyxu" DKIM-Signature: v=1; a=rsa-sha256; q=dns/txt; c=relaxed/relaxed; d=infradead.org; s=desiato.20200630; 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=k7Ui+RJB68mM8gJ9CNv96KrJtDsj2TyL1J3cQNlTEpk=; b=lPjADyxuluDRY7Hox/Zdyj1fje 24XclypEXGxgngZvduw9Dh/NMlnucbZvJh2MlMi3QpXve6nzNUJJmbkDRK/tM6lQGxRBGZoM3/eS0 gUmat7ExuHZves7rjUzDKBneNvxdWMF0Eehhcv5nJYg/eecRWOiYZxymxA32nh3KH+6y58iUFv92f 0ojSDRHcCcs/wunUbetx2L5e2Jc3w3sL9BIhNS6q0EkKcipm5dCnWK2GQqGV66eWG1atAoCr4PMp6 mNrLjnH41TSKC6D8JINIWaED/hzro5mlA8q4dQm6Hv9G/zYcAOHoYhNmVP9WkaWlH1OYKUfJvVBhT K8tBmD5w==; Received: from j130084.upc-j.chello.nl ([24.132.130.84] helo=noisy.programming.kicks-ass.net) by desiato.infradead.org with esmtpsa (Exim 4.98 #2 (Red Hat Linux)) id 1t6AZt-0000000AI2E-3UAk; Wed, 30 Oct 2024 15:25:46 +0000 Received: by noisy.programming.kicks-ass.net (Postfix, from userid 0) id 0311930625D; Wed, 30 Oct 2024 16:25:43 +0100 (CET) Message-Id: <20241030152142.928034708@infradead.org> User-Agent: quilt/0.65 Date: Wed, 30 Oct 2024 16:13:01 +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, tj@kernel.org, void@manifault.com, linux-kernel@vger.kernel.org Subject: [RFC][PATCH 6/6] sched: Cleanup sched_delayed handling for class switches References: <20241030151255.300069509@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" Use the new sched_class::switching_from() method to dequeue delayed tasks before switching to another class. Signed-off-by: Peter Zijlstra (Intel) --- kernel/sched/core.c | 12 ++++++++---- kernel/sched/ext.c | 12 ++++-------- kernel/sched/fair.c | 7 +++++++ kernel/sched/syscalls.c | 3 --- 4 files changed, 19 insertions(+), 15 deletions(-) --- a/kernel/sched/core.c +++ b/kernel/sched/core.c @@ -7139,9 +7139,6 @@ void rt_mutex_setprio(struct task_struct if (prev_class !=3D next_class) queue_flag |=3D DEQUEUE_CLASS; =20 - if (prev_class !=3D next_class && p->se.sched_delayed) - dequeue_task(rq, p, DEQUEUE_SLEEP | DEQUEUE_DELAYED | DEQUEUE_NOCLOCK); - scoped_guard (sched_change, p, queue_flag) { /* * Boosting condition are: @@ -10530,8 +10527,15 @@ struct sched_change_ctx sched_change_beg =20 lockdep_assert_rq_held(rq); =20 - if ((flags & DEQUEUE_CLASS) && p->sched_class->switching_from) + if ((flags & DEQUEUE_CLASS) && p->sched_class->switching_from) { + /* + * switching_from_fair() assumes CLASS implies NOCLOCK; fixing + * this assumption would mean switching_from() would need to be + * able to change flags. + */ + SCHED_WARN_ON(!(flags & DEQUEUE_NOCLOCK)); p->sched_class->switching_from(rq, p, flags); + } =20 struct sched_change_ctx ctx =3D { .p =3D p, --- a/kernel/sched/ext.c +++ b/kernel/sched/ext.c @@ -4485,7 +4485,7 @@ static void scx_ops_disable_workfn(struc =20 scx_task_iter_start(&sti); while ((p =3D scx_task_iter_next_locked(&sti))) { - unsigned int queue_flags =3D DEQUEUE_SAVE | DEQUEUE_MOVE; + unsigned int queue_flags =3D DEQUEUE_SAVE | DEQUEUE_MOVE | DEQUEUE_NOCLO= CK; const struct sched_class *old_class =3D p->sched_class; const struct sched_class *new_class =3D __setscheduler_class(p->policy, p->prio); @@ -4493,9 +4493,7 @@ static void scx_ops_disable_workfn(struc if (old_class !=3D new_class) queue_flags |=3D DEQUEUE_CLASS; =20 - if (old_class !=3D new_class && p->se.sched_delayed) - dequeue_task(task_rq(p), p, DEQUEUE_SLEEP | DEQUEUE_DELAYED); - + update_rq_clock(task_rq(p)); scoped_guard (sched_change, p, queue_flags) { p->sched_class =3D new_class; } @@ -5202,7 +5200,7 @@ static int scx_ops_enable(struct sched_e percpu_down_write(&scx_fork_rwsem); scx_task_iter_start(&sti); while ((p =3D scx_task_iter_next_locked(&sti))) { - unsigned int queue_flags =3D DEQUEUE_SAVE | DEQUEUE_MOVE; + unsigned int queue_flags =3D DEQUEUE_SAVE | DEQUEUE_MOVE | DEQUEUE_NOCLO= CK; const struct sched_class *old_class =3D p->sched_class; const struct sched_class *new_class =3D __setscheduler_class(p->policy, p->prio); @@ -5210,9 +5208,7 @@ static int scx_ops_enable(struct sched_e if (old_class !=3D new_class) queue_flags |=3D DEQUEUE_CLASS; =20 - if (old_class !=3D new_class && p->se.sched_delayed) - dequeue_task(task_rq(p), p, DEQUEUE_SLEEP | DEQUEUE_DELAYED); - + update_rq_clock(task_rq(p)); scoped_guard (sched_change, p, DEQUEUE_SAVE | DEQUEUE_MOVE) { p->scx.slice =3D SCX_SLICE_DFL; p->sched_class =3D new_class; --- a/kernel/sched/fair.c +++ b/kernel/sched/fair.c @@ -13175,6 +13175,12 @@ static void attach_task_cfs_rq(struct ta attach_entity_cfs_rq(se); } =20 +static void switching_from_fair(struct rq *rq, struct task_struct *p, int = flags) +{ + if ((flags & DEQUEUE_CLASS) && p->se.sched_delayed) + dequeue_task(rq, p, DEQUEUE_SLEEP | DEQUEUE_DELAYED | DEQUEUE_NOCLOCK); +} + static void switched_from_fair(struct rq *rq, struct task_struct *p, int f= lags) { detach_task_cfs_rq(p); @@ -13592,6 +13598,7 @@ DEFINE_SCHED_CLASS(fair) =3D { =20 .reweight_task =3D reweight_task_fair, .prio_changed =3D prio_changed_fair, + .switching_from =3D switching_from_fair, .switched_from =3D switched_from_fair, .switched_to =3D switched_to_fair, =20 --- a/kernel/sched/syscalls.c +++ b/kernel/sched/syscalls.c @@ -701,9 +701,6 @@ int __sched_setscheduler(struct task_str if (prev_class !=3D next_class) queue_flags |=3D DEQUEUE_CLASS; =20 - if (prev_class !=3D next_class && p->se.sched_delayed) - dequeue_task(rq, p, DEQUEUE_SLEEP | DEQUEUE_DELAYED | DEQUEUE_NOCLOCK); - scoped_guard (sched_change, p, queue_flags) { =20 if (!(attr->sched_flags & SCHED_FLAG_KEEP_PARAMS)) {