From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from foss.arm.com (foss.arm.com [217.140.110.172]) by smtp.subspace.kernel.org (Postfix) with ESMTP id 2AD6C227E94 for ; Mon, 10 Mar 2025 10:53:43 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=217.140.110.172 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1741604025; cv=none; b=EMVAzv3g7aOlBEMSZvYxsVQ0X/1pp1alkCtHppuvbNEgoePn8ZNqjBFOqvPt5l7yyToY3qxkU28g1nn1rG/Z5AsuHzipQnvzALQpewDRUWr5VR5qM5cAS469GCxzjZTDwzENArS8p0Zsg2Z09pgqrgvDbfuEhRxQUodjIvNlgto= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1741604025; c=relaxed/simple; bh=kLQPSTKYeEXqLjLThv353A1zrewHsiXzhvlDGG/344Y=; h=Message-ID:Date:MIME-Version:Subject:To:Cc:References:From: In-Reply-To:Content-Type; b=bgbYUnTez5yPj7KGLrxQvnolEye4RGxdcpe4owSJWKv4yhidEJK0jVu6+E3J6kcwg64FXFUIlusljxGJEILCl2QzjGEGLQyh9abU5Zjhi9RZm2DSNWIpz5/nEw7Byyg6hAoSoDvkyM++G5yWCCc427I3E00oBH07RqSABX7U1wA= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=arm.com; spf=pass smtp.mailfrom=arm.com; arc=none smtp.client-ip=217.140.110.172 Authentication-Results: smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=arm.com Authentication-Results: smtp.subspace.kernel.org; spf=pass smtp.mailfrom=arm.com Received: from usa-sjc-imap-foss1.foss.arm.com (unknown [10.121.207.14]) by usa-sjc-mx-foss1.foss.arm.com (Postfix) with ESMTP id D765A153B; Mon, 10 Mar 2025 03:53:54 -0700 (PDT) Received: from [192.168.178.6] (usa-sjc-mx-foss1.foss.arm.com [172.31.20.19]) by usa-sjc-imap-foss1.foss.arm.com (Postfix) with ESMTPSA id 093983F5A1; Mon, 10 Mar 2025 03:53:40 -0700 (PDT) Message-ID: <80c2c9f4-eb84-4a43-9c48-8f776615b45a@arm.com> Date: Mon, 10 Mar 2025 11:53:33 +0100 Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 User-Agent: Mozilla Thunderbird Subject: Re: [PATCH] sched/uclamp: Let each sched_class handle uclamp To: Xuewen Yan Cc: Hongyan Xia , Ingo Molnar , Peter Zijlstra , Juri Lelli , Vincent Guittot , Steven Rostedt , Ben Segall , Mel Gorman , Valentin Schneider , Tejun Heo , David Vernet , Andrea Righi , Changwoo Min , linux-kernel@vger.kernel.org, Xuewen Yan References: <84441660bef0a5e67fd09dc3787178d0276dad31.1740664400.git.hongyan.xia2@arm.com> <4394f2a7-b4e8-419a-a299-f1afa560c944@arm.com> Content-Language: en-US From: Dietmar Eggemann In-Reply-To: Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit On 10/03/2025 03:41, Xuewen Yan wrote: > On Sat, Mar 8, 2025 at 2:32 AM Dietmar Eggemann > wrote: >> >> On 06/03/2025 13:01, Xuewen Yan wrote: >>> On Thu, Mar 6, 2025 at 2:24 AM Dietmar Eggemann >>> wrote: >>>> >>>> On 27/02/2025 14:54, Hongyan Xia wrote: >>>> >>>> [...] >>>> >>>>> diff --git a/kernel/sched/fair.c b/kernel/sched/fair.c >>>>> index 857808da23d8..7e5a653811ad 100644 >>>>> --- a/kernel/sched/fair.c >>>>> +++ b/kernel/sched/fair.c >>>>> @@ -6941,8 +6941,10 @@ enqueue_task_fair(struct rq *rq, struct task_struct *p, int flags) >>>>> * Let's add the task's estimated utilization to the cfs_rq's >>>>> * estimated utilization, before we update schedutil. >>>>> */ >>>>> - if (!(p->se.sched_delayed && (task_on_rq_migrating(p) || (flags & ENQUEUE_RESTORE)))) >>>>> + if (!(p->se.sched_delayed && (task_on_rq_migrating(p) || (flags & ENQUEUE_RESTORE)))) { >>>>> + uclamp_rq_inc(rq, p); >>>>> util_est_enqueue(&rq->cfs, p); >>>>> + } >>>> >>>> So you want to have p uclamp-enqueued so that its uclamp_min value >>>> counts for the cpufreq_update_util()/cfs_rq_util_change() calls later in >>>> enqueue_task_fair? >>>> >>>> if (p->in_iowait) >>>> cpufreq_update_util(rq, SCHED_CPUFREQ_IOWAIT); >>>> >>>> enqueue_entity() -> update_load_avg() -> cfs_rq_util_change() -> >>>> cpufreq_update_util() >>>> >>>> But if you do this before requeue_delayed_entity() (1) you will not >>>> uclamp-enqueue p which got his ->sched_delayed just cleared in (1)? >>>> >>> >>> Could we change to the following: >>> >>> when enqueue: >>> >>> - if (!(p->se.sched_delayed && (task_on_rq_migrating(p) || (flags >>> & ENQUEUE_RESTORE)))) >>> + if (!(p->se.sched_delayed && !(flags & ENQUEUE_DELAYED))) >> >> Why you want to check ENQUEUE_DELAYED as well here? Isn't >> !p->se.sched_delayed implying !ENQUEUE_DELAYED). > > Indeed, the (!(p->se.sched_delayed && !(flags & ENQUEUE_DELAYED))) is equal to > the (!(p->se.sched_delayed && (task_on_rq_migrating(p) || (flags & > ENQUEUE_RESTORE)))). > I just think it might be easier to read using the ENQUEUE_DELAYED flag. > Because we only allow enq the uclamp and util_est when wake up the delayed-task. OK, I see. So that means we would not have to move the uclamp handling into the sched classes necessarily, we could use flags in enqueue_task() as well: -->8-- Subject: [PATCH] Align uclamp and util_est and call before freq update Signed-off-by: Dietmar Eggemann --- kernel/sched/core.c | 14 ++++++++------ kernel/sched/fair.c | 4 ++-- 2 files changed, 10 insertions(+), 8 deletions(-) diff --git a/kernel/sched/core.c b/kernel/sched/core.c index b60916d77482..f833108a3b2d 100644 --- a/kernel/sched/core.c +++ b/kernel/sched/core.c @@ -1747,7 +1747,8 @@ static inline void uclamp_rq_dec_id(struct rq *rq, struct task_struct *p, } } -static inline void uclamp_rq_inc(struct rq *rq, struct task_struct *p) +static inline void uclamp_rq_inc(struct rq *rq, struct task_struct *p, + int flags) { enum uclamp_id clamp_id; @@ -1763,7 +1764,7 @@ static inline void uclamp_rq_inc(struct rq *rq, struct task_struct *p) if (unlikely(!p->sched_class->uclamp_enabled)) return; - if (p->se.sched_delayed) + if (p->se.sched_delayed && !(flags & ENQUEUE_DELAYED)) return; for_each_clamp_id(clamp_id) @@ -2067,12 +2068,13 @@ void enqueue_task(struct rq *rq, struct task_struct *p, int flags) if (!(flags & ENQUEUE_NOCLOCK)) update_rq_clock(rq); - p->sched_class->enqueue_task(rq, p, flags); /* - * Must be after ->enqueue_task() because ENQUEUE_DELAYED can clear - * ->sched_delayed. + * Can be before ->enqueue_task() because uclamp considers the + * ENQUEUE_DELAYED task before its ->sched_delayed gets cleared + * in ->enqueue_task(). */ - uclamp_rq_inc(rq, p); + uclamp_rq_inc(rq, p, flags); + p->sched_class->enqueue_task(rq, p, flags); psi_enqueue(p, flags); diff --git a/kernel/sched/fair.c b/kernel/sched/fair.c index 061a29e88ee2..e26d1dfea601 100644 --- a/kernel/sched/fair.c +++ b/kernel/sched/fair.c @@ -6951,7 +6951,7 @@ enqueue_task_fair(struct rq *rq, struct task_struct *p, int flags) * Let's add the task's estimated utilization to the cfs_rq's * estimated utilization, before we update schedutil. */ - if (!(p->se.sched_delayed && (task_on_rq_migrating(p) || (flags & ENQUEUE_RESTORE)))) + if (!p->se.sched_delayed || (flags & ENQUEUE_DELAYED)) util_est_enqueue(&rq->cfs, p); if (flags & ENQUEUE_DELAYED) { @@ -7193,7 +7193,7 @@ static int dequeue_entities(struct rq *rq, struct sched_entity *se, int flags) */ static bool dequeue_task_fair(struct rq *rq, struct task_struct *p, int flags) { - if (!(p->se.sched_delayed && (task_on_rq_migrating(p) || (flags & DEQUEUE_SAVE)))) + if (!p->se.sched_delayed) util_est_dequeue(&rq->cfs, p); util_est_update(&rq->cfs, p, flags & DEQUEUE_SLEEP); -- 2.34.1