From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from out-186.mta0.migadu.com (out-186.mta0.migadu.com [91.218.175.186]) (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 6BD702DCBE7 for ; Fri, 23 May 2025 02:44:08 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=91.218.175.186 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1747968250; cv=none; b=a9hqWSK6CJ3A273s524Y1897HiCDF/TFO4qJa72b0rHNA067PDJjpsJzh41enb6VZ9Km18JYuLdg9ViNuG5RcRMzWllTuSQnNW2YLNfnceEG9anA2IAURP0Gd7QBfcXIMbjR4h9ZWI9/o1idYiZWRrDqznhplE9GoXEbmQWElsM= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1747968250; c=relaxed/simple; bh=pouU501kHvpahr97lsZlPtLEro1NJIHDxG81yNKE250=; h=Message-ID:Date:MIME-Version:Subject:To:Cc:References:From: In-Reply-To:Content-Type; b=ndOs3K/D/c2zC76WFCd1uhSERZcoOkWqPAApwO03y6ssaLCJVhBs1Q3QszuZHyadUJszfxsPjYeVlpsC7Tmh2Kh3b3Nc6nqf3v/M3BLwgOY8AIpPcbLML6T6rPzutyCshmjAY3ARommJQrVQeWvGSswsNoRCT73S15L4H47G4Ss= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=linux.dev; spf=pass smtp.mailfrom=linux.dev; dkim=pass (1024-bit key) header.d=linux.dev header.i=@linux.dev header.b=BIfRqsWi; arc=none smtp.client-ip=91.218.175.186 Authentication-Results: smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=linux.dev Authentication-Results: smtp.subspace.kernel.org; spf=pass smtp.mailfrom=linux.dev Authentication-Results: smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=linux.dev header.i=@linux.dev header.b="BIfRqsWi" Message-ID: <63237b23-ae10-45f9-abdd-8ea4adb4d15e@linux.dev> DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=linux.dev; s=key1; t=1747968244; h=from:from: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=Hv/tjh7l4P0EOqRs5walua65leLEpaVzh6pI7mbZFig=; b=BIfRqsWirp310zW/lvG5k6NJ0aJLi+YdxKPpAlxxShgX1MaMdzNl1yDxhqoNLlnTgrCl5P MojCyHiwJyhzm0wmtx/Q0kfI1UcLm/MSdGKI1f6ED+PTvhpOuoDrtiUGEw12/S6MYs0WGb GGHoqXVgYdPEkdnD7lKmgYiOxu6t+pM= Date: Fri, 23 May 2025 10:43:53 +0800 Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Subject: Re: [PATCH 4/7] sched/fair: Take care of group/affinity/sched_class change for throttled task To: Aaron Lu , Valentin Schneider , Ben Segall , K Prateek Nayak , Peter Zijlstra , Josh Don , Ingo Molnar , Vincent Guittot , Xi Wang Cc: linux-kernel@vger.kernel.org, Juri Lelli , Dietmar Eggemann , Steven Rostedt , Mel Gorman , Chuyi Zhou , Jan Kiszka , Florian Bezdeka References: <20250520104110.3673059-1-ziqianlu@bytedance.com> <20250520104110.3673059-5-ziqianlu@bytedance.com> X-Report-Abuse: Please report any abuse attempt to abuse@migadu.com and include these headers. From: Chengming Zhou In-Reply-To: <20250520104110.3673059-5-ziqianlu@bytedance.com> Content-Type: text/plain; charset=UTF-8; format=flowed Content-Transfer-Encoding: 7bit X-Migadu-Flow: FLOW_OUT On 2025/5/20 18:41, Aaron Lu wrote: > On task group change, for tasks whose on_rq equals to TASK_ON_RQ_QUEUED, > core will dequeue it and then requeued it. > > The throttled task is still considered as queued by core because p->on_rq > is still set so core will dequeue it, but since the task is already > dequeued on throttle in fair, handle this case properly. > > Affinity and sched class change is similar. How about setting p->on_rq to 0 when throttled? which is the fact that the task is not on cfs queue anymore, does this method cause any problem? Thanks! > > Signed-off-by: Aaron Lu > --- > kernel/sched/fair.c | 24 ++++++++++++++++++++++++ > 1 file changed, 24 insertions(+) > > diff --git a/kernel/sched/fair.c b/kernel/sched/fair.c > index 74bc320cbc238..4c66fd8d24389 100644 > --- a/kernel/sched/fair.c > +++ b/kernel/sched/fair.c > @@ -5866,6 +5866,10 @@ static void throttle_cfs_rq_work(struct callback_head *work) > update_rq_clock(rq); > WARN_ON_ONCE(!list_empty(&p->throttle_node)); > dequeue_task_fair(rq, p, DEQUEUE_SLEEP | DEQUEUE_SPECIAL); > + /* > + * Must not add it to limbo list before dequeue or dequeue will > + * mistakenly regard this task as an already throttled one. > + */ > list_add(&p->throttle_node, &cfs_rq->throttled_limbo_list); > resched_curr(rq); > } > @@ -5881,6 +5885,20 @@ void init_cfs_throttle_work(struct task_struct *p) > INIT_LIST_HEAD(&p->throttle_node); > } > > +static void dequeue_throttled_task(struct task_struct *p, int flags) > +{ > + /* > + * Task is throttled and someone wants to dequeue it again: > + * it must be sched/core when core needs to do things like > + * task affinity change, task group change, task sched class > + * change etc. > + */ > + WARN_ON_ONCE(p->se.on_rq); > + WARN_ON_ONCE(flags & DEQUEUE_SLEEP); > + > + list_del_init(&p->throttle_node); > +} > + > static void enqueue_task_fair(struct rq *rq, struct task_struct *p, int flags); > static int tg_unthrottle_up(struct task_group *tg, void *data) > { > @@ -6834,6 +6852,7 @@ static inline void sync_throttle(struct task_group *tg, int cpu) {} > static __always_inline void return_cfs_rq_runtime(struct cfs_rq *cfs_rq) {} > static void task_throttle_setup_work(struct task_struct *p) {} > static bool task_is_throttled(struct task_struct *p) { return false; } > +static void dequeue_throttled_task(struct task_struct *p, int flags) {} > > static inline int cfs_rq_throttled(struct cfs_rq *cfs_rq) > { > @@ -7281,6 +7300,11 @@ 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 (unlikely(task_is_throttled(p))) { > + dequeue_throttled_task(p, flags); > + return true; > + } > + > if (!(p->se.sched_delayed && (task_on_rq_migrating(p) || (flags & DEQUEUE_SAVE)))) > util_est_dequeue(&rq->cfs, p); >