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From: K Prateek Nayak <kprateek.nayak@amd.com>
To: Peter Zijlstra <peterz@infradead.org>
Cc: Adam Li <adamli@os.amperecomputing.com>, <mingo@redhat.com>,
	<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>, <patches@amperecomputing.com>,
	<cl@linux.com>, <christian.loehle@arm.com>,
	<vineethr@linux.ibm.com>
Subject: Re: [PATCH v2 1/3] sched/fair: Fix warning if NEXT_BUDDY enabled
Date: Fri, 29 Nov 2024 23:23:11 +0530	[thread overview]
Message-ID: <2ab494a6-e5d7-45a9-800a-d104f905f12f@amd.com> (raw)
In-Reply-To: <6683a7dc-b83b-489c-bdfc-ad225ab816c6@amd.com>

On 11/29/2024 11:16 PM, K Prateek Nayak wrote:
> [..snip..]
> newidle balance pulls a delayed entity which goes through the
> check_preempt_wakeup_fair() path in attach_task() and is set as the next
> buddy. On a second thought this is perhaps not required since even if
> this delayed entity is picked, it'll go thorough a full dequeue and the
> clear_buddies() change above should take care of it.

That said, it'll still trigger the following warning in
pick_next_entity():

     /* ->next will never be delayed */
     SCHED_WARN_ON(cfs_rq->next->sched_delayed);

which is also why I added that check in check_preempt_wakeup_fair() :)

-- 
Thanks and Regards,
Prateek


  reply	other threads:[~2024-11-29 17:53 UTC|newest]

Thread overview: 24+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2024-11-27  5:56 [PATCH v2 0/3] sched/fair: Fix NEXT_BUDDY panic and warning Adam Li
2024-11-27  5:56 ` [PATCH v2 1/3] sched/fair: Fix warning if NEXT_BUDDY enabled Adam Li
2024-11-28  7:29   ` K Prateek Nayak
2024-11-29  3:21     ` Adam Li
2024-11-29  4:28       ` K Prateek Nayak
2024-11-29  7:40         ` Adam Li
2024-11-29  8:00           ` K Prateek Nayak
2024-11-29  9:55     ` Peter Zijlstra
2024-11-29 10:15       ` [PATCH] sched/fair: Untangle NEXT_BUDDY and pick_next_task() Peter Zijlstra
2024-11-29 10:18         ` Peter Zijlstra
2024-11-29 10:37           ` Adam Li
2024-11-29 11:45             ` Peter Zijlstra
2024-12-06  6:47         ` Adam Li
2024-12-09 11:00         ` [tip: sched/core] " tip-bot2 for Peter Zijlstra
2024-11-29 17:46       ` [PATCH v2 1/3] sched/fair: Fix warning if NEXT_BUDDY enabled K Prateek Nayak
2024-11-29 17:53         ` K Prateek Nayak [this message]
2024-12-03 16:05     ` Peter Zijlstra
2024-12-03 16:48       ` K Prateek Nayak
2024-12-09 11:00     ` [tip: sched/core] sched/fair: Fix NEXT_BUDDY tip-bot2 for K Prateek Nayak
2024-11-27  5:56 ` [PATCH v2 2/3] sched/fair: Fix panic if pick_eevdf() returns NULL Adam Li
2024-11-29  9:18   ` Peter Zijlstra
2024-11-27  5:56 ` [PATCH v2 3/3] sched/fair: Update comments regarding last and skip buddy Adam Li
2025-03-13  8:30   ` Madadi Vineeth Reddy
2025-03-14  2:53     ` Adam Li

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