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From: Peter Zijlstra <peterz@infradead.org>
To: K Prateek Nayak <kprateek.nayak@amd.com>
Cc: Aaron Lu <ziqianlu@bytedance.com>, Ingo Molnar <mingo@redhat.com>,
	Juri Lelli <juri.lelli@redhat.com>,
	Vincent Guittot <vincent.guittot@linaro.org>,
	Dietmar Eggemann <dietmar.eggemann@arm.com>,
	Steven Rostedt <rostedt@goodmis.org>,
	Ben Segall <bsegall@google.com>, Mel Gorman <mgorman@suse.de>,
	Valentin Schneider <vschneid@redhat.com>,
	Josh Don <joshdon@google.com>,
	linux-kernel@vger.kernel.org
Subject: Re: [PATCH 3/5] sched/fair: Call update_curr() before unthrottling the hierarchy
Date: Mon, 1 Jun 2026 13:27:52 +0200	[thread overview]
Message-ID: <20260601112752.GR3493090@noisy.programming.kicks-ass.net> (raw)
In-Reply-To: <a0a942c4-98e3-4e13-b481-43045641cabe@amd.com>

On Mon, Jun 01, 2026 at 11:20:30AM +0530, K Prateek Nayak wrote:
> Hello Aaron,
> 
> On 6/1/2026 9:22 AM, Aaron Lu wrote:
> >> Since all callers of unthrottle_cfs_rq(), except one, already update the
> >> rq_clock and call rq_clock_start_loop_update(), move the
> >> update_rq_clock() in unthrottle_cfs_rq() to the lonely caller that
> >> doesn't update the rq_clock.
> > 
> > Looks like there is one more path that doesn't have clock updated:
> > cpu_max_write() -> tg_set_bandwidth() -> tg_set_cfs_bandwidth() ->
> > unthrottle_cfs_rq().
> 
> Woops! Completely missed that. Thank you for pointing it out. I'll
> add an update_rq_clock() there too once we grab the rq_lock.


Like this?

--- a/kernel/sched/core.c
+++ b/kernel/sched/core.c
@@ -9830,6 +9830,7 @@ static int tg_set_cfs_bandwidth(struct t
 		struct rq *rq = cfs_rq->rq;
 
 		guard(rq_lock_irq)(rq);
+		update_rq_clock();
 		cfs_rq->runtime_enabled = runtime_enabled;
 		cfs_rq->runtime_remaining = 1;
 

  reply	other threads:[~2026-06-01 11:28 UTC|newest]

Thread overview: 21+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2026-05-28  9:48 [PATCH 0/5] sched/fair: Allow account_cfs_rq_runtime() to throttle current hierarchy K Prateek Nayak
2026-05-28  9:48 ` [PATCH 1/5] sched/fair: Convert cfs bandwidth throttling to use guards K Prateek Nayak
2026-05-28 21:46   ` Benjamin Segall
2026-05-28  9:48 ` [PATCH 2/5] sched/fair: Use throttled_csd_list for local unthrottle K Prateek Nayak
2026-05-28 21:53   ` Benjamin Segall
2026-05-28  9:48 ` [PATCH 3/5] sched/fair: Call update_curr() before unthrottling the hierarchy K Prateek Nayak
2026-05-28 22:03   ` Benjamin Segall
2026-06-01  3:52   ` Aaron Lu
2026-06-01  5:50     ` K Prateek Nayak
2026-06-01 11:27       ` Peter Zijlstra [this message]
2026-06-02  6:33         ` K Prateek Nayak
2026-05-28  9:48 ` [PATCH 4/5] sched/fair: Move the throttled tasks to a local list in tg_unthrottle_up() K Prateek Nayak
2026-05-28 22:14   ` Benjamin Segall
2026-05-28  9:48 ` [PATCH 5/5] sched/fair: Unify cfs_rq throttling via account_cfs_rq_runtime() K Prateek Nayak
2026-05-28 22:44   ` Benjamin Segall
2026-06-01 13:48   ` Peter Zijlstra
2026-06-02  7:01     ` K Prateek Nayak
2026-06-02  8:32       ` Peter Zijlstra
2026-06-02  8:57         ` K Prateek Nayak
2026-05-28 11:45 ` [PATCH 0/5] sched/fair: Allow account_cfs_rq_runtime() to throttle current hierarchy Peter Zijlstra
2026-06-01  6:18 ` Aaron Lu

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