linux-kernel - Re: [PATCH v5] sched/stats: Fix rt/dl task's sched latency statistics error in sched_stat

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Message-ID: <9ce7c466-ce9d-4673-b89a-d3244226dbde@redhat.com>
Date: Fri, 12 Jan 2024 08:39:19 +0100
From: Daniel Bristot de Oliveira <bristot@...hat.com>
To: Junwen Wu <wudaemon@....com>, mingo@...hat.com, peterz@...radead.org,
 juri.lelli@...hat.com
Cc: mgorman@...e.de, vschneid@...hat.com, linux-kernel@...r.kernel.org,
 laoar.shao@...il.com, vincent.guittot@...aro.org, dietmar.eggemann@....com,
 rostedt@...dmis.org, bsegall@...gle.com
Subject: Re: [PATCH v5] sched/stats: Fix rt/dl task's sched latency statistics
 error in sched_stat_wait tracepoint

On 1/11/24 16:01, Junwen Wu wrote:
> The sched_stat_wait tracepoint is showing unreasonably long
> latencies for real-time tasks. For example:
> 
> sched_stat_wait: comm=rcu_preempt pid=14 delay=4936139545261 [ns]
> 
> This error happens when the rt task balances off the source CPU because
> the dequeue operation is not updating the sched_statistics. So, follow
> update_stats_wait_end_fair() and update the stats. Do the same for
> SCHED_DEADLINE.
> 
> Fixes: 57a5c2dafca8 ("sched/rt: Support schedstats for RT sched class")
> Fixes: b5eb4a5f6521 ("sched/dl: Support schedstats for deadline sched class")

Reviewed-by: Daniel Bristot de Oliveira <bristot@...nel.org>

Thanks
-- Daniel