From: Tejun Heo <tj@kernel.org>
To: Andrea Righi <arighi@nvidia.com>
Cc: David Vernet <void@manifault.com>,
Changwoo Min <changwoo@igalia.com>,
linux-kernel@vger.kernel.org
Subject: Re: [PATCH] sched_ext: Refresh idle state when kicking CPUs
Date: Thu, 2 Jan 2025 12:33:06 -1000 [thread overview]
Message-ID: <Z3cUIkOkfZ3n-XTz@slm.duckdns.org> (raw)
In-Reply-To: <20250101182449.21517-1-arighi@nvidia.com>
Hello,
On Wed, Jan 01, 2025 at 07:24:49PM +0100, Andrea Righi wrote:
...
> @@ -6104,6 +6117,7 @@ static bool kick_one_cpu(s32 cpu, struct rq *this_rq, unsigned long *pseqs)
> should_wait = true;
> }
>
> + refresh_idle_state_on_kick(rq);
> resched_curr(rq);
I'm not sure this is quite correct. e.g. This can cause multiple
back-to-back busy->busy transitions and can incorrectly assert idle when the
CPU ends up running non-idle tasks afterwards.
When the put_prev/set_next paths were reorganized, we lost the signal on the
CPU re-entering idle from idle. However, that signal is still available if
we hook into idle_class->pick_task(), right? So, if we move
update_idle(true) call there and make sure that we don't generate an event
on busy->busy transitions, we should be able to restore the previous
behavior?
Thanks.
--
tejun
next prev parent reply other threads:[~2025-01-02 22:33 UTC|newest]
Thread overview: 7+ messages / expand[flat|nested] mbox.gz Atom feed top
2025-01-01 18:24 [PATCH] sched_ext: Refresh idle state when kicking CPUs Andrea Righi
2025-01-02 22:33 ` Tejun Heo [this message]
2025-01-03 8:55 ` Andrea Righi
2025-01-03 21:39 ` Tejun Heo
2025-01-04 7:06 ` Andrea Righi
2025-01-06 18:53 ` Tejun Heo
2025-01-08 0:17 ` kernel test robot
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