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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: Mon, 6 Jan 2025 08:53:20 -1000	[thread overview]
Message-ID: <Z3wmoFPes_Qb-hTg@slm.duckdns.org> (raw)
In-Reply-To: <Z3jd8ohf_05k1ie3@gpd3>

Hello,

On Sat, Jan 04, 2025 at 08:06:26AM +0100, Andrea Righi wrote:
...
> The issue is that we call ops.update_idle() when a CPU enters or exits
> SCHED_IDLE, whereas it should ideally be called when the CPU transitions
> in/out of the idle state. So perhaps a kick from idle should trigger
> ops.update_idle(cpu, false)? Still, I'm not sure if that would provide any
> benefit... after all, do you see any practical scenarios where having
> unbalanced transitions could be a problem?

If possible, we should keep the calls balanced even if that means a bit of
complications on the core side as these things can become subtle bugs from
BPF scheduler side. And, yeah, I think kicking transitioning the CPU out of
idle makes sense to me.

Thanks.

-- 
tejun

  reply	other threads:[~2025-01-06 18:53 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
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 [this message]
2025-01-08  0:17 ` kernel test robot

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