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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>,
	Joel Fernandes <joelagnelf@nvidia.com>,
	linux-kernel@vger.kernel.org
Subject: Re: [PATCH] sched_ext: Fix missing rq lock in scx_bpf_cpuperf_set()
Date: Thu, 27 Mar 2025 07:19:03 -1000	[thread overview]
Message-ID: <Z-WIh6obKP-ygcsP@slm.duckdns.org> (raw)
In-Reply-To: <Z-WHnYrNHHYx3lpa@gpd3>

Hello,

On Thu, Mar 27, 2025 at 06:15:09PM +0100, Andrea Righi wrote:
> > If we don't want to do locked rq tracking, we can always use
> > schedule_deferred() when any rq is locked too. That's a bit more expensive
> > tho.
> 
> Yeah, I'm a bit worried that locked rq tracking might introduce overhead to
> all the scx callbacks, just to address this issue.

All operaitons are already wrapped with SCX_CALL_OP() and updating per-cpu
state (kf flags). It's unlikely that another percpu variable update is going
to be noticeable.

Thanks.

-- 
tejun

  reply	other threads:[~2025-03-27 17:19 UTC|newest]

Thread overview: 8+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2025-03-25 14:00 [PATCH] sched_ext: Fix missing rq lock in scx_bpf_cpuperf_set() Andrea Righi
2025-03-27  0:24 ` Tejun Heo
2025-03-27  7:56   ` Andrea Righi
2025-03-27  9:53     ` Andrea Righi
2025-03-27 17:09       ` Tejun Heo
2025-03-27 17:15         ` Andrea Righi
2025-03-27 17:19           ` Tejun Heo [this message]
2025-03-27 17:27             ` Andrea Righi

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