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Date: Thu, 23 Apr 2026 11:57:06 -1000
From: Tejun Heo <tj@kernel.org>
To: Kuba Piecuch <jpiecuch@google.com>
Cc: Andrea Righi <arighi@nvidia.com>, Changwoo Min <changwoo@igalia.com>,
	David Vernet <void@manifault.com>, linux-kernel@vger.kernel.org,
	sched-ext@lists.linux.dev
Subject: Re: SCX_ENQ_IMMED potentially leaving dispatched tasks lingering on
 local DSQs
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In-Reply-To: <DI0SXNWQZSTV.39HPITQGOG1YS@google.com>

Hello,

On Thu, Apr 23, 2026 at 08:03:51PM +0000, Kuba Piecuch wrote:
...
> I don't like the idea of maintaining the separate checks, precisely because
> of how subtle and finnicky they are. I worry that it will be difficult to keep
> all cases covered as the codebase evolves.
> 
> As an optimization, we could skip wakeup_preempt() in local_dsq_post_enq() if
> rq->next_class == &ext_sched_class. That should make the performance impact
> negligible in the common case, WDYT?

Yeah, let's do that. Please send a patch and can you also cc PeterZ?

Thanks.

-- 
tejun