From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from casper.infradead.org (casper.infradead.org [90.155.50.34]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id 5701E361943; Thu, 24 Sep 2026 09:09:14 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=90.155.50.34 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1790240959; cv=none; b=Jg6NA2r8XvTtW6cQhYd2ca7no2T3gDNFpNjnnMYtL38dAJ6Wg02g49NHjyI/QujoOupRcAbceKW1BXzeVBoAS0igZuZK1dqywGULQBlSTPYWGgZgYcum1wVWcodTNAYkGmomEmrFjEtUNXDD/DQ3lSztprVyrZiP4p+TVFIUeM0= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1790240959; c=relaxed/simple; bh=dOsSfragpCZL89liI2A5/mqYVe92z3wf5VnFwhzclkw=; h=Date:From:To:Cc:Subject:Message-ID:References:MIME-Version: Content-Type:Content-Disposition:In-Reply-To; b=mzODQQaMvWAPGlNDu9Mse2k3izEQiPeWhtXBn1nU4ejjo06etnuh3J9SqsZJ79ndPcmmRM6XGhXvtbtYtNKG6+dVeTt7U/eY4J3RenaDawCRzgLj3kpIpfENW1v/TM1Q6jDQL1UIfOHfZfpY+pcQcxbY0EgpPTrYQ8QL5/LelGE= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=infradead.org; spf=pass smtp.mailfrom=infradead.org; dkim=pass (2048-bit key) header.d=infradead.org header.i=@infradead.org header.b=NbY6NG6/; arc=none smtp.client-ip=90.155.50.34 Authentication-Results: smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=infradead.org Authentication-Results: smtp.subspace.kernel.org; spf=pass smtp.mailfrom=infradead.org Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=infradead.org header.i=@infradead.org header.b="NbY6NG6/" DKIM-Signature: v=1; a=rsa-sha256; q=dns/txt; c=relaxed/relaxed; d=infradead.org; s=casper.20170209; h=In-Reply-To:Content-Type:MIME-Version: References:Message-ID:Subject:Cc:To:From:Date:Sender:Reply-To: Content-Transfer-Encoding:Content-ID:Content-Description; bh=RoVa9dxqACSdBBc9RiLcnsqg8L3EHSWBbwPTgAJYlOg=; b=NbY6NG6/v+bC3MuNiZN4cE28va HQc+HJctv4Lhx4+MllJluCtEFC+L4SOCZ8IoUKcGWO6qg+pL+ZR9jqE+vRJsANQaE6yMHrcfeFfn3 0+/tqZ4eO8P54jnE+3OLmug7OLvmb55Ez7GdB+IfRXw34ZIDU0ScBQQawLuZnt/I4VnMmgKxk3aVJ w4qxegA26HWm8n4jdQsyC7yCEuwt9/kJaqoeIKJU74ohigXv+y7WvUfYnjTTRkd80xkkP7qJ5zowL CMFHV6N8ctpfu5cnRfDR9EAN9kcvQVG95gwjLxxa46IltUsnijDBoNtHR/UD5mZ1wtMfPWYJx5FFi xZEZ2o2A==; Received: from 77-249-17-252.cable.dynamic.v4.ziggo.nl ([77.249.17.252] helo=noisy.programming.kicks-ass.net) by casper.infradead.org with esmtpsa (Exim 4.99.1 #2 (Red Hat Linux)) id 1x9fRx-0000000G1zG-270n; Thu, 24 Sep 2026 09:09:05 +0000 Received: by noisy.programming.kicks-ass.net (Postfix, from userid 1000) id 66DDF3006DD; Thu, 24 Sep 2026 11:09:04 +0200 (CEST) Date: Thu, 24 Sep 2026 11:09:04 +0200 From: Peter Zijlstra To: K Prateek Nayak Cc: Andrea Righi , Tejun Heo , David Vernet , Changwoo Min , John Stultz , Ingo Molnar , Juri Lelli , Vincent Guittot , Dietmar Eggemann , Steven Rostedt , Ben Segall , Mel Gorman , Valentin Schneider , Christian Loehle , David Dai , Koba Ko , Aiqun Yu , Shuah Khan , sched-ext@lists.linux.dev, linux-kernel@vger.kernel.org Subject: Re: [PATCHSET v14 sched_ext/for-7.4] sched: Make proxy execution compatible with sched_ext Message-ID: <20260924090904.GJ2009045@noisy.programming.kicks-ass.net> References: <20260922165445.943315-1-arighi@nvidia.com> <20260924075237.GH2009045@noisy.programming.kicks-ass.net> <20260924075925.GE4121620@noisy.programming.kicks-ass.net> <05319013-86e6-4a80-bb8f-385657cee410@amd.com> Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <05319013-86e6-4a80-bb8f-385657cee410@amd.com> On Thu, Sep 24, 2026 at 01:40:27PM +0530, K Prateek Nayak wrote: > On 9/24/2026 1:29 PM, Peter Zijlstra wrote: > >> Almost like switching_to_scx(), except it needs to change ctx->queued in case > >> of p->is_blocked. Hence a new callback ran before sched_change_begin(). > > > > And I wonder, would something like so work? > > > > --- > > diff --git a/kernel/sched/core.c b/kernel/sched/core.c > > index adcc9264c0c6..3e7691d24930 100644 > > --- a/kernel/sched/core.c > > +++ b/kernel/sched/core.c > > @@ -11215,8 +11215,13 @@ void sched_change_end(struct sched_change_ctx *ctx) > > */ > > WARN_ON_ONCE(p->sched_class != ctx->class && !(ctx->flags & ENQUEUE_CLASS)); > > > > - if ((ctx->flags & ENQUEUE_CLASS) && p->sched_class->switching_to) > > - p->sched_class->switching_to(rq, p); > > + if ((ctx->flags & ENQUEUE_CLASS) && p->sched_class->switching_to) { > > + bool block = p->sched_class->switching_to(rq, p); > > + if (block && p->is_blocked) { > > Shouldn't this also check for "ctx->queued"? > > > + block_task(rq, p, READ_ONCE(p->__state)); > > Otherwise we may block an already off rq task. > > > + ctx->queued = false; > > + } > > + } Yes.