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 B8E5F238C06 for ; Fri, 13 Jun 2025 09:43:33 +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=1749807815; cv=none; b=dLcgRCeeJYfca3Ra4rK5lPPOGPqvTsiPg6JeTNMev9HRLaTXBgqPWbHEL2+FDKwhhss+C0/T2gAEvY0/MRouJA7xLW67Z4ImEvTwJ+qbIoU3KVFxDjdbpZ/AqHXqOzV1BKTaa/flfcAMttrWOyA8FvSuRM88vgHooAKbW22wxOg= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1749807815; c=relaxed/simple; bh=KDmI3SzjPp2KgOWUtFfz6WBnZsJ1KnGOl71hkWybfyE=; h=Date:From:To:Cc:Subject:Message-ID:References:MIME-Version: Content-Type:Content-Disposition:In-Reply-To; b=ct5lnc/C+Vup6FvG7I7c6j8mXnAIc6rdTDUpRaWtAZ8lu28fy1aRl66OXocb9D8uDOzTINpex6QFNQKdqwTGglo7cY3sPWoJTVNzfuGNzif9iBlsAthhbkVsD8qBRKcVnrPN6yKwZT3TdLQnvXqWI5h3nd/xSsxcr2yjDDDP5yY= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dmarc=none (p=none dis=none) header.from=infradead.org; spf=none smtp.mailfrom=infradead.org; dkim=pass (2048-bit key) header.d=infradead.org header.i=@infradead.org header.b=adYjx3+i; arc=none smtp.client-ip=90.155.50.34 Authentication-Results: smtp.subspace.kernel.org; dmarc=none (p=none dis=none) header.from=infradead.org Authentication-Results: smtp.subspace.kernel.org; spf=none 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="adYjx3+i" 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=RXBjLERF3nlmhC8SMKLj3/cxfoD2dWEsI3qpLnYVqKY=; b=adYjx3+iU9FSzQn/t8PomDO7Pb PmOJKa+q7gnJrky/9g0qgG52pH0PguGDTzXpv2kHbnoL4ZTc/UhYAHbjgaTXJwgAAYQ/vJdm53AuB oxXwFVUV56p9N725WfTuqdnVRDs2MlqHoF7NdN6be6qpGgXzxobyyBUWtQ8K5Kycpm4066Ui98sjV YEW3aeqADhASvaiJO8oXbnnx9RMev+0IWv3etPZ23oef9kLnU6matICzQARBNid62USHcjNVwmTuj DgpIucvsAiOBk/KhLXQmzeyvYb87NAb+GQY/sxGXX8UNz25WkyGQZ3ohIA1Q0zMasGNe07VQ7GjVb xvj4L8aA==; 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 4.98.2 #2 (Red Hat Linux)) id 1uQ0wa-0000000Cncv-3Yla; Fri, 13 Jun 2025 09:43:28 +0000 Received: by noisy.programming.kicks-ass.net (Postfix, from userid 1000) id 673E730617F; Fri, 13 Jun 2025 11:43:28 +0200 (CEST) Date: Fri, 13 Jun 2025 11:43:28 +0200 From: Peter Zijlstra To: Juri Lelli Cc: mingo@redhat.com, vincent.guittot@linaro.org, dietmar.eggemann@arm.com, rostedt@goodmis.org, bsegall@google.com, mgorman@suse.de, vschneid@redhat.com, clm@meta.com, linux-kernel@vger.kernel.org Subject: Re: [RFC][PATCH 1/5] sched/deadline: Less agressive dl_server handling Message-ID: <20250613094328.GG2278213@noisy.programming.kicks-ass.net> References: <20250520094538.086709102@infradead.org> <20250520101727.507378961@infradead.org> 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: On Tue, Jun 03, 2025 at 06:03:12PM +0200, Juri Lelli wrote: > Hi, > > > @@ -1684,6 +1689,24 @@ void dl_server_stop(struct sched_dl_enti > > dl_se->dl_server_active = 0; > > } > > > > +static bool dl_server_stopped(struct sched_dl_entity *dl_se) > > +{ > > + if (!dl_se->dl_server_active) > > + return false; > > + > > + if (dl_se->dl_server_idle) { > > + __dl_server_stop(dl_se); > > + return true; > > + } > > + > > + dl_se->dl_server_idle = 1; > > + return false; > > +} > > + > > +void dl_server_stop(struct sched_dl_entity *dl_se) > > +{ > > +} > > What if we explicitly set the server to idle (instead of ignoring the > stop) where this gets called in dequeue_entities()? That would break thing; we want to detect if it was ever !idle in the period. > Also, don't we need to actually stop the server if we are changing its > parameters from sched_fair_server_write()? Quite - let me just remove the offending callsites them. Would this explain this massive regression 0day reported here? Seems weird. Anyway, let me go update the patch.