From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from desiato.infradead.org (desiato.infradead.org [90.155.92.199]) (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 618893BA22E for ; Fri, 26 Jun 2026 08:09:07 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=90.155.92.199 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1782461350; cv=none; b=mvIVvtE9M7hVq2o0TtqjYdAD1YBdnd1ktzq8nfv+ZVVOpVDHau96ok9Tgv+fv8DHlEgO4nCLnEj0T42glc8JkoyBj+ptJkeCV3cCRi7f4KMUUJ1WlM+NXkZN9HTxxhDCP9T3WUa22H0I3j+mPrCD9PXupDafjdQqOxQGufjQisk= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1782461350; c=relaxed/simple; bh=HnwerLCmdF+b7wt317DOuOGSRZ8pkTlDSpcWOd+EK80=; h=Date:From:To:Cc:Subject:Message-ID:References:MIME-Version: Content-Type:Content-Disposition:In-Reply-To; b=lbxRd21Targn7Olst+3tXdXyGNvcN5fFK3zL4Ih3hgmbyR0nGoRA3E2Sj9CsuWhJrHz/mCpxvVCg6vweCAtONhSkGML62Teu90uQn7VKEUpZ7CFwyZE35o07U38HKx2BF4U8wh7PDe6qB8yTHZ9dIbCXv82/U8qW8+1af7cqxDI= 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=IBElj6Uf; arc=none smtp.client-ip=90.155.92.199 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="IBElj6Uf" DKIM-Signature: v=1; a=rsa-sha256; q=dns/txt; c=relaxed/relaxed; d=infradead.org; s=desiato.20200630; 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=itsdnZm9N4YIy1bhTiVNXAdcw0votSlcMomeOnv2IsA=; b=IBElj6UfVIxpZTDAx76QwEj/rp D290ptsBkLCxyHYLr+hB1CR5X4mDjWsh1xhPaoMkP8lAdInBB6KvteKQbCkWMX07++bhjaVbAF8fT wwCMBjSDWjWvQi/rk836TuEAOGWuuN1sSPMhqdhxH1ix4/o4kC53JTDTxBpeVPlYidCiLUvSiK1B4 41Jo8JI8NyuTSUmXgGoOVLCfe/88eC0blHD5DwcdyjIUpxPTYAgo2XJrFywt3v7FpMJxpRywln131 VuUELUDwkwXD/Y82jpyRYxLXZxAEA9f1bIMg81V/PsaLAdwnynnBtabrvU9ARZoiIPV8c0wQxxZO2 J6iGP/tw==; Received: from 77-249-17-252.cable.dynamic.v4.ziggo.nl ([77.249.17.252] helo=noisy.programming.kicks-ass.net) by desiato.infradead.org with esmtpsa (Exim 4.99.2 #2 (Red Hat Linux)) id 1wd1bx-00000004aRi-2Rag; Fri, 26 Jun 2026 08:08:29 +0000 Received: by noisy.programming.kicks-ass.net (Postfix, from userid 1000) id 6C8F4300BDE; Fri, 26 Jun 2026 10:08:28 +0200 (CEST) Date: Fri, 26 Jun 2026 10:08:28 +0200 From: Peter Zijlstra To: Vincent Guittot Cc: K Prateek Nayak , mingo@redhat.com, juri.lelli@redhat.com, dietmar.eggemann@arm.com, rostedt@goodmis.org, bsegall@google.com, mgorman@suse.de, vschneid@redhat.com, linux-kernel@vger.kernel.org, qyousef@layalina.io Subject: Re: [PATCH 1/6 v3] sched/fair: Set next buddy for preempt short Message-ID: <20260626080828.GJ1181229@noisy.programming.kicks-ass.net> References: <20260624151229.1710703-1-vincent.guittot@linaro.org> <20260624151229.1710703-2-vincent.guittot@linaro.org> <07c84814-bbca-4c94-aebb-5ac0858efcfc@amd.com> <20260626065438.GG1181229@noisy.programming.kicks-ass.net> 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 Fri, Jun 26, 2026 at 09:02:09AM +0200, Vincent Guittot wrote: > > But I suppose you want to violate the strict deadline order, but in that > > yeah, and make sure that next is eligible > > > case we should still order on slice length. We should not set next when > > we already have one that is a shorter slice, no? > > set_next_buddy() is only called for PREEMPT_WAKEUP_SHORT which is only > used when (pse->slice < se->slice) with this patchset Right, but you can get multiple wakeups, and in that case you want to preserve the shortest slice, right?