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 467891DDC26 for ; Fri, 8 Nov 2024 08:31:44 +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=1731054707; cv=none; b=Kvt4netJevJiziqbG9ceqxJ16kf00ql/sXwqBsR+fcgkhx7UvEMv/62UibVvVxt/XGe1FpB+/XowVftJO20cDyPg84VQKOoYRM1ZW+wQO7DaLEfKoCG4Zst5WQA4sYMcVoXyXfUH4UlS/Q+0p1DeADViKLuGOXgFRjLKbj3/ojI= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1731054707; c=relaxed/simple; bh=Af+ibQAcn9VYqAgUjp/SlyL+YVC9zLwX1LqXg3dG/+8=; h=Date:From:To:Cc:Subject:Message-ID:References:MIME-Version: Content-Type:Content-Disposition:In-Reply-To; b=I0ngOXBMN5VtwtugTKuvza73zYSVtPpYCbkau6PgMfXCkLTIRowcKFeuLvNx3xAD/9Dfe0/5NLU9Y7jOmEOa9dAeAKEkbJExUbBHfQsd1KQtpFOt9LPqjETi6Wf8xFsUXQjbZdJDTjUHyk8gMiq4eqpPGkyiyEMQBQKexRIGx1s= 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=eHsfqcZC; 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="eHsfqcZC" 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=U5iXxYbAfJjSDxBL5j4rJye+EBOI58DLKjlS8UohSOU=; b=eHsfqcZC9y9l0uyhJnHfEV+lg6 XhnQo0+5QPoEgvUehPXlppWxbOckzZTbUSDqJifW4fI2q9BO6Ov5hLp0X3T3g9UargZrsho5E4+U9 mQRJrYg4VlQD/7/K4LGiuoGhNDa0oZ99MUkr92pw4V7mLWxXPEzz3OWm2HXygHiYYH8Muh7VN4V96 H6qKuhoYk5o2j8CTyUNhTIpp/05vzcQKpWygt73YN76Hhjan+ZbMc1V2Jv0NVJ1Xu2G7X5NmrT1eD fugsEc/yB74Qsq6zmcd2JYfjjKXN26/IR/cLgWiEeUB8g7NfLPKBiaQAJSxyKRZMZ3QAjnyvgyUD0 Ve35pb0w==; Received: from j130084.upc-j.chello.nl ([24.132.130.84] helo=noisy.programming.kicks-ass.net) by casper.infradead.org with esmtpsa (Exim 4.98 #2 (Red Hat Linux)) id 1t9KOz-00000008Yx9-3PHV; Fri, 08 Nov 2024 08:31:34 +0000 Received: by noisy.programming.kicks-ass.net (Postfix, from userid 1000) id 7A3D830049D; Fri, 8 Nov 2024 09:31:33 +0100 (CET) Date: Fri, 8 Nov 2024 09:31:33 +0100 From: Peter Zijlstra To: Saravana Kannan Cc: Ingo Molnar , Juri Lelli , Vincent Guittot , Dietmar Eggemann , Steven Rostedt , Benjamin Segall , Mel Gorman , Valentin Schneider , LKML , wuyun.abel@bytedance.com, youssefesmat@chromium.org, Thomas Gleixner , efault@gmx.de, K Prateek Nayak , John Stultz , Vincent Palomares Subject: Re: Very high scheduling delay with plenty of idle CPUs Message-ID: <20241108083133.GD38786@noisy.programming.kicks-ass.net> References: 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 Thu, Nov 07, 2024 at 11:28:07PM -0800, Saravana Kannan wrote: > Hi scheduler folks, > > I'm running into some weird scheduling issues when testing non-sched > changes on a Pixel 6 that's running close to 6.12-rc5. I'm not sure if > this is an issue in earlier kernel versions or not. > It's a bit unfortunate you don't have a known good kernel there. Anyway, one thing that recently came up is that DELAY_DEQUEUE can cause some delays, specifically it can inhibit wakeup migration. You can either test with that feature turned off, or apply something like the following patch: https://lkml.kernel.org/r/20241106135346.GL24862@noisy.programming.kicks-ass.net