From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from mta-65-227.siemens.flowmailer.net (mta-65-227.siemens.flowmailer.net [185.136.65.227]) (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 642D825D525 for ; Mon, 14 Apr 2025 08:54:56 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=185.136.65.227 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1744620903; cv=none; b=j4lehA36IyJIapRuz94VlmeWM9TzxO90gYZWsTRFbUIEMjFH4Bhezu0tDpfDHiPXqMUNhZzdZ0Q2m+bkx6Cbd0n77Hjbe8ce0pNtcO3KfDdmNBJYbmNWDn264s8RJKkHPqE9YPwbA3zeKEjaw3uXUQSFbjpeauenbW51uI4+OJw= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1744620903; c=relaxed/simple; bh=GICOfrRPaM3VxAz9clYPC3DMT67npjEodJIQmPxsfoI=; h=Message-ID:Subject:From:To:Cc:Date:In-Reply-To:References: Content-Type:MIME-Version; b=QMuK5zhDDq9vTwj7cOc+D3QxCVBAugiLe5NHblveJ2gcFyb/rf/TSdaGxTk+sY6GHIO2wc3/ZToylOXAz8Lc3LEmOxCYbRxYTh1MbqzSO+handlb4C5Oy4PxnqErmKOnbNcvNQfXZnS2TBLxcA9iJf1JMPPfpSykMUP95oUEurI= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dmarc=pass (p=reject dis=none) header.from=siemens.com; spf=pass smtp.mailfrom=rts-flowmailer.siemens.com; dkim=pass (2048-bit key) header.d=siemens.com header.i=florian.bezdeka@siemens.com header.b=YNo2GH5K; arc=none smtp.client-ip=185.136.65.227 Authentication-Results: smtp.subspace.kernel.org; dmarc=pass (p=reject dis=none) header.from=siemens.com Authentication-Results: smtp.subspace.kernel.org; spf=pass smtp.mailfrom=rts-flowmailer.siemens.com Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=siemens.com header.i=florian.bezdeka@siemens.com header.b="YNo2GH5K" Received: by mta-65-227.siemens.flowmailer.net with ESMTPSA id 20250414085449f2c4fe3c6abb47b6f7 for ; Mon, 14 Apr 2025 10:54:49 +0200 DKIM-Signature: v=1; a=rsa-sha256; q=dns/txt; c=relaxed/relaxed; s=fm2; d=siemens.com; i=florian.bezdeka@siemens.com; h=Date:From:Subject:To:Message-ID:MIME-Version:Content-Type:Content-Transfer-Encoding:Cc:References:In-Reply-To; bh=GICOfrRPaM3VxAz9clYPC3DMT67npjEodJIQmPxsfoI=; b=YNo2GH5Kh9fDsXfXE/Esxi2Qo+pNEy4aa/1ep+ivcddTzhHUbsCqQnoOLe0ZhHvcuwECPq UBg+uHLNjzpjJSIsAyx7Xh/r7JakZu8B/9THAf6eaEB5YX7yBUXMiHLGOwEYZ2nevtuB3HvN pDfxizKatApAoR3zwT8cd+K0fkOYAPBOGuDz6vCF8MUyb9YZ+xhEj83YpaaB0MzSL7EgL98l P2roX6TbWQiclrphKNKeQUwZVrBB6LilTvu7uZgXZFydvL9+I9GKKah9iUxaK6LzZStrv1NI me/sDHx2hrSvO8sDgVXX5O8WKKdKTksZWCHUu2Tmc5Gg3ybqGs1uTs5Q==; Message-ID: Subject: Re: [RFC PATCH v2 0/7] Defer throttle when task exits to user From: Florian Bezdeka To: Aaron Lu , Valentin Schneider , Ben Segall , K Prateek Nayak , Peter Zijlstra , Josh Don , Ingo Molnar , Vincent Guittot , Xi Wang Cc: linux-kernel@vger.kernel.org, Juri Lelli , Dietmar Eggemann , Steven Rostedt , Mel Gorman , Chengming Zhou , Chuyi Zhou , Jan Kiszka Date: Mon, 14 Apr 2025 10:54:48 +0200 In-Reply-To: <20250409120746.635476-1-ziqianlu@bytedance.com> References: <20250409120746.635476-1-ziqianlu@bytedance.com> Content-Type: text/plain; charset="UTF-8" Content-Transfer-Encoding: quoted-printable Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 X-Flowmailer-Platform: Siemens Feedback-ID: 519:519-68982:519-21489:flowmailer Hi Aaron, Hi Valentin, On Wed, 2025-04-09 at 20:07 +0800, Aaron Lu wrote: > This is a continuous work based on Valentin Schneider's posting here: > Subject: [RFC PATCH v3 00/10] sched/fair: Defer CFS throttle to user entr= y > https://lore.kernel.org/lkml/20240711130004.2157737-1-vschneid@redhat.com= / >=20 > Valentin has described the problem very well in the above link. We also > have task hung problem from time to time in our environment due to cfs qu= ota. > It is mostly visible with rwsem: when a reader is throttled, writer comes= in > and has to wait, the writer also makes all subsequent readers wait, > causing problems of priority inversion or even whole system hung. for testing purposes I backported this series to 6.14. We're currently hunting for a sporadic bug with PREEMPT_RT enabled. We see RCU stalls and complete system freezes after a couple of days with some container workload deployed. See [1].=C2=A0 It's too early to report "success", but this series seems to fix the circular dependency / system hang. Testing is still ongoing. While backporting I noticed some minor code style "issues". I will post them afterwards. Feel free to ignore... Best regards, Florian [1] https://lore.kernel.org/linux-rt-users/20250409135720.YuroItHp@linutron= ix.de/T/#t