From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by smtp.lore.kernel.org (Postfix) with ESMTP id 9A712C43334 for ; Fri, 15 Jul 2022 14:14:22 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S235352AbiGOOOV (ORCPT ); Fri, 15 Jul 2022 10:14:21 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:42300 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S235359AbiGOOOM (ORCPT ); Fri, 15 Jul 2022 10:14:12 -0400 Received: from out5-smtp.messagingengine.com (out5-smtp.messagingengine.com [66.111.4.29]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 62E3714091; Fri, 15 Jul 2022 07:14:10 -0700 (PDT) Received: from compute4.internal (compute4.nyi.internal [10.202.2.44]) by mailout.nyi.internal (Postfix) with ESMTP id EA2735C00ED; Fri, 15 Jul 2022 10:14:07 -0400 (EDT) Received: from mailfrontend2 ([10.202.2.163]) by compute4.internal (MEProxy); Fri, 15 Jul 2022 10:14:07 -0400 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=kroah.com; h=cc :cc:content-type:date:date:from:from:in-reply-to:in-reply-to :message-id:mime-version:references:reply-to:sender:subject :subject:to:to; s=fm3; t=1657894447; x=1657980847; bh=xUs+Fa77kr OyO5S4vACFreFi4W0sYUD0E2jG/FaLPJ0=; b=uaewZsONjI/FGiYO1CmrPp94pQ +EbTpYs0zltsiN2zMcbuHKqz+tMuJBG+Sfyoi+Aqaea1aUVFy353BG9zI0sp+lPQ d4ikMUtESrDAACgDP8/Mwa0TB18rkhZyhHvR8tHBlnCeadx80VWnpbJ9ChQY4oZx 5IDXfBc9IufgaZsEr80vvyqBgtHfEuRuL87trpnzs/jzyZRdD0gpNll6V2t7XNac 0+ybP8HVbyc9Q/xc/9+WymO1XojBSD+/gziOUM/S1Vo3J7bLVaJRD8il3c3BLYPr ui9ozAf8Bg8fSr/ZmSCltcx2Fy5vTF50KUYT/+Np7PzNSO1yxuJlBXKIZQXA== DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d= messagingengine.com; h=cc:cc:content-type:date:date:feedback-id :feedback-id:from:from:in-reply-to:in-reply-to:message-id :mime-version:references:reply-to:sender:subject:subject:to:to :x-me-proxy:x-me-proxy:x-me-sender:x-me-sender:x-sasl-enc; s= fm3; t=1657894447; x=1657980847; bh=xUs+Fa77krOyO5S4vACFreFi4W0s YUD0E2jG/FaLPJ0=; b=SNTD2mKFMG7hVD/tArK44XjJLKLmu4pB0SPLWpq46sWe xuTJBQp/aMsPpt/b+0ZAQEGh+1j/d+mGrvkNWDtJYlHim4UJSXAHP/wAhtFIfmiX Fu8NoCYXo3mq/eywmwzNuNn44Q8c37zpLSxI7ktB2V0gz4819KN69EwQFuUNNNi+ 3JDTxUeruv+F9+yU892LZslG2HkThCroJktB5kAmjKGtwq1NJYE9rAG1R9mXucU2 DMj/r+Q8p08ZWN/STNeSgyogRekKO1/LKNZQ5A4TbTLzU7arSL7HqXr+L3IMnw10 KpEjSsePRapzvA4eHB0QuiyG3tgGCzAsKvN21FH3qg== X-ME-Sender: X-ME-Received: X-ME-Proxy-Cause: gggruggvucftvghtrhhoucdtuddrgedvfedrudekuddgjeeiucetufdoteggodetrfdotf fvucfrrhhofhhilhgvmecuhfgrshhtofgrihhlpdfqfgfvpdfurfetoffkrfgpnffqhgen uceurghilhhouhhtmecufedttdenucesvcftvggtihhpihgvnhhtshculddquddttddmne cujfgurhepfffhvfevuffkfhggtggujgesthdtredttddtvdenucfhrhhomhepifhrvghg ucfmjfcuoehgrhgvgheskhhrohgrhhdrtghomheqnecuggftrfgrthhtvghrnhepgeehue ehgfdtledutdelkeefgeejteegieekheefudeiffdvudeffeelvedttddvnecuffhomhgr ihhnpehkvghrnhgvlhdrohhrghenucevlhhushhtvghrufhiiigvpedtnecurfgrrhgrmh epmhgrihhlfhhrohhmpehgrhgvgheskhhrohgrhhdrtghomh X-ME-Proxy: Feedback-ID: i787e41f1:Fastmail Received: by mail.messagingengine.com (Postfix) with ESMTPA; Fri, 15 Jul 2022 10:14:05 -0400 (EDT) Date: Fri, 15 Jul 2022 16:14:01 +0200 From: Greg KH To: Mark-PK Tsai Cc: Ingo Molnar , Peter Zijlstra , Juri Lelli , Vincent Guittot , Dietmar Eggemann , Steven Rostedt , Ben Segall , Mel Gorman , Matthias Brugger , yj.chiang@mediatek.com, Daniel Bristot de Oliveira , stable@vger.kernel.org, linux-kernel@vger.kernel.org, linux-arm-kernel@lists.infradead.org, linux-mediatek@lists.infradead.org Subject: Re: [PATCH 5.4] sched/rt: Disable RT_RUNTIME_SHARE by default Message-ID: References: <20220714073055.15049-1-mark-pk.tsai@mediatek.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20220714073055.15049-1-mark-pk.tsai@mediatek.com> Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Thu, Jul 14, 2022 at 03:30:52PM +0800, Mark-PK Tsai wrote: > From: Daniel Bristot de Oliveira > > commit 2586af1ac187f6b3a50930a4e33497074e81762d upstream. > > The RT_RUNTIME_SHARE sched feature enables the sharing of rt_runtime > between CPUs, allowing a CPU to run a real-time task up to 100% of the > time while leaving more space for non-real-time tasks to run on the CPU > that lend rt_runtime. > > The problem is that a CPU can easily borrow enough rt_runtime to allow > a spinning rt-task to run forever, starving per-cpu tasks like kworkers, > which are non-real-time by design. > > This patch disables RT_RUNTIME_SHARE by default, avoiding this problem. > The feature will still be present for users that want to enable it, > though. > > Signed-off-by: Daniel Bristot de Oliveira > Signed-off-by: Peter Zijlstra (Intel) > Tested-by: Wei Wang > Link: https://lkml.kernel.org/r/b776ab46817e3db5d8ef79175fa0d71073c051c7.1600697903.git.bristot@redhat.com > Signed-off-by: Mark-PK Tsai > Cc: stable@vger.kernel.org > --- > kernel/sched/features.h | 2 +- > 1 file changed, 1 insertion(+), 1 deletion(-) Now queued up, thanks. greg k-h