From patchwork Thu Jul 14 07:30:52 2022 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: =?utf-8?b?TWFyay1QSyBUc2FpICjolKHmspvliZsp?= X-Patchwork-Id: 12917438 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 bombadil.infradead.org (bombadil.infradead.org [198.137.202.133]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.lore.kernel.org (Postfix) with ESMTPS id C96CCC43334 for ; Thu, 14 Jul 2022 08:12:02 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; q=dns/txt; c=relaxed/relaxed; d=lists.infradead.org; s=bombadil.20210309; h=Sender:List-Subscribe:List-Help :List-Post:List-Archive:List-Unsubscribe:List-Id:Content-Type:MIME-Version: Message-ID:Date:Subject:CC:To:From:Reply-To:Content-Transfer-Encoding: Content-ID:Content-Description:Resent-Date:Resent-From:Resent-Sender: Resent-To:Resent-Cc:Resent-Message-ID:In-Reply-To:References:List-Owner; bh=d2V5rB3R50IqeBfs7LX1P6FCozmqVAN64ExS2GEtUdk=; b=0LJ5kvgejHEDNfYaNHn3n0V6LS 2LsYF3UcC0KVPRPK6FpnAxiHerE9uaGNJe1KKVIbRy5NzAlr/k6+UXebTmfWzlC3tT1wt3kUSgIqa cnXjkrWhQsCW6Kfdc/YK9YsYc+vfNsbppG4bEvJkrR9HstMN1yWkXBINhvsdTlBrQBVO+35y2qsuT 3Eccfk6nVdM5J/c04ZJcs1DrxKhpsn2P093JVhBjaK/wZgwgLjBus6mpCFuzbtDDBqONCvB7KJM93 LUaqaLsQtCJjteAeC87uAw+XyV7w71NhYzBQo2ReuCq/q96FSxxc/3bzYidvm6/XoBCMN8G29JgH/ 8BxRgDuw==; Received: from localhost ([::1] helo=bombadil.infradead.org) by bombadil.infradead.org with esmtp (Exim 4.94.2 #2 (Red Hat Linux)) id 1oBtwu-00CDoa-Vz; Thu, 14 Jul 2022 08:11:53 +0000 Received: from mailgw02.mediatek.com ([216.200.240.185]) by bombadil.infradead.org with esmtps (Exim 4.94.2 #2 (Red Hat Linux)) id 1oBtwq-00CDim-VU; Thu, 14 Jul 2022 08:11:50 +0000 X-UUID: 97852d2c9375480ca1e1bb1c8c5d81be-20220714 X-CID-P-RULE: Release_Ham X-CID-O-INFO: VERSION:1.1.8,REQID:f30ea0e5-9098-490b-87a2-967933105e75,OB:0,LO B:0,IP:0,URL:0,TC:0,Content:-5,EDM:0,RT:0,SF:0,FILE:0,RULE:Release_Ham,ACT ION:release,TS:-5 X-CID-META: VersionHash:0f94e32,CLOUDID:6ecb4764-0b3f-4b2c-b3a6-ed5c044366a0,C OID:IGNORED,Recheck:0,SF:nil,TC:nil,Content:0,EDM:-3,IP:nil,URL:1,File:nil ,QS:nil,BEC:nil,COL:0 X-UUID: 97852d2c9375480ca1e1bb1c8c5d81be-20220714 Received: from mtkmbs11n1.mediatek.inc [(172.21.101.185)] by mailgw02.mediatek.com (envelope-from ) (musrelay.mediatek.com ESMTP with TLSv1.2 ECDHE-RSA-AES256-GCM-SHA384 256/256) with ESMTP id 863748906; Thu, 14 Jul 2022 01:11:41 -0700 Received: from mtkmbs11n1.mediatek.inc (172.21.101.185) by mtkmbs10n1.mediatek.inc (172.21.101.34) with Microsoft SMTP Server (version=TLS1_2, cipher=TLS_ECDHE_RSA_WITH_AES_256_GCM_SHA384) id 15.2.792.15; Thu, 14 Jul 2022 15:31:05 +0800 Received: from mtksdccf07.mediatek.inc (172.21.84.99) by mtkmbs11n1.mediatek.inc (172.21.101.73) with Microsoft SMTP Server id 15.2.792.3 via Frontend Transport; Thu, 14 Jul 2022 15:31:05 +0800 From: Mark-PK Tsai To: Ingo Molnar , Peter Zijlstra , Juri Lelli , Vincent Guittot , Dietmar Eggemann , Steven Rostedt , Ben Segall , "Mel Gorman" , Matthias Brugger CC: , Daniel Bristot de Oliveira , Mark-PK Tsai , , , , Subject: [PATCH 5.4] sched/rt: Disable RT_RUNTIME_SHARE by default Date: Thu, 14 Jul 2022 15:30:52 +0800 Message-ID: <20220714073055.15049-1-mark-pk.tsai@mediatek.com> X-Mailer: git-send-email 2.18.0 MIME-Version: 1.0 X-MTK: N X-CRM114-Version: 20100106-BlameMichelson ( TRE 0.8.0 (BSD) ) MR-646709E3 X-CRM114-CacheID: sfid-20220714_011149_086051_3E2C38B8 X-CRM114-Status: GOOD ( 12.42 ) X-BeenThere: linux-mediatek@lists.infradead.org X-Mailman-Version: 2.1.34 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Sender: "Linux-mediatek" Errors-To: linux-mediatek-bounces+linux-mediatek=archiver.kernel.org@lists.infradead.org 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(-) diff --git a/kernel/sched/features.h b/kernel/sched/features.h index 2410db5e9a35..66c74aa4753e 100644 --- a/kernel/sched/features.h +++ b/kernel/sched/features.h @@ -77,7 +77,7 @@ SCHED_FEAT(WARN_DOUBLE_CLOCK, false) SCHED_FEAT(RT_PUSH_IPI, true) #endif -SCHED_FEAT(RT_RUNTIME_SHARE, true) +SCHED_FEAT(RT_RUNTIME_SHARE, false) SCHED_FEAT(LB_MIN, false) SCHED_FEAT(ATTACH_AGE_LOAD, true)