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 C2315C433EF for ; Tue, 19 Jul 2022 12:10:23 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S238429AbiGSMKT (ORCPT ); Tue, 19 Jul 2022 08:10:19 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:51634 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S238493AbiGSMIv (ORCPT ); Tue, 19 Jul 2022 08:08:51 -0400 Received: from dfw.source.kernel.org (dfw.source.kernel.org [IPv6:2604:1380:4641:c500::1]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id A263C50045; Tue, 19 Jul 2022 05:01:53 -0700 (PDT) Received: from smtp.kernel.org (relay.kernel.org [52.25.139.140]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by dfw.source.kernel.org (Postfix) with ESMTPS id 2200A616FB; Tue, 19 Jul 2022 12:01:53 +0000 (UTC) Received: by smtp.kernel.org (Postfix) with ESMTPSA id 05C2AC341CA; Tue, 19 Jul 2022 12:01:51 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=linuxfoundation.org; s=korg; t=1658232112; bh=ma7NhXFgC+7hwyuEmkcP1+W4Jkc830HpQ+gJrpBWGww=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=qDbFMGwbKqMmi+SVtySq6LrGW67wRT/k5qj/iumVfTkNV5tFRU+bIyXDKFgulOJqo Nlqpym5i3JRTFh4iH9qRY7VOcnDD4wTTFbqJTGzrW4FEwGpPE/TqeDvidaCTOFKLmt DnXJbN+KGx4zQaKMRulcyQi92rrb/UbsBhg8xYck= From: Greg Kroah-Hartman To: linux-kernel@vger.kernel.org Cc: Greg Kroah-Hartman , stable@vger.kernel.org, Daniel Bristot de Oliveira , "Peter Zijlstra (Intel)" , Wei Wang , Mark-PK Tsai Subject: [PATCH 5.4 17/71] sched/rt: Disable RT_RUNTIME_SHARE by default Date: Tue, 19 Jul 2022 13:53:40 +0200 Message-Id: <20220719114553.906618615@linuxfoundation.org> X-Mailer: git-send-email 2.37.1 In-Reply-To: <20220719114552.477018590@linuxfoundation.org> References: <20220719114552.477018590@linuxfoundation.org> User-Agent: quilt/0.66 MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.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 Signed-off-by: Greg Kroah-Hartman --- kernel/sched/features.h | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) --- 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)