From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S934412AbcKOKjx (ORCPT ); Tue, 15 Nov 2016 05:39:53 -0500 Received: from mx1.redhat.com ([209.132.183.28]:60892 "EHLO mx1.redhat.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1754177AbcKOKj2 (ORCPT ); Tue, 15 Nov 2016 05:39:28 -0500 From: Daniel Bristot de Oliveira To: Ingo Molnar , Peter Zijlstra Cc: Steven Rostedt , Clark Williams , "Luis Claudio R . Goncalves" , linux-kernel@vger.kernel.org Subject: [PATCH 1/2] sched/rt: Disable RT_RUNTIME_SHARE by default Date: Tue, 15 Nov 2016 11:39:10 +0100 Message-Id: In-Reply-To: References: X-Greylist: Sender IP whitelisted, not delayed by milter-greylist-4.5.16 (mx1.redhat.com [10.5.110.31]); Tue, 15 Nov 2016 10:39:28 +0000 (UTC) Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org 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 Cc: Ingo Molnar Cc: Peter Zijlstra Cc: Steven Rostedt Cc: Clark Williams Cc: Luis Claudio R. Goncalves Cc: linux-kernel@vger.kernel.org diff --git a/kernel/sched/features.h b/kernel/sched/features.h index 69631fa..5fffebfe 100644 --- a/kernel/sched/features.h +++ b/kernel/sched/features.h @@ -65,7 +65,7 @@ SCHED_FEAT(RT_PUSH_IPI, true) #endif SCHED_FEAT(FORCE_SD_OVERLAP, false) -SCHED_FEAT(RT_RUNTIME_SHARE, true) +SCHED_FEAT(RT_RUNTIME_SHARE, false) SCHED_FEAT(LB_MIN, false) SCHED_FEAT(ATTACH_AGE_LOAD, true) -- 2.7.4