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 X-Spam-Level: X-Spam-Status: No, score=-3.8 required=3.0 tests=HEADER_FROM_DIFFERENT_DOMAINS, MAILING_LIST_MULTI,SPF_HELO_NONE,SPF_PASS,USER_AGENT_GIT autolearn=no autolearn_force=no version=3.4.0 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id 97750C32751 for ; Wed, 7 Aug 2019 17:41:15 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 72D3021E6E for ; Wed, 7 Aug 2019 17:41:15 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S2389201AbfHGRlO (ORCPT ); Wed, 7 Aug 2019 13:41:14 -0400 Received: from foss.arm.com ([217.140.110.172]:52506 "EHLO foss.arm.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S2388371AbfHGRlN (ORCPT ); Wed, 7 Aug 2019 13:41:13 -0400 Received: from usa-sjc-imap-foss1.foss.arm.com (unknown [10.121.207.14]) by usa-sjc-mx-foss1.foss.arm.com (Postfix) with ESMTP id 2F50528; Wed, 7 Aug 2019 10:41:11 -0700 (PDT) Received: from e113632-lin.cambridge.arm.com (e113632-lin.cambridge.arm.com [10.1.194.37]) by usa-sjc-imap-foss1.foss.arm.com (Postfix) with ESMTPA id 583813F575; Wed, 7 Aug 2019 10:41:10 -0700 (PDT) From: Valentin Schneider To: linux-kernel@vger.kernel.org Cc: mingo@kernel.org, peterz@infradead.org, vincent.guittot@linaro.org Subject: [PATCH 0/3] sched/fair: Active balancer RT/DL preemption fix Date: Wed, 7 Aug 2019 18:40:23 +0100 Message-Id: <20190807174026.31242-1-valentin.schneider@arm.com> X-Mailer: git-send-email 2.22.0 MIME-Version: 1.0 Content-Transfer-Encoding: 8bit Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Vincent's load balance rework [1] got me thinking about how and where we use rq.nr_running vs rq.cfs.h_nr_running checks, and this lead me to stare intently at the active load balancer. I haven't seen it happen (yet), but from reading the code it really looks like we can have some scenarios where the cpu_stopper ends up preempting a > CFS class task. - Patch 1 is a preparatory code move - Patch 2 is the actual fix - Patch 3 is a related fix for the cpu_stopper function This is based on top of today's tip/sched/core: a1dc0446d649 ("sched/core: Silence a warning in sched_init()") @Vincent: I don't think this should conflict too badly with your rework, but if you have any issues I'll try to give you a version rebased on top of the rework. [1]: https://lore.kernel.org/lkml/1564670424-26023-1-git-send-email-vincent.guittot@linaro.org/ Valentin Schneider (3): sched/fair: Move active balance logic to its own function sched/fair: Prevent active LB from preempting higher sched classes sched/fair: Check for CFS tasks in active_load_balance_cpu_stop() kernel/sched/fair.c | 130 +++++++++++++++++++++++++++----------------- 1 file changed, 79 insertions(+), 51 deletions(-) -- 2.22.0