From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1757603AbbCCXAx (ORCPT ); Tue, 3 Mar 2015 18:00:53 -0500 Received: from shelob.surriel.com ([74.92.59.67]:52030 "EHLO shelob.surriel.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1756417AbbCCXAZ (ORCPT ); Tue, 3 Mar 2015 18:00:25 -0500 From: riel@redhat.com To: tj@kernel.org Cc: linux-kernel@vger.kernel.org Subject: [PATCH v4 0/4] cpusets,isolcpus: exclude isolcpus from load balancing in cpusets Date: Tue, 3 Mar 2015 18:00:19 -0500 Message-Id: <1425423623-31316-1-git-send-email-riel@redhat.com> X-Mailer: git-send-email 2.1.0 Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Ensure that cpus specified with the isolcpus= boot commandline option stay outside of the load balancing in the kernel scheduler. Operations like load balancing can introduce unwanted latencies, which is exactly what the isolcpus= commandline is there to prevent. Previously, simply creating a new cpuset, without even touching the cpuset.cpus field inside the new cpuset, would undo the effects of isolcpus=, by creating a scheduler domain spanning the whole system, and setting up load balancing inside that domain. The cpuset root cpuset.cpus file is read-only, so there was not even a way to undo that effect. This does not impact the majority of cpusets users, since isolcpus= is a fairly specialized feature used for realtime purposes. This version fixes the UP compilation issue, in the same way done for the other cpumasks.