Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S932256AbbELJK6 (ORCPT ); Tue, 12 May 2015 05:10:58 -0400 Received: from mail-wi0-f178.google.com ([209.85.212.178]:35030 "EHLO mail-wi0-f178.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751494AbbELJKh (ORCPT ); Tue, 12 May 2015 05:10:37 -0400 Date: Tue, 12 May 2015 11:10:32 +0200 From: Ingo Molnar To: Chris Metcalf Cc: Steven Rostedt , Frederic Weisbecker , Andrew Morton , paulmck@linux.vnet.ibm.com, Gilad Ben Yossef , Peter Zijlstra , Rik van Riel , Tejun Heo , Thomas Gleixner , Christoph Lameter , "Srivatsa S. Bhat" , linux-doc@vger.kernel.org, linux-api@vger.kernel.org, linux-kernel@vger.kernel.org Subject: CONFIG_ISOLATION=y (was: [PATCH 0/6] support "dataplane" mode for nohz_full) Message-ID: <20150512091032.GA10138@gmail.com> References: <20150508172210.559830a9@gandalf.local.home> <554D428E.6020702@ezchip.com> <20150508161909.308d60e21f6b83b897174276@linux-foundation.org> <20150509070538.GA9413@gmail.com> <20150511085759.71deeb64@gandalf.local.home> <20150511171916.GN6776@linux.vnet.ibm.com> <20150511102744.9ebb2d05a7e8b457d03430bf@linux-foundation.org> <20150511173305.GC32512@lerouge> <20150511140009.1f7bcf07@gandalf.local.home> <5550F077.6030906@ezchip.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <5550F077.6030906@ezchip.com> User-Agent: Mutt/1.5.23 (2014-03-12) Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 1711 Lines: 37 * Chris Metcalf wrote: > - ISOLATION (Frederic). I like this but it conflicts with other uses > of "isolation" in the kernel: cgroup isolation, lru page isolation, > iommu isolation, scheduler isolation (at least it's a superset of > that one), etc. Also, we're not exactly isolating a task - often > a "dataplane" app consists of a bunch of interacting threads in > userspace, so not exactly isolated. So perhaps it's too confusing. So I'd vote for Frederic's CONFIG_ISOLATION=y, mostly because this is a high level kernel feature, so it won't conflict with isolation concepts in lower level subsystems such as IOMMU isolation - and other higher level features like scheduler isolation are basically another partial implementation we want to merge with all this... nohz, RCU tricks, watchdog defaults, isolcpus and various other measures to keep these CPUs and workloads as isolated as possible are (or should become) components of this high level concept. Ideally CONFIG_ISOLATION=y would be a kernel feature that has almost zero overhead on normal workloads and on non-isolated CPUs, so that Linux distributions can enable it. Enabling CONFIG_ISOLATION=y should be the only 'kernel config' step needed: just like cpusets, the configuration of isolated CPUs should be a completely boot option free excercise that can be dynamically done and undone by the administrator via an intuitive interface. Thanks, Ingo -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/