Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S934460AbaJ3PZI (ORCPT ); Thu, 30 Oct 2014 11:25:08 -0400 Received: from mail-qc0-f177.google.com ([209.85.216.177]:63315 "EHLO mail-qc0-f177.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751388AbaJ3PZG (ORCPT ); Thu, 30 Oct 2014 11:25:06 -0400 Date: Thu, 30 Oct 2014 11:25:02 -0400 From: Tejun Heo To: Peter Zijlstra Cc: Vikas Shivappa , "Auld, Will" , Matt Fleming , Vikas Shivappa , "linux-kernel@vger.kernel.org" , "Fleming, Matt" Subject: Re: Cache Allocation Technology Design Message-ID: <20141030152502.GA378@htj.dyndns.org> References: <20141029124834.GQ12020@console-pimps.org> <20141029134526.GC3337@twins.programming.kicks-ass.net> <96EC5A4F3149B74492D2D9B9B1602C27349EEB88@ORSMSX105.amr.corp.intel.com> <20141029172845.GP12706@worktop.programming.kicks-ass.net> <20141029182234.GA13393@mtj.dyndns.org> <20141030070725.GG3337@twins.programming.kicks-ass.net> <20141030071424.GE10476@twins.programming.kicks-ass.net> <20141030124440.GB29540@htj.dyndns.org> <20141030131904.GJ3337@twins.programming.kicks-ass.net> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20141030131904.GJ3337@twins.programming.kicks-ass.net> 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 Hello, Peter. On Thu, Oct 30, 2014 at 02:19:04PM +0100, Peter Zijlstra wrote: > On Thu, Oct 30, 2014 at 08:44:40AM -0400, Tejun Heo wrote: > > On Thu, Oct 30, 2014 at 08:14:24AM +0100, Peter Zijlstra wrote: > > > On Thu, Oct 30, 2014 at 08:07:25AM +0100, Peter Zijlstra wrote: > > > > > and always allow execution of member tasks. > > > > > > This too btw is not strictly speaking possible for all controllers. Most > > > all sched controllers live by the grace of forcing tasks not to run at > > > times (eg. the bandwidth controls), falsifying the 'always'. > > > > Oh sure, the a task just has to run in a foreseeable future, or > > rather, a task must not be blocked indefinitely requiring userland > > intervention to become executable again. > > Like the freezer cgroup you mean? ;-) Oh yeah, that's horribly broken. Merging it with jobctl stop is a todo item. This "stuck in a random place in kernel" thing made sense for suspend/hibernation only because the kernel wasn't gonna run anymore. The fact that this got exposed to userland on a running system just shows how little we were thinking while implementing all the controllers. It should be equivalent to layered job control stop so that what's prevented from running is the userland part, not kernel. Thanks. -- tejun -- 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/