Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1756388AbaDQAmx (ORCPT ); Wed, 16 Apr 2014 20:42:53 -0400 Received: from fgwmail5.fujitsu.co.jp ([192.51.44.35]:46218 "EHLO fgwmail5.fujitsu.co.jp" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1755083AbaDQAmu (ORCPT ); Wed, 16 Apr 2014 20:42:50 -0400 X-SecurityPolicyCheck: OK by SHieldMailChecker v1.7.4 Message-ID: <534F2374.8090304@jp.fujitsu.com> Date: Thu, 17 Apr 2014 09:42:28 +0900 From: Hidetoshi Seto User-Agent: Mozilla/5.0 (Windows NT 6.0; rv:24.0) Gecko/20100101 Thunderbird/24.0 MIME-Version: 1.0 To: Peter Zijlstra CC: linux-kernel@vger.kernel.org, Fernando Luis Vazquez Cao , Tetsuo Handa , Frederic Weisbecker , Thomas Gleixner , Ingo Molnar , Andrew Morton , Arjan van de Ven , Oleg Nesterov , Preeti U Murthy , Denys Vlasenko , stable@vger.kernel.org Subject: Re: [PATCH 2/2] nohz: use delayed iowait accounting to avoid race on idle time stats References: <53465F54.708@jp.fujitsu.com> <534660D2.1080505@jp.fujitsu.com> <20140415101910.GN11096@twins.programming.kicks-ass.net> <534E2422.1040706@jp.fujitsu.com> <20140416093637.GR11182@twins.programming.kicks-ass.net> In-Reply-To: <20140416093637.GR11182@twins.programming.kicks-ass.net> Content-Type: text/plain; charset=ISO-8859-1 Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org (2014/04/16 18:36), Peter Zijlstra wrote: > On Wed, Apr 16, 2014 at 03:33:06PM +0900, Hidetoshi Seto wrote: >> So we need 2 operations: >> a) remove regression > > What regression; there's never been talk about a regression, just a bug > found. AFAICT this 'regression' is ever since we introduced NOHZ or > somesuch, which is very long ago indeed. > > And since its basically been broken forever, there's no rush what so > ever. Well, from a customer's view, when he upgrade his foobar enterprise linux from version 5 to 6 (for example), he will say "it's a regression" if something worked well in previous version have broken in new version without any documents and/or technical notes etc. That's why I used the word "regression" for this bug. >> b) implement new iowait accounting mechanism >> >> What Frederic mentioned is that we don't need a) once if we invent >> the solution for b). But I doubt it because a) is still required >> for stable environment including some distributor's kernel. >> It is clear that patches for b) will not be backportable. >> >> Still the b) is disease that has no known cure. There is no reason >> to wait works on b) before starting works for a). > > As stated, there is no a). Its been forever broken. There is no urgency. I just wrote my patches for my customer like above and for my salary ;-) Thank you for your comments! I'll post my v4 patch set soon. Thanks, H.Seto -- 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/