From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1754235AbZLWIdH (ORCPT ); Wed, 23 Dec 2009 03:33:07 -0500 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1753947AbZLWIdF (ORCPT ); Wed, 23 Dec 2009 03:33:05 -0500 Received: from hera.kernel.org ([140.211.167.34]:45562 "EHLO hera.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752788AbZLWIdB (ORCPT ); Wed, 23 Dec 2009 03:33:01 -0500 Message-ID: <4B31D5A7.2040608@kernel.org> Date: Wed, 23 Dec 2009 17:32:39 +0900 From: Tejun Heo User-Agent: Mozilla/5.0 (X11; U; Linux x86_64; en-US; rv:1.9.1.5) Gecko/20091130 SUSE/3.0.0-1.1.1 Thunderbird/3.0 MIME-Version: 1.0 To: Ingo Molnar CC: Linus Torvalds , Peter Zijlstra , awalls@radix.net, linux-kernel@vger.kernel.org, jeff@garzik.org, akpm@linux-foundation.org, jens.axboe@oracle.com, rusty@rustcorp.com.au, cl@linux-foundation.org, dhowells@redhat.com, arjan@linux.intel.com, avi@redhat.com, johannes@sipsolutions.net, andi@firstfloor.org Subject: Re: workqueue thing References: <1261387377.4314.37.camel@laptop> <4B2F7879.2080901@kernel.org> <1261405604.4314.154.camel@laptop> <4B3009DC.7020407@kernel.org> <1261480001.4937.21.camel@laptop> <4B319A20.9010305@kernel.org> <20091223060229.GA14805@elte.hu> <4B31C210.4010100@kernel.org> <20091223080144.GG23839@elte.hu> <20091223081238.GA29963@elte.hu> In-Reply-To: <20091223081238.GA29963@elte.hu> X-Enigmail-Version: 1.0 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 Hello, Ingo. On 12/23/2009 05:12 PM, Ingo Molnar wrote: > > * Ingo Molnar wrote: > >> At least as far as i'm concerned, i'd like to see actual uses. It's a big >> linecount increase all things considered: >> >> 20 files changed, 2783 insertions(+), 660 deletions(-) BTW, the code contains way more comment afterwards and has other benefits like not having crazy number of workers around on many core machines. >> and you say it _wont_ help performance/scalability (this aspect wasnt clear And I think it will help scalability for sure although it depends on what type of scalability you're talking about. >> to me from previous discussions), so the (yet to be seen) complexity >> reduction in other code ought to be worth it. > > To further stress this point, i'd like to point to the very first commit that > introduced kernel/workqueue.c into Linux 7 years ago: > > | From 6ed12ff83c765aeda7d38d3bf9df7d46d24bfb11 Mon Sep 17 00:00:00 2001 > | From: Ingo Molnar > | Date: Mon, 30 Sep 2002 22:17:42 -0700 > | Subject: [PATCH] [PATCH] Workqueue Abstraction > > look at the diffstat of that commit: > > 201 files changed, 1102 insertions(+), 1194 deletions(-) > > despite adding a new abstraction and kernel subsystem (workqueues), that > commit modified more than a hundred drivers to make use of it, and managed to > achieve a net linecount decrease of 92 lines - despite adding hundreds of > lines of a new core facility. > > Likewise, for this particular patchset it should be possible to identify > existing patterns of code in the existing code base of 6+ millions lines of > Linux driver code that would make the advantages of this +2000 lines of core > kernel code plain obvious. There were multipe claims of problems with the > current abstractions - so there sure must be a way to show off the new code in I'm not sure I'm gonna update that many places in a single sweep but yeah let's give it a shot. Thanks. -- tejun