From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1753982AbZLWIOg (ORCPT ); Wed, 23 Dec 2009 03:14:36 -0500 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1752860AbZLWIOf (ORCPT ); Wed, 23 Dec 2009 03:14:35 -0500 Received: from mx3.mail.elte.hu ([157.181.1.138]:48092 "EHLO mx3.mail.elte.hu" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752842AbZLWIOe (ORCPT ); Wed, 23 Dec 2009 03:14:34 -0500 Date: Wed, 23 Dec 2009 09:12:38 +0100 From: Ingo Molnar To: Tejun Heo 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 Message-ID: <20091223081238.GA29963@elte.hu> 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> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20091223080144.GG23839@elte.hu> User-Agent: Mutt/1.5.20 (2009-08-17) X-ELTE-SpamScore: -2.0 X-ELTE-SpamLevel: X-ELTE-SpamCheck: no X-ELTE-SpamVersion: ELTE 2.0 X-ELTE-SpamCheck-Details: score=-2.0 required=5.9 tests=BAYES_00 autolearn=no SpamAssassin version=3.2.5 -2.0 BAYES_00 BODY: Bayesian spam probability is 0 to 1% [score: 0.0000] Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org * 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(-) > > and you say it _wont_ help performance/scalability (this aspect wasnt clear > 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 a few places. Ingo