Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1760566AbXFVWTm (ORCPT ); Fri, 22 Jun 2007 18:19:42 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1754054AbXFVWTe (ORCPT ); Fri, 22 Jun 2007 18:19:34 -0400 Received: from homer.mvista.com ([63.81.120.158]:30901 "EHLO gateway-1237.mvista.com" rhost-flags-OK-FAIL-OK-OK) by vger.kernel.org with ESMTP id S1752442AbXFVWTd (ORCPT ); Fri, 22 Jun 2007 18:19:33 -0400 Subject: Re: [RFC PATCH 0/6] Convert all tasklets to workqueues From: Daniel Walker To: david@lang.hm Cc: Ingo Molnar , Linus Torvalds , Steven Rostedt , LKML , Andrew Morton , Thomas Gleixner , Christoph Hellwig , john stultz , Oleg Nesterov , "Paul E. McKenney" , Dipankar Sarma , "David S. Miller" , matthew.wilcox@hp.com, kuznet@ms2.inr.ac.ru In-Reply-To: References: <20070622040014.234651401@goodmis.org> <20070622204058.GA11777@elte.hu> <1182549202.3228.78.camel@dhcp193.mvista.com> Content-Type: text/plain Date: Fri, 22 Jun 2007 15:15:32 -0700 Message-Id: <1182550533.3228.87.camel@dhcp193.mvista.com> Mime-Version: 1.0 X-Mailer: Evolution 2.10.2 (2.10.2-2.fc7) Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 1944 Lines: 48 On Fri, 2007-06-22 at 15:09 -0700, david@lang.hm wrote: > On Fri, 22 Jun 2007, Daniel Walker wrote: > > > > > On Fri, 2007-06-22 at 22:40 +0200, Ingo Molnar wrote: > > > >> > >> - tasklets have certain fairness limitations. (they are executed in > >> softirq context and thus preempt everything, even if there is some > >> potentially more important, high-priority task waiting to be > >> executed.) > > > > Since -rt has been executing tasklets in process context for a long > > time, I'm not sure this change would cause to many regressions. However, > > it seems like implicit dependencies on "tasklets preempt everything" > > might crop up. The other issue is if they don't "preempt > > everything" (most of the time), what default priority do we give them > > (all of the time)? It seems like Christoph's suggestion of converting > > all the tasklets individually might be a better option, to deal with > > specific pitfalls. > > that would be the safe way to do it, but it will take a lot of time and a > lot of testing. > > it's probably better to try the big-bang change and only if you see > problames go back and break things down. For testing I'd agree, but not for a kernel that is suppose to be stable. > remember, these changes have been in use in -rt for a while. there's > reason to believe that they aren't going to cause drastic problems. Since I've been working with -rt (~2 years now I think) it's clear that the number of testers of the patch isn't all that high compared to the stable kernel . There are tons of drivers which get no coverage by -rt patch users. So the fact that something similar is in -rt is good, but it's not a silver bullet .. Daniel - 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/