Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1764859AbXF1R1O (ORCPT ); Thu, 28 Jun 2007 13:27:14 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1756936AbXF1R1A (ORCPT ); Thu, 28 Jun 2007 13:27:00 -0400 Received: from srv5.dvmed.net ([207.36.208.214]:50635 "EHLO mail.dvmed.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1758220AbXF1R07 (ORCPT ); Thu, 28 Jun 2007 13:26:59 -0400 Message-ID: <4683EF50.30108@garzik.org> Date: Thu, 28 Jun 2007 13:26:40 -0400 From: Jeff Garzik User-Agent: Thunderbird 1.5.0.12 (X11/20070530) MIME-Version: 1.0 To: Ingo Molnar , Steven Rostedt CC: Alexey Kuznetsov , Linus Torvalds , LKML , Andrew Morton , Thomas Gleixner , Christoph Hellwig , john stultz , Oleg Nesterov , "Paul E. McKenney" , Dipankar Sarma , "David S. Miller" , matthew.wilcox@hp.com Subject: Re: [RFC PATCH 0/6] Convert all tasklets to workqueues References: <20070622040014.234651401@goodmis.org> <20070622204058.GA11777@elte.hu> <20070622215953.GA22917@elte.hu> <46834BB8.1020007@garzik.org> <20070628092340.GB23566@elte.hu> <20070628143850.GA11780@ms2.inr.ac.ru> <20070628160001.GA15495@elte.hu> In-Reply-To: <20070628160001.GA15495@elte.hu> Content-Type: text/plain; charset=ISO-8859-1; format=flowed Content-Transfer-Encoding: 7bit X-Spam-Score: -4.3 (----) X-Spam-Report: SpamAssassin version 3.1.9 on srv5.dvmed.net summary: Content analysis details: (-4.3 points, 5.0 required) Sender: linux-kernel-owner@vger.kernel.org X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 1530 Lines: 36 Ingo Molnar wrote: > my argument was: workqueues are more scalable than tasklets in general. Here is my argument: that is totally irrelevant to $subject, when it comes to dealing with managing existing [network driver] behavior and performance. My overall objection is the attempt to replace apples with oranges. Network drivers use tasklets TODAY. Each driver -- in particular acenic, ns83820, and the 10Gbps drivers -- has been carefully tuned to use tasklets, hardirqs, and perhaps NAPI too. Changing to workqueue WILL affect network driver hot paths, yet I see no analysis or measurement at all of the behavior differences. If hackers are willing to revisit each network driver, rework the tasklet code to something more sane [in your opinion], and TEST it, I will review the patches and happily ACK away. Given that I feel that course of action is unlikely (the preferred alternative apparently being "I don't use these drivers, but surely my changes are OK anyway"), I do not see how this effort can proceed as is. Lots of time went into tuning these network drivers for the specific thread model they use. Maybe that thread model is no longer in style. Maybe modern machine behavior dictates a different approach. The point is... you don't know. Jeff - 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/