From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1752112AbYITQTa (ORCPT ); Sat, 20 Sep 2008 12:19:30 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1750786AbYITQTU (ORCPT ); Sat, 20 Sep 2008 12:19:20 -0400 Received: from casper.infradead.org ([85.118.1.10]:57054 "EHLO casper.infradead.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1750779AbYITQTT (ORCPT ); Sat, 20 Sep 2008 12:19:19 -0400 Date: Sat, 20 Sep 2008 09:19:18 -0700 From: Arjan van de Ven To: Daniel Walker Cc: David Miller , linux-kernel@vger.kernel.org, netdev@vger.kernel.org, jens.axboe@oracle.com, steffen.klassert@secunet.com Subject: Re: [PATCH 0/2]: Remote softirq invocation infrastructure. Message-ID: <20080920091918.0ffaef8c@infradead.org> In-Reply-To: <1221926529.1343.140.camel@localhost.localdomain> References: <20080919.234824.223177211.davem@davemloft.net> <1221924561.1343.121.camel@localhost.localdomain> <20080920084512.58f7fb08@infradead.org> <1221926529.1343.140.camel@localhost.localdomain> Organization: Intel X-Mailer: Claws Mail 3.5.0 (GTK+ 2.12.11; i386-redhat-linux-gnu) Mime-Version: 1.0 Content-Type: text/plain; charset=US-ASCII Content-Transfer-Encoding: 7bit X-SRS-Rewrite: SMTP reverse-path rewritten from by casper.infradead.org See http://www.infradead.org/rpr.html Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Sat, 20 Sep 2008 09:02:09 -0700 Daniel Walker wrote: > On Sat, 2008-09-20 at 08:45 -0700, Arjan van de Ven wrote: > > On Sat, 20 Sep 2008 08:29:21 -0700 > > > > > > > Jen's, as stated, has block layer uses for this. I intend to > > > > use this for receive side flow seperation on non-multiqueue > > > > network cards. And Steffen Klassert has a set of IPSEC > > > > parallelization changes that can very likely make use of this. > > > > > > What's the benefit that you (or Jens) sees from migrating softirqs > > > from specific cpu's to others? > > > > it means you do all the processing on the CPU that submitted the IO > > in the first place, and likely still has the various metadata > > pieces in its CPU cache (or at least you know you won't need to > > bounce them over) > > > In the case of networking and block I would think a lot of the softirq > activity is asserted from userspace.. Maybe the scheduler shouldn't be > migrating these tasks, or could take this softirq activity into > account .. well a lot of it comes from completion interrupts. and moving userspace isn't a good option; think of the case of 1 nic but 4 apache processes doing the work... -- Arjan van de Ven Intel Open Source Technology Centre For development, discussion and tips for power savings, visit http://www.lesswatts.org