From mboxrd@z Thu Jan 1 00:00:00 1970 From: jamal Subject: Re: [PATCH] NET: Multiqueue network device support. Date: Wed, 06 Jun 2007 19:54:47 -0400 Message-ID: <1181174087.4064.100.camel@localhost> References: <1181082517.4062.31.camel@localhost> <4666CEB7.6030804@trash.net> <1181168020.4064.46.camel@localhost> <20070606.153530.48530367.davem@davemloft.net> <1181172766.4064.83.camel@localhost> <466747EB.5020101@hp.com> Reply-To: hadi@cyberus.ca Mime-Version: 1.0 Content-Type: text/plain Content-Transfer-Encoding: 7bit Cc: David Miller , kaber@trash.net, peter.p.waskiewicz.jr@intel.com, netdev@vger.kernel.org, jeff@garzik.org, auke-jan.h.kok@intel.com To: Rick Jones Return-path: Received: from py-out-1112.google.com ([64.233.166.183]:50860 "EHLO py-out-1112.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1755841AbXFFXyv (ORCPT ); Wed, 6 Jun 2007 19:54:51 -0400 Received: by py-out-1112.google.com with SMTP id a29so568230pyi for ; Wed, 06 Jun 2007 16:54:50 -0700 (PDT) In-Reply-To: <466747EB.5020101@hp.com> Sender: netdev-owner@vger.kernel.org List-Id: netdev.vger.kernel.org On Wed, 2007-06-06 at 16:48 -0700, Rick Jones wrote: > > RX queues - yes, I can see; TX queues, it doesnt make sense to put > > different rings on different CPUs. > > To what extent might that preclude some cachelines bouncing hither and > yon between the CPUs? I think the bouncing will exist a lot more with the multi CPUs. But one would assume if you go that path, you would also parallelize the stack on egress to reduce such an effect. I guess the point i am not seeing is the value. The tx, once hitting the NIC is an IO issue not a CPU issue. OTOH, the receive path once a packet is received, that is a CPU problem (and therefore multi CPUs help). To be fair to Peter, that is not what his patches are trying to address (and infact, they cant solve that problem). off for the night. cheers, jamal