From mboxrd@z Thu Jan 1 00:00:00 1970 From: Stephen Hemminger Subject: Re: [ofa-general] Re: [PATCH 2/3][NET_BATCH] net core use batching Date: Fri, 12 Oct 2007 10:05:00 -0700 Message-ID: <20071012100500.02255243@freepuppy.rosehill> References: <20071010003716.GB552@one.firstfloor.org> <36D9DB17C6DE9E40B059440DB8D95F5203887DD1@orsmsx418.amr.corp.intel.com> Mime-Version: 1.0 Content-Type: text/plain; charset=US-ASCII Content-Transfer-Encoding: 7bit Cc: "Andi Kleen" , "David Miller" , , , , , , , , , "Waskiewicz Jr, Peter P" , , , , , , , , To: "Brandeburg, Jesse" Return-path: Received: from smtp2.linux-foundation.org ([207.189.120.14]:54119 "EHLO smtp2.linux-foundation.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1758656AbXJLRKV (ORCPT ); Fri, 12 Oct 2007 13:10:21 -0400 In-Reply-To: <36D9DB17C6DE9E40B059440DB8D95F5203887DD1@orsmsx418.amr.corp.intel.com> Sender: netdev-owner@vger.kernel.org List-Id: netdev.vger.kernel.org On Fri, 12 Oct 2007 09:08:58 -0700 "Brandeburg, Jesse" wrote: > Andi Kleen wrote: > >> When the hw TX queue gains space, the driver self-batches packets > >> from the sw queue to the hw queue. > > > > I don't really see the advantage over the qdisc in that scheme. > > It's certainly not simpler and probably more code and would likely > > also not require less locks (e.g. a currently lockless driver > > would need a new lock for its sw queue). Also it is unclear to me > > it would be really any faster. > > related to this comment, does Linux have a lockless (using atomics) > singly linked list element? That would be very useful in a driver hot > path. Use RCU? or write a generic version and get it reviewed. You really want someone with knowledge of all the possible barrier impacts to review it. -- Stephen Hemminger