From mboxrd@z Thu Jan 1 00:00:00 1970 From: Hannes Frederic Sowa Subject: Re: [PATCH 0/2] Get rid of ndo_xmit_flush Date: Wed, 27 Aug 2014 14:31:12 +0200 Message-ID: <1409142672.26515.24.camel@localhost> References: <20140825.163458.1117073971092495452.davem@davemloft.net> Mime-Version: 1.0 Content-Type: text/plain; charset="UTF-8" Content-Transfer-Encoding: 7bit Cc: netdev@vger.kernel.org, therbert@google.com, jhs@mojatatu.com, edumazet@google.com, jeffrey.t.kirsher@intel.com, rusty@rustcorp.com.au, dborkman@redhat.com, brouer@redhat.com To: David Miller Return-path: Received: from out2-smtp.messagingengine.com ([66.111.4.26]:50835 "EHLO out2-smtp.messagingengine.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1756061AbaH0MbP (ORCPT ); Wed, 27 Aug 2014 08:31:15 -0400 Received: from compute3.internal (compute3.nyi.internal [10.202.2.43]) by gateway2.nyi.internal (Postfix) with ESMTP id 2253420A43 for ; Wed, 27 Aug 2014 08:31:15 -0400 (EDT) In-Reply-To: <20140825.163458.1117073971092495452.davem@davemloft.net> Sender: netdev-owner@vger.kernel.org List-ID: On Mo, 2014-08-25 at 16:34 -0700, David Miller wrote: > Given Jesper's performance numbers, it's not the way to go. > > Instead, go with a signalling scheme via new boolean skb->xmit_more. > > This has several advantages: > > 1) Nearly trivial driver support, just protect the tail pointer > update with the skb->xmit_more check. One thing one should keep in mind is, that there must be a skb available to trigger the flush, maybe this will hurt us one day. Thinking more about it should we go with a coccinelle script and replace/extend ndo_start_xmit with an additional argument? We can also add a new function pointer and call that instead of ndo_start_xmit. I think only the callq *%rax hurts performance. Bye, Hannes