From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1760257AbYDUDi1 (ORCPT ); Sun, 20 Apr 2008 23:38:27 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1760168AbYDUDiK (ORCPT ); Sun, 20 Apr 2008 23:38:10 -0400 Received: from 74-93-104-97-Washington.hfc.comcastbusiness.net ([74.93.104.97]:54967 "EHLO sunset.davemloft.net" rhost-flags-OK-FAIL-OK-OK) by vger.kernel.org with ESMTP id S1754694AbYDUDiJ (ORCPT ); Sun, 20 Apr 2008 23:38:09 -0400 Date: Sun, 20 Apr 2008 20:38:10 -0700 (PDT) Message-Id: <20080420.203810.183610437.davem@davemloft.net> To: herbert@gondor.apana.org.au Cc: mingo@elte.hu, dada1@cosmosbay.com, netdev@vger.kernel.org, linux-kernel@vger.kernel.org, a.p.zijlstra@chello.nl Subject: Re: poor network loopback performance and scalability From: David Miller In-Reply-To: References: <20080331113602.GA13526@elte.hu> X-Mailer: Mew version 5.2 on Emacs 22.1 / Mule 5.0 (SAKAKI) Mime-Version: 1.0 Content-Type: Text/Plain; charset=us-ascii Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org From: Herbert Xu Date: Mon, 21 Apr 2008 11:24:04 +0800 > Ingo Molnar wrote: > > > > # ifconfig lo mtu 1048576 > > Chiming in late here, but 1048576 can't possibly work with IP > which uses a 16-bit quantity as the length header. In fact a > quick test seems to indicate that an 1048576 mtu doesn't generate > anything bigger than the default 16K mtu. Right. To move things forward, we should look into doing something similar to what Al Viro suggested, which would be to return an SKB pointer from the transmit path and call back into netif_receive_skb() using that.