From mboxrd@z Thu Jan 1 00:00:00 1970 From: Eric Dumazet Subject: Re: [PATCH v4 net-next] net: introduce dev_set_forwarding() Date: Thu, 07 Nov 2013 18:51:53 -0800 Message-ID: <1383879113.9412.155.camel@edumazet-glaptop2.roam.corp.google.com> References: <1383584130.1553.2.camel@bwh-desktop.uk.level5networks.com> <20131107.161755.355597965034457889.davem@davemloft.net> <20131107213111.GA6885@gondor.apana.org.au> <20131107.170651.1819930710384730745.davem@davemloft.net> <20131108021758.GA13467@gondor.apana.org.au> <1383878554.9412.153.camel@edumazet-glaptop2.roam.corp.google.com> Mime-Version: 1.0 Content-Type: text/plain; charset="UTF-8" Content-Transfer-Encoding: 7bit Cc: David Miller , bhutchings@solarflare.com, christoph.paasch@uclouvain.be, netdev@vger.kernel.org, hkchu@google.com, mwdalton@google.com To: Herbert Xu Return-path: Received: from mail-ie0-f180.google.com ([209.85.223.180]:51657 "EHLO mail-ie0-f180.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1754473Ab3KHCwe (ORCPT ); Thu, 7 Nov 2013 21:52:34 -0500 Received: by mail-ie0-f180.google.com with SMTP id e14so2286627iej.25 for ; Thu, 07 Nov 2013 18:52:33 -0800 (PST) In-Reply-To: <1383878554.9412.153.camel@edumazet-glaptop2.roam.corp.google.com> Sender: netdev-owner@vger.kernel.org List-ID: On Thu, 2013-11-07 at 18:42 -0800, Eric Dumazet wrote: > A normal TSO packets with 16 MSS setups a ~17 DMA descriptors, > while GSO requires 2 DMA descriptors per MSS, plus a lot of overhead > in sk_buff allocation/deallocation. Not mentioning fact that a 64KB packet is adding latencies, since high prio packets have to wait the whole preceding 64KB packet has left the host.