From mboxrd@z Thu Jan 1 00:00:00 1970 From: David Miller Subject: Re: [PATCH 01/10] tcp: collapse more than two on retransmission Date: Mon, 24 Nov 2008 21:05:04 -0800 (PST) Message-ID: <20081124.210504.30738317.davem@davemloft.net> References: <1227536527-29713-1-git-send-email-ilpo.jarvinen@helsinki.fi> <1227536527-29713-2-git-send-email-ilpo.jarvinen@helsinki.fi> Mime-Version: 1.0 Content-Type: Text/Plain; charset=iso-8859-1 Content-Transfer-Encoding: QUOTED-PRINTABLE Cc: netdev@vger.kernel.org To: ilpo.jarvinen@helsinki.fi Return-path: Received: from 74-93-104-97-Washington.hfc.comcastbusiness.net ([74.93.104.97]:49384 "EHLO sunset.davemloft.net" rhost-flags-OK-FAIL-OK-OK) by vger.kernel.org with ESMTP id S1750793AbYKYFFF convert rfc822-to-8bit (ORCPT ); Tue, 25 Nov 2008 00:05:05 -0500 In-Reply-To: <1227536527-29713-2-git-send-email-ilpo.jarvinen@helsinki.fi> Sender: netdev-owner@vger.kernel.org List-ID: =46rom: "Ilpo J=E4rvinen" Date: Mon, 24 Nov 2008 16:21:58 +0200 > I always had thought that collapsing up to two at a time was > intentional decision to avoid excessive processing if 1 byte > sized skbs are to be combined for a full mtu, and consecutive > retransmissions would make the size of the retransmittee > double each round anyway, but some recent discussion made me > to understand that was not the case. Thus make collapse work > more and wait less. >=20 > It would be possible to take advantage of the shifting > machinery (added in the later patch) in the case of paged > data but that can be implemented on top of this change. Yes, the ->nr_frags test is a real limiter these days because on any modern device all TCP data is paged, whether sendmsg() or sendpage() generated. So you must have used a non-SG capable device for your tests or simply turned SG off using ethtool :) ... > Signed-off-by: Ilpo J=E4rvinen Applied, thanks!