From mboxrd@z Thu Jan 1 00:00:00 1970 From: Rick Jones Subject: Re: tcp bw in 2.6 Date: Tue, 02 Oct 2007 12:47:41 -0700 Message-ID: <4702A05D.6020509@hp.com> References: <20070929142517.EC6AB5FB21@work.bitmover.com> <20070929172639.GB7037@bitmover.com> <20071002005917.GB5480@bitmover.com> <20071002022059.GE7037@bitmover.com> <47027C63.803@hp.com> <20071002172002.GO17418@bitmover.com> <4702878B.4040102@hp.com> <20071002184032.GB29944@bitmover.com> Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii; format=flowed Content-Transfer-Encoding: 7bit Cc: Linus Torvalds , davem@davemloft.net, wscott@bitmover.com, netdev@vger.kernel.org To: Larry McVoy Return-path: Received: from palrel13.hp.com ([156.153.255.238]:50288 "EHLO palrel13.hp.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752661AbXJBTrv (ORCPT ); Tue, 2 Oct 2007 15:47:51 -0400 In-Reply-To: <20071002184032.GB29944@bitmover.com> Sender: netdev-owner@vger.kernel.org List-Id: netdev.vger.kernel.org Larry McVoy wrote: > On Tue, Oct 02, 2007 at 11:01:47AM -0700, Rick Jones wrote: > >>has anyone already asked whether link-layer flow-control is enabled? > > > I doubt it, the same test works fine in one direction and poorly in the other. > Wouldn't the flow control squelch either way? While I am often guilty of it, a wise old engineer tried to teach me that the proper spelling is ass-u-me :) I wouldn't count on it hitting in both directions, depends on the specifics of the situation. WRT the HP-UX ACK avoidance heuristic, the default HP-UX socket buffer/window is 32768, and tcp_deferred_ack_max defaults to 22. That isn't really all that good a combination - with a window of 32768 11 for the deferred ack would be better. You could also go ahead and try it with a value of 2. Or, bump the window size defaults - tcp_recv_hiwater_def and tcp_xmit_hiwater_def - to say 65535 or 128K or something - or use the setsockopt() calls to effect that. rick jones