From mboxrd@z Thu Jan 1 00:00:00 1970 From: lm@bitmover.com (Larry McVoy) Subject: Re: tcp bw in 2.6 Date: Tue, 2 Oct 2007 09:49:52 -0700 Message-ID: <20071002164952.GI17418@bitmover.com> References: <20071002005917.GB5480@bitmover.com> <20071002150935.GC17418@bitmover.com> <20071002154137.GD17418@bitmover.com> <20071002162534.GG17418@bitmover.com> <20071002094726.154fc619@freepuppy.rosehill> Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Cc: Larry McVoy , Herbert Xu , torvalds@linux-foundation.org, davem@davemloft.net, wscott@bitmover.com, netdev@vger.kernel.org To: Stephen Hemminger Return-path: Received: from ipcop.bitmover.com ([192.132.92.15]:43475 "EHLO mail.bitmover.com" rhost-flags-OK-OK-OK-FAIL) by vger.kernel.org with ESMTP id S1752775AbXJBQtx (ORCPT ); Tue, 2 Oct 2007 12:49:53 -0400 Content-Disposition: inline In-Reply-To: <20071002094726.154fc619@freepuppy.rosehill> Sender: netdev-owner@vger.kernel.org List-Id: netdev.vger.kernel.org On Tue, Oct 02, 2007 at 09:47:26AM -0700, Stephen Hemminger wrote: > On Tue, 2 Oct 2007 09:25:34 -0700 > lm@bitmover.com (Larry McVoy) wrote: > > > > If the server side is the source of the data, i.e, it's transfer is a > > > write loop, then I get the bad behaviour. > > > ... > > > So is this a bug or intentional? > > > > For whatever it is worth, I believed that we used to get better performance > > from the same hardware. My guess is that it changed somewhere between > > 2.6.15-1-k7 and 2.6.18-5-k7. > > For the period from 2.6.15 to 2.6.18, the kernel by default enabled TCP > Appropriate Byte Counting. This caused bad performance on applications that > did small writes. It's doing 1MB writes. Is there a sockopt to turn that off? Or /proc or something? -- --- Larry McVoy lm at bitmover.com http://www.bitkeeper.com