From mboxrd@z Thu Jan 1 00:00:00 1970 From: Nivedita Singhvi Subject: Re: 2.6.10 TCP troubles -- suggested patch Date: Fri, 11 Feb 2005 15:09:11 -0800 Message-ID: <420D3B17.3040506@us.ibm.com> References: <0525M9211@server5.heliogroup.fr> <420D37A3.6020209@hp.com> Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii; format=flowed Content-Transfer-Encoding: 7bit Cc: Hubert Tonneau , "David S. Miller" , shemminger@osdl.org, romieu@fr.zoreil.com, kuznet@ms2.inr.ac.ru, netdev@oss.sgi.com To: Rick Jones In-Reply-To: <420D37A3.6020209@hp.com> Sender: netdev-bounce@oss.sgi.com Errors-to: netdev-bounce@oss.sgi.com List-Id: netdev.vger.kernel.org Rick Jones wrote: > 000010 10.107.96.7.32801 > 10.107.96.230.139: . 11692:13140(1448) ack > 822 win 1460 NBT Packet (DF) > 000004 10.107.96.7.32801 > 10.107.96.230.139: . 13140:14588(1448) ack > 822 win 1460 NBT Packet (DF) > 000002 10.107.96.7.32801 > 10.107.96.230.139: P 14588:16036(1448) ack > 822 win 1460 NBT Packet (DF) > 000022 10.107.96.7.32801 > 10.107.96.230.139: . 16036:17484(1448) ack > 822 win 1460 NBT Packet (DF) > 000004 10.107.96.7.32801 > 10.107.96.230.139: P 17484:18192(708) ack 822 > win 1460 NBT Packet (DF) > 000994 10.107.96.230.139 > 10.107.96.7.32801: . ack 18192 win 65535 > (DF) > 0 > > And then other cases where the ACK seems to take a rather long time to > arrive, seems to correlate a bit with slowly increasing numbers of > segments before the ACK is sent, and something along the lines of a 200 > millisecond delayed ACK timer. > > In some cases at least if the sender does not completely fill cwnd the > ACKs will be delayed. And IIRC under 2.6.10 with TSO enabled, the > sender does not always fill cwnd. Er, how is this compliant with 2581 (yes, I know, it's only a SHOULD, not a MUST) - an ACK should be generated for at least every second full-sized segment received? Don't see that happening. In many cases it's receiving quite a few more packets. It should not be waiting for the delayed ack timer to go off, surely? thanks, Nivedita