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Mediocre TCP Performance 2.4.0 <-> Win98SE PPP

To: netdev@xxxxxxxxxxx
Subject: Mediocre TCP Performance 2.4.0 <-> Win98SE PPP
From: Jordan Mendelson <jordy@xxxxxxxxxxx>
Date: Fri, 05 Jan 2001 16:24:43 -0800
Organization: Napster, Inc.
Sender: owner-netdev@xxxxxxxxxxx
I reported this a couple of months back with 2.4.0-test10 and hoping
that it might have been fixed I tested 2.4.0 proper with no luck.

We are seeing a huge performance problem between 2.4.0 SMP and Windows
users dialed up using compressed PPP. The Linux box is a standard
valinux dual p3 running 2.4.0 without TCP ECN and without mmapped
network IO connected to a Cisco 6509 which is then connected to the
Internet. The Windows machine is a running 98SE 4.10.2222 dialed up to
an ISP over it's built in modem.

Basically, the Windows machine attempts to connect to the Linux box and
exchanges a few packets for login. The Linux box then dumps a roughly
~2.5K of data to the Windows machines via ~30 individual send() calls.
The Windows machine however fails to get the data or it ends up being
corrupted and retransmits are triggered.

With the exact same hardware and software running, but using 2.2.16
instead of 2.4.0 on the Linux box, everything appears to be ok.

I've attached two tcpdumps... one from a connection to 2.4.0 and one to
2.2.16. These are actually from the original mail I posted with
2.4.0-test10.

Unfortunatly, until this gets fixed we can't roll out 2.4.0 on our
production servers as a good number of users complain their connections
to the Napster service are extremely slow while it's running even though
the performance appeared to be significantly better the last time we
tested it.


Jordan
22:00:39.625351 209.179.245.186.1092 > 64.124.41.179.8888: S 4155530:4155530(0) 
win 8192 <mss 536,nop,nop,sackOK> (DF)
22:00:39.625437 64.124.41.179.8888 > 209.179.245.186.1092: S 
1301092473:1301092473(0) ack 4155531 win 5840 <mss 1460,nop,nop,sackOK> (DF)
22:00:39.887133 209.179.245.186.1092 > 64.124.41.179.8888: . ack 1 win 8576 (DF)
22:00:39.887969 209.179.245.186.1092 > 64.124.41.179.8888: . ack 1 win 65280 
(DF)
22:00:39.888951 209.179.245.186.1092 > 64.124.41.179.8888: P 1:44(43) ack 1 win 
65280 (DF)
22:00:39.888964 64.124.41.179.8888 > 209.179.245.186.1092: . ack 44 win 5840 
(DF)
22:00:39.991515 64.124.41.179.8888 > 209.179.245.186.1092: P 1:21(20) ack 44 
win 5840 (DF)
22:00:39.991660 64.124.41.179.8888 > 209.179.245.186.1092: P 21:557(536) ack 44 
win 5840 (DF)
22:00:42.991490 64.124.41.179.8888 > 209.179.245.186.1092: P 1:21(20) ack 44 
win 5840 (DF)
22:00:43.180946 209.179.245.186.1092 > 64.124.41.179.8888: P 44:56(12) ack 21 
win 65260 (DF)
22:00:43.180997 64.124.41.179.8888 > 209.179.245.186.1092: P 21:557(536) ack 44 
win 5840 (DF)
22:00:43.181025 64.124.41.179.8888 > 209.179.245.186.1092: P 557:1093(536) ack 
56 win 5840 (DF)
22:00:45.685143 209.179.245.186.1092 > 64.124.41.179.8888: P 44:456(412) ack 21 
win 65260 (DF)
22:00:45.685204 64.124.41.179.8888 > 209.179.245.186.1092: . ack 456 win 6432 
<nop,nop, sack 1 {44:56} > (DF)
22:00:49.171046 64.124.41.179.8888 > 209.179.245.186.1092: P 21:557(536) ack 
456 win 6432 (DF)
22:00:49.470193 209.179.245.186.1092 > 64.124.41.179.8888: . ack 557 win 65280 
(DF)
22:00:49.470233 64.124.41.179.8888 > 209.179.245.186.1092: P 557:1093(536) ack 
456 win 6432 (DF)
22:00:49.470248 64.124.41.179.8888 > 209.179.245.186.1092: P 1093:1629(536) ack 
456 win 6432 (DF)
22:01:01.461056 64.124.41.179.8888 > 209.179.245.186.1092: P 557:1093(536) ack 
456 win 6432 (DF)
22:01:01.755362 209.179.245.186.1092 > 64.124.41.179.8888: . ack 1093 win 65280 
(DF)
22:01:01.755428 64.124.41.179.8888 > 209.179.245.186.1092: P 1093:1629(536) ack 
456 win 6432 (DF)
22:01:01.755451 64.124.41.179.8888 > 209.179.245.186.1092: P 1629:1825(196) ack 
456 win 6432 (DF)
22:01:25.751048 64.124.41.179.8888 > 209.179.245.186.1092: P 1093:1629(536) ack 
456 win 6432 (DF)
22:01:26.171932 209.179.245.186.1092 > 64.124.41.179.8888: . ack 1629 win 65280 
(DF)
22:01:26.171979 64.124.41.179.8888 > 209.179.245.186.1092: P 1629:1825(196) ack 
456 win 6432 (DF)
22:02:14.171052 64.124.41.179.8888 > 209.179.245.186.1092: P 1629:1825(196) ack 
456 win 6432 (DF)
22:02:14.499920 209.179.245.186.1092 > 64.124.41.179.8888: . ack 1825 win 65084 
(DF)
22:02:14.499944 64.124.41.179.8888 > 209.179.245.186.1092: P 1825:1847(22) ack 
456 win 6432 (DF)
22:02:16.168708 209.179.245.186.1092 > 64.124.41.179.8888: F 456:456(0) ack 
1825 win 65084 (DF)
22:02:16.181061 64.124.41.179.8888 > 209.179.245.186.1092: . ack 457 win 6432 
(DF)
22:02:16.281724 64.124.41.179.8888 > 209.179.245.186.1092: F 1847:1847(0) ack 
457 win 6432 (DF)
22:02:16.477943 209.179.245.186.1092 > 64.124.41.179.8888: . ack 1825 win 65084 
<nop,nop, sack 1 {1847:1848} > (DF)
22:03:50.491063 64.124.41.179.8888 > 209.179.245.186.1092: P 1825:1847(22) ack 
457 win 6432 (DF)
22:03:50.680141 209.179.245.186.1092 > 64.124.41.179.8888: R 4155987:4155987(0) 
win 0 (DF)
22:00:01.684927 209.179.245.186.1091 > 64.124.41.136.8888: S 4033171:4033171(0) 
win 8192 <mss 536,nop,nop,sackOK> (DF)
22:00:01.685021 64.124.41.136.8888 > 209.179.245.186.1091: S 
1261602556:1261602556(0) ack 4033172 win 32696 <mss 536,nop,nop,sackOK> (DF)
22:00:01.916120 209.179.245.186.1091 > 64.124.41.136.8888: . ack 1 win 8576 (DF)
22:00:01.916191 209.179.245.186.1091 > 64.124.41.136.8888: . ack 1 win 65280 
(DF)
22:00:01.916981 209.179.245.186.1091 > 64.124.41.136.8888: P 1:44(43) ack 1 win 
65280 (DF)
22:00:01.917032 64.124.41.136.8888 > 209.179.245.186.1091: . ack 44 win 32696 
(DF)
22:00:02.121143 64.124.41.136.8888 > 209.179.245.186.1091: P 1:21(20) ack 44 
win 32696 (DF)
22:00:02.121279 64.124.41.136.8888 > 209.179.245.186.1091: P 21:349(328) ack 44 
win 32696 (DF)
22:00:02.327779 209.179.245.186.1091 > 64.124.41.136.8888: . ack 349 win 64932 
(DF)
22:00:02.327813 64.124.41.136.8888 > 209.179.245.186.1091: P 349:885(536) ack 
44 win 32696 (DF)
22:00:02.327825 64.124.41.136.8888 > 209.179.245.186.1091: P 885:1408(523) ack 
44 win 32696 (DF)
22:00:02.328909 209.179.245.186.1091 > 64.124.41.136.8888: P 44:56(12) ack 349 
win 64932 (DF)
22:00:02.340110 64.124.41.136.8888 > 209.179.245.186.1091: . ack 56 win 32696 
(DF)
22:00:02.605282 209.179.245.186.1091 > 64.124.41.136.8888: P 56:456(400) ack 
885 win 65280 (DF)
22:00:02.608462 209.179.245.186.1091 > 64.124.41.136.8888: . ack 1408 win 64757 
(DF)
22:00:02.608533 64.124.41.136.8888 > 209.179.245.186.1091: P 1408:1420(12) ack 
456 win 32296 (DF)
22:00:02.766833 64.124.41.136.8888 > 209.179.245.186.1091: P 1420:1689(269) ack 
456 win 32696 (DF)
22:00:02.889731 209.179.245.186.1091 > 64.124.41.136.8888: . ack 1420 win 64745 
(DF)
22:00:03.091796 209.179.245.186.1091 > 64.124.41.136.8888: . ack 1689 win 65280 
(DF)
22:00:03.091829 64.124.41.136.8888 > 209.179.245.186.1091: P 1689:1822(133) ack 
456 win 32696 (DF)
22:00:03.388700 209.179.245.186.1091 > 64.124.41.136.8888: . ack 1822 win 65147 
(DF)
22:00:04.442114 209.179.245.186.1091 > 64.124.41.136.8888: F 456:456(0) ack 
1822 win 65147 (DF)
22:00:04.442178 64.124.41.136.8888 > 209.179.245.186.1091: . ack 457 win 32696 
(DF)
22:00:04.502433 64.124.41.136.8888 > 209.179.245.186.1091: F 1822:1822(0) ack 
457 win 32696 (DF)
22:00:04.689026 209.179.245.186.1091 > 64.124.41.136.8888: . ack 1823 win 65147 
(DF)
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