From: “Dave Ross” <davros@raf.com>
To: <cypherpunks@toad.com>
Message Hash: 62db12aed501170900779441fceab8d9d436704d87979f1145d065f32640ffd5
Message ID: <m0wy50o-000sS8C@fred.raf.com>
Reply To: N/A
UTC Datetime: 1997-08-12 01:05:41 UTC
Raw Date: Tue, 12 Aug 1997 09:05:41 +0800
From: "Dave Ross" <davros@raf.com>
Date: Tue, 12 Aug 1997 09:05:41 +0800
To: <cypherpunks@toad.com>
Subject: Fw: slow network behavior with Linux kernel 2.0.x
Message-ID: <m0wy50o-000sS8C@fred.raf.com>
MIME-Version: 1.0
Content-Type: text/plain
Can any of you help us with this mess? Linux is not my strong suit.
Thanks! My engineer is pulling his hair out. I would appreciate any
suggestions anyone could make.
-dave ross
davros@raf.com
----------
> From: Bruce Thompson <bt@raf.com>
> To: davros@fred
> Subject: Fw: slow network behavior with kernel 2.0.x
> Date: Tuesday, August 12, 1997 12:18 AM
>
>
>
> ----------
> | From: Bruce Thompson <bt@raf.com>
> | To: linux-kernel@vger.rutgers.edu
> | Cc: linux-net@vger.rutgers.edu
> | Subject: slow network behavior with kernel 2.0.x
> | Date: Thursday, July 31, 1997 4:40 PM
> |
> |
> | My company developes a psuedo real-time client-server system that runs
on
> | linux connected through TCP sockets. I have been noticing it has been
> | taking the data packets quite a while to reach the clients from the
> server.
> | After trying several different ethernet cards and speeds (TP vs
> thinnet,10
> | vs 100), I have determined that the slow down only occures when the
> server
> | is running with a linux 2.0.x kernel (I have not tried 2.1.x). Any
> system
> | running up to 1.3.89 runs fine at full speed. I have not yet tested any
> | kernel between 1.3.89 and 2.0.0
> |
> | From looking at tcpdumps, it appears that packets are not getting acked
> in
> | a timely way. I have turned off the 'delayed ack' feature of TCP and
> have
> | not seen any improvement. Here are some tcpdumps
> |
> |
> | Example of what I would expect to be normal.
> | 10:42:17.70 server > client: . 1:1461(1460) ack 98 win 31744 (DF)
> | 10:42:17.70 server > client: . 1461:2921(1460) ack 98 win 31744 (DF)
> | 10:42:17.71 client > server: . ack 2921 win 31744 (DF)
> | 10:42:17.71 server > client: . 2921:4381(1460) ack 98 win 31744
> | 10:42:17.71 server > client: . 4381:5841(1460) ack 98 win 31744
> | 10:42:17.71 server > client: . 5841:7301(1460) ack 98 win 31744
> | 10:42:17.72 client > server: . ack 7301 win 31744 (DF)
> | 10:42:17.72 server > client: P 7301:8760(1459) ack 98 win 31744 (DF)
> | 10:42:17.74 client > server: . ack 8760 win 31744 (DF)
> |
> | Example of time lost with no ack of the first packet causing a 200ms
> delay,
> | and two acks that cause waits of 40ms and 70ms.
> |
> | 10:42:22.17 server > client: . 8760:10220(1460) ack 1222 win 31744 (DF)
> | 10:42:22.37 server > client: . 8760:10220(1460) ack 1222 win 31744 (DF)
> | 10:42:22.37 client > server: . ack 10220 win 31744 (DF)
> | 10:42:22.37 server > client: . 10220:11680(1460) ack 1222 win 31744
> | 10:42:22.51 client > server: . ack 11680 win 31744 (DF)
> | 10:42:22.51 server > client: . 11680:13140(1460) ack 1222 win 31744
> | 10:42:22.51 server > client: . 13140:14600(1460) ack 1222 win 31744
> | 10:42:22.52 client > server: . ack 14600 win 31744 (DF)
> | 10:42:22.52 server > client: . 14600:16060(1460) ack 1222 win 31744
> | 10:42:22.59 client > server: . ack 16060 win 31744 (DF)
> | 10:42:22.59 server > client: P 16060:17519(1459) ack 1222 win 31744
(DF)
> | 10:42:22.61 client > server: . ack 17519 win 31744 (DF)
> |
> | Here is a particularly bad example where the same 8760 byte file took
1.7
> | seconds to be transfered.
> |
> | 10:17:14.95 server > client: . 1:1461(1460) ack 98 win 31744 (DF)
> | 10:17:15.14 client > server: . ack 1461 win 31744 (DF)
> | 10:17:15.14 server > client: . 1461:2921(1460) ack 98 win 31744
> | 10:17:15.14 server > client: . 2921:4381(1460) ack 98 win 31744
> | 10:17:15.44 client > server: . ack 2921 win 31744 (DF)
> | 10:17:15.44 server > client: . 4381:5841(1460) ack 98 win 31744
> | 10:17:15.45 client > server: . ack 2921 win 31744 (DF)
> | 10:17:15.64 client > server: . ack 2921 win 31744 (DF)
> | 10:17:16.08 server > client: . 2921:4381(1460) ack 98 win 31744
> | 10:17:16.27 client > server: . ack 5841 win 31744 (DF)
> | 10:17:16.27 server > client: . 5841:7301(1460) ack 98 win 31744
> | 10:17:16.57 client > server: . ack 7301 win 31744 (DF)
> | 10:17:16.57 server > client: P 7301:8760(1459) ack 98 win 31744 (DF)
> | 10:17:16.59 client > server: . ack 8760 win 31744 (DF)
> |
> | In general, the system just seems to be slow in responding to this
> network
> | traffic. This is a private network for these systems so there should
be
> | now problem with other traffic affecting these timings. With 1.3.x I
see
> | total transit times on the order of 30ms on the 10Mbps network.
> |
> | The same hardware that runs slowly with 2.0.x will run quickly with
only
> | the kernel changed.
> |
> | Any ideas as to what could be causing this?
> |
> |
> | Thanks,
> | -------------------------
> | Bruce Thompson
> | RAF Technology
> | (206) 867-0700
> |
> |
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1997-08-12 (Tue, 12 Aug 1997 09:05:41 +0800) - Fw: slow network behavior with Linux kernel 2.0.x - “Dave Ross” <davros@raf.com>