Re: FreeBSD -> Windows HTTP TCP performance

From: CHOI Junho (cjh_at_kr.FreeBSD.org)
Date: 01/15/04

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    Date: Fri, 16 Jan 2004 00:04:01 +0900 (KST)
To: andre@freebsd.org

    From: Andre Oppermann <andre@freebsd.org>
    Subject: Re: FreeBSD -> Windows HTTP TCP performance
    Date: Thu, 15 Jan 2004 15:30:23 +0100

    > CHOI Junho wrote:
    > >
    > > For those who interested, I made packet dump file:
    > >
    > > http://www.kr.freebsd.org/~cjh/misc/freebsd-net/
    > >
    > > Best thing is do tcpdump at client machine but I have no admin
    > > permission, so failed.
    >
    > I can't read the dump files with ethereal, it says they are corrupt.

    > file *.tcpdump
    test-fbsd.tcpdump: tcpdump capture file (little-endian) - version 2.4 (Ethernet, capture length 120)
    test-w2k.tcpdump: tcpdump capture file (little-endian) - version 2.4 (Ethernet, capture length 120)

    I can read these files with 'tcpdump -r <file>'. They are captured
    with 'tcpdump -w <file> -p -v -s 120 -n -l host <ip>'.
     
    > But lets go through your sysctl settings:
    >
    > > kern.clockrate: { hz = 2000, tick = 500, ...
    >
    > HZ should not be higher than 1000 or you get problems with some
    > tcp timers.

    OK.

    > > kern.ipc.maxsockbuf: 67108864
    >
    > This is way too high. Normally it is 262144 (=256k). Don't do
    > more than 1MByte.

    OK.

    > > <118>Jan 12 13:06:21 kt-down3 thttpd[37449]: accept - Software caused connection abort
    > > <118>Jan 12 13:21:00 kt-down3 thttpd[37449]: mmc panic - freeing 49 unreferenced maps
    > > <118>Jan 12 13:22:49 kt-down3 thttpd[37449]: mmc panic - freeing 49 unreferenced maps
    > > <118>Jan 12 13:31:18 kt-down3 thttpd[37449]: mmc panic - freeing 45 unreferenced maps
    > > <118>Jan 12 13:33:12 kt-down3 thttpd[37449]: mmc panic - freeing 110 unreferenced maps
    >
    > This doesn't look good. You should find out why thttpd is complaining.

    This thttpd is my custom version... it is some kind of
    debugging(periodical garbage collection).

    > > net.inet.tcp.sendspace: 32768
    > > net.inet.tcp.recvspace: 16384
    >
    > It's better to have them both at 65536 (64k).

    OK.

    > > net.inet.tcp.delayed_ack: 0
    >
    > It's better to have this turned on.

    Some people or webpage recommends turning off delayed_ack for Windows
    clients. Which is true?

    > > net.inet.tcp.slowstart_flightsize: 1
    >
    > You can raise this to 4.

    OK.

    > > net.inet.tcp.msl: 1000
    >
    > It's better to have this at 30000.

    OK.

    > You should change these values and try again. A new tcpdump would be
    > helpful too.

    Thank you! I'll try with new tuned parameters. 

    --
CHOI Junho <http://www.kr.FreeBSD.org/~cjh>     KFUG <cjh at kr.FreeBSD.org>
FreeBSD Project <cjh at FreeBSD.org>        Web Data Bank <cjh at wdb.co.kr>
Key fingerprint = 1369 7374 A45F F41A F3C0  07E3 4A01 C020 E602 60F5
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