Re: iMac and FreeBSD performance problems

From: Barney Wolff (barney_at_databus.com)
Date: 10/31/03

  • Next message: David Carter-Hitchin: "Re: ppp link always dials when started with -auto?" 
    Date: Fri, 31 Oct 2003 01:35:14 -0500
To: Keith Mitchell <kmitch@guru.org>

    On Fri, Oct 31, 2003 at 01:01:17AM -0500, Keith Mitchell wrote:
    >
    > What I see is extremely slow transfers (FTP/TFTP at least) from the
    > FreeBSD machines to the iMac. The reverse direction (from the iMac to
    > the FreeBSD machiens work fine). If this isn't bad enough, if I connect
    > the iMac to a 10BT hub instead of the ethernet switch then everything
    > seems to work fine as well. The iMac can talk to all the other equipment
    > without a problem when its connected to the ethernet switch. Likewise
    > the FreeBSD machines can talk to each other without any problems and to
    > all of the other networking equipment.... they just can't talk to the iMac
    > efficiently.

    tcpdump is your friend. Run it in save-to-disk mode, then look at
    results at leisure. Run at both ends. I'd expect packet loss and
    retransmissions. The question is why.

    You can play with tuning parameters at both ends.
    Receive window size, MTU, (local_)slowstart_flightsize,
    path_mtu_discovery. MTU is settable by ifconfig, others by sysctl.
    Send to /dev/null to eliminate disk issues.
    Swap cables. Swap ports.
    Good luck. 

    -- 
Barney Wolff         http://www.databus.com/bwresume.pdf
I'm available by contract or FT, in the NYC metro area or via the 'Net.
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  • Next message: David Carter-Hitchin: "Re: ppp link always dials when started with -auto?"