Scheduling problems

From: Chris Boot (bootc_at_bootc.net)
Date: 05/07/04

  • Next message: Toby Batch: "Re: Imapd trouble" 
    To: debian-user@lists.debian.org
Date: Fri, 7 May 2004 14:22:50 +0100

    Hi,

    I'm having several problems concerning scheduling on my linux box. I'm
    running it as a server and therefore I'd like it to be as reliable as
    possible, but several niggling factors force me to reboot the box
    relatively often.

    The biggest problem I have is if there is no CPU idle time (as reported
    by top(1)) processes take a very long time to start up, and sometimes
    even fail to start entirely. I can trigger this very easily and it is
    very reproducible. I tried to run the Distributed.net client at some
    point but it ground my system to a halt (even nice'd to 19). This
    prevents me from logging in using SSH to kill the offending process, or
    checking my email, or any other task that requires starting processes.

    The next biggest problem is related to the above, I think. When I
    connect to my box using SSH, and the connection is broken somehow, the
    SSHd process takes up all the available CPU after just a couple of
    seconds. All I need to do to trigger this is to connect to the server,
    then kill the SSH client process. After a few seconds, the server
    process reaches 99.9% CPU usage:

    [bootc@arcadia bootc]$ pa | grep notty
    bootc 24408 99.9 0.4 10688 3928 ? R 14:15 0:38 sshd:
    bootc@notty
    bootc 24448 0.0 0.0 1576 496 pts/7 S+ 14:16 0:00 grep
    notty

    I'm running Debian Sarge on Linux 2.6.5 with no special patches. The
    machine is a Shuttle XPC with an Athlon XP2000+ and 1GB of RAM. The
    problems have occurred for as long as I can remember, definitely all
    along the 2.6 kernel series, but most probably before then too.

    Thanks for any pointers people can give me...

    Regards,
    Chris 

    -- 
Chris Boot
bootc@bootc.net
http://www.bootc.net/
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