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  1. #1
    Join Date
    May 2003
    my modem

    Angry load average with dual core cpu

    i have a server with this specs:

    Pentium4 2.8GHz DC
    2048 Mb RAM
    250 GB SATA x 2

    CentOS as operating system.

    What's the problem? I'm running some services that requires load average less than 1.00. Today support told me that 0.00 - 2.00 is a normal load average for a dual processor. I don't agree with this answer.

    What's your opinion?

    Thank you.

  2. #2
    Join Date
    Jun 2003
    0-2.00 is reasonable for a Dual Core system ( see for more info ) Basically a load of 2.00 means the CPU is 100% busy if everything is CPU bound. I think your software needs to have that limit thing changed though as quite often servers will run above 1.00 even if single cores
    Russ Foster - Industry Curmudgeon

  3. #3
    Join Date
    Jun 2004
    Bay Area
    A load of 2 is absolutely fine for a dual core system.
    Basically a load of 2.00 means the CPU is 100% busy if everything is CPU bound.
    As far as I know the load does not need to be generated by the CPU. You could have a load of 2 due to high IO usage, and still only use 5% CPU

  4. #4

    Let me explain load averages

    The load average is not reliable enough of a metric to judge whether your server is able to do more work than it currently is doing. A dual-proc web server with a load of 4.00 is probably fine. My single-proc web server commonly runs at a load of 8.00 without much loss in responsiveness.

    If a dual-proc server has a load of 2.00, it simply means that any new work that comes along (usuaully a new connection from a client machine) won't be processed immediately but will have to wait through the current run queue. If your dual-proc server has a load of 4.00, any new connection is going to have to wait for at least 1 task to complete. I think Linux timeslices are ~10ms, so to estimate the wait time for a new connection, use this formula:

    WaitTime = Load / N-proc * 10ms

    Google "unix load lifeaftercoffee" and you will find a good blog post talking about this (sorry, I'm a new user, I can't post URLs yet).

    Also, don't use the "top" program to monitor your load as it will increase load substantially. Instead use the "uptime" command.

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