Re: Benchmarking kqueue() performance?

From: Terry Lambert (tlambert2_at_mindspring.com)
Date: 10/18/03

  • Next message: Bruce M Simpson: "Re: sshd source code" 
    Date: Fri, 17 Oct 2003 22:03:42 -0700
To: Lev Walkin <vlm@netli.com>

    Lev Walkin wrote:
    > One of the most comprehensive sites about that problem is:
    >
    > http://www.kegel.com/c10k.html

    That's about scaling to a large number of connections, not about
    kqueue() vs. select performance.

    The biggest problem with a large number of connections, at least
    as far as FreeBSD is concerned, is the TCP timer implementation
    using a callout wheel, since any expiring timer has to traverse
    every bucket in the chain, instead of stopping at the first one
    that's un expired (see the BSD 4.2/4.3 timers for an example of
    the right way to do it).

    FWIW: I've had a FreeBSD box with a static page server on it up
    to 1.6M simultaneous connections with very little work, so 10K
    is pretty trivial in comparison.

    For doing real work, and giving 1G to a server process and 512M
    to caching, this number drops to ~250K connections, but that's
    still 25 time what he claims is some insurmountable barrier.

    BTW, the company for which I did this work is still shipping
    real product that handles those loads on a FreeBSD box, FWIW.

    -- Terry
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  • Next message: Bruce M Simpson: "Re: sshd source code"

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