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    SubjectRE: threading question

    On 12-Jun-2001 wrote:
    > Hello,
    > I am a summer student implementing a multi-threaded version of a very
    > popular bioinformatics tool. So far it compiles and runs without problems
    > (as far as I can tell ;) on Linux 2.2.x, Sun Solaris, SGI IRIX and Compaq
    > OSF/1 running on Alpha. I have ran a lot of timing tests compared to the
    > sequential version of the tool on all of these machines (most of them are
    > dual-CPU, although I am also running tests on 12-CPU Solaris and 108 CPU
    > SGI IRIX). On dual-CPU machines the speedups are as follows: my version
    > is 1.88 faster than the sequential one on IRIX, 1.81 times on Solaris,
    > 1.8 times on OSF/1, 1.43 times on Linux 2.2.x and 1.52 times on Linux 2.4
    > kernel. Why are the numbers on Linux machines so much lower? It is the
    > same multi-threaded code, I am not using any tricks, the code basically
    > uses PTHREAD_CREATE_DETACHED and PTHREAD_SCOPE_SYSTEM and the thread stack
    > size is set to 8K (but the numbers are the same with larger/smaller stack
    > sizes).
    > Is there anything I am missing? Is this to be expected due to Linux way of
    > handling threads (clone call)? I am just trying to explain the numbers and
    > nothing else comes to mind....

    How is your vmstat while your tool is running ?

    - Davide

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