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    SubjectRe: threading question

    On 12-Jun-2001 Christoph Hellwig wrote:
    > In article <Pine.LNX.4.30.0106121213570.24593-100000@gene.pbi.nrc.ca> you
    > wrote:
    >> 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?
    >
    > Does your measurement include the time needed to actually create the
    > threads or do you even frequently create and destroy threads?

    This is an extract of the most busy vmstat report running under his tool :

    12 0 0 15508 40980 24880 355480 0 0 0 0 141 481 100 0 0
    19 0 0 15508 40248 24880 355480 0 0 0 0 142 564 100 0 0
    12 0 0 15508 40112 24880 355480 0 0 0 0 150 543 100 0 0
    11 0 0 15508 41272 24880 355480 0 0 0 0 156 594 99 1 0
    17 0 0 15508 40408 24880 355480 0 0 0 0 156 474 99 1 0
    17 0 0 15508 39840 24880 355480 0 0 0 0 135 475 100 0 0
    21 0 0 15508 39568 24880 355480 0 0 0 0 125 409 100 0 0
    21 0 0 15508 39668 24880 355480 0 0 0 0 135 420 100 0 0
    16 0 0 15508 39760 24880 355480 0 0 0 0 149 486 100 0 0


    The context switch is very low and the user CPU utilization is 100% , I don't
    think it's system responsibility here ( clearly a CPU bound program ).
    Even if the runqueue is long, the context switch is low.
    I've just close to me a dual PIII 1GHz workstation that run an MTA that uses
    linux pthreads with context switching ranging between 5000 and 11000 with a
    thread creation rate of about 300 thread/sec ( relaying 600000 msg/hour ).
    No problem at all with the system even if the load avg is a bit high
    ( about 8 ).




    - Davide

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