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DragonFly kernel List (threaded) for 2004-04
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Re: pipe testing and kernel copyin/copyout/bcopy performance

From: Matthew Dillon <dillon@xxxxxxxxxxxxxxxxxxxx>
Date: Thu, 29 Apr 2004 13:34:14 -0700 (PDT)

:>     on optimizing the kernel bcopy, memcpy, copyin, and copyout to use
:>     XMM instructions when possible.
:Great!  How about SSE1 for us Athlon P4/Xeon users? :)  

    It will back down to MMX (64 bit) instructions if it only sees SSE1.

    The minimum requirement is MMX + SSE + FXSR.  The kernel reports
    which optimization (if any) it is using the dmesg output.  Search
    for 'MMX' or 'XMM'.

    But I don't have any P4/Xeon's, only a single UP P4 Celeron, so in
    fact I would be quite pleased if those people with an interest could
    do some playing around with the 'mem1' program in /usr/src/test/sysperf
    (just type 'make').  

    Note however that you have to manually edit which copy tests it does since
    it bus fault if you try to run the XMM (SSE2) test on a machine without
    SSE2 :-)


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