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Date:      Wed, 27 Feb 2002 16:26:35 -0800
From:      "Frost, Stephen C" <stephen.c.frost@intel.com>
To:        "'freebsd-questions@freebsd.org'" <freebsd-questions@freebsd.org>, "'freebsd-hackers@freebsd.org'" <freebsd-hackers@freebsd.org>
Subject:   FreeBSD, SMP and Performance Speeds?
Message-ID:  <B9ECACBD6885D5119ADC00508B68C1EA0288A6E1@orsmsx107.jf.intel.com>

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All -

I have RTFM'd, with little luck.  Can some enlightened soul impart knowledge
upon me, thus letting me know why any kernels compiled with SMP enabled seem
to be slowing the whole system down?  Throughput goes down by 40%.  Tasks
take twice as long to run, etc, etc...

I have multiple boxes (Dells, IBM's, Microns, Gateways...) running FreeBSd
4.5, all showing the same phenomenon.  I initially mistook it for a NIC
driver issue, but it appears to be system-wide.  And is directly linked to
SMP: two kernels, identical EXCEPT that one has SMP enabled, the other not.
The enabled kernel that *should* be fully utilizing multi-procs is suddenly
effectively running at half speed.

Is this a config issue?  Any helpful hints?  Or is it better just to keep
SMP disabled on a multi-proc box?

Your adult supervision is appreciated.

Thanks -

    -=C. Stephen Frost=-
       Intel Corp.
       ICG - Network Quality Labs
       Software Test Engineer
       503.264.8300

All opinions are my own and other standard disclaimers...


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