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From: Pete French <petefrench@ticketswitch.com>
Date: Mon, 09 May 2005 18:31:19 +0100
cc: freebsd-stable@freebsd.org
Subject: Re: Performance issue
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> 5.3 ships with SMP turned on, which makes lock operations rather 
> expensive on single-processor machines.  4.x does not have SMP
> turned on by default.  Would you be able to re-run your test with
> SMP turned off?

I just ran a test here with SMP turned of on 5.4-RC4 (GENERIC) I got the
following result:

       67.52 real        41.13 user        26.16 sys
      7034  involuntary context switches

i.e. it still has system time a a huge proportion of the total compared
to the 4.11 kernel. Interesingly, after reading Holger Kipp's results
I tried it on a genuine multi-processor box with SMP enabled running 5.3.
He got a very small percentage of the time in sys (3.51 out of 81.90) but
I got:
      255.30 real       160.20 user        88.50 sys

Once again a far higher proprtion of the time spent in sys than you would
expect.

-pcf.