From owner-freebsd-questions  Wed May 16 11:29: 8 2001
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Date: Wed, 16 May 2001 13:29:03 -0500 (CDT)
From: Dave Leimbach <dleimbac@MPI-Softtech.Com>
Reply-To: Dave Leimbach <dleimbac@MPI-Softtech.Com>
Subject: Huge difference in kernel reconfig.
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I reconfigured my kernel from the default which has apm turned on to disabling 
apm on my desktop at home and I got a huge performance improvement in my code 
which uses gettimeofday calls.  

Needless to say each call went from 6.7xx usec to .7 usec per gettimeofday.
(almost 10x faster)

The difference is whether or not you use TSC and apm enabled = TSC disabled.

Now the question is why can't apm and TSC co-exist? they do on other platforms.  
 It also means if I were to use apm in a place where its truly useful/needed I 
cannot use TSC.

Is this a design constraint?

Dave


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