Odd performance problems after upgrade from 4.11 to 6.0-Stable
Jonathan Noack
noackjr at alumni.rice.edu
Wed Dec 14 18:02:05 PST 2005
Scott Long wrote:
> Also, taking out CPU_I586 is usually a bad idea. It offers no
> performance penalties (unlike CPU_I386 and maybe CPU_I486), but
> enables things like optimized bcopy.
Is that documented? In /sys/i386/conf/NOTES I see:
# You must specify at least one CPU (the one you intend to run on);
# deleting the specification for CPUs you don't need to use may make
# parts of the system run faster.
#
cpu I486_CPU
cpu I586_CPU # aka Pentium(tm)
cpu I686_CPU # aka Pentium Pro(tm)
I've always commented out I486_CPU and I586_CPU. Shouldn't leaving in
I686_CPU enable all the features it can use? Do you mean I've spent all
these years using un-optimized bcopy?!?
-Jonathan
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