Re: 486DLC Tuning

From: Peter Jeremy <PeterJeremy_at_optushome.com.au>
Date: Sun, 16 Oct 2005 08:45:47 +1000
On Sat, 2005-Oct-15 10:06:22 -0400, Joshua Coombs wrote:
>I have a 386 with a Cyrix 486DRx2-66 (clock doubled DLC) that I moved 
>from 4.11 to 6.0.  So far it's running decently, I've got more net/hd 
>throughput than I had before, by a factor of two for net, but the box 
>'feels' like I'm not getting the same cpu perf I had before.  Without 
>benchmarks, I'm not in the best position to prove it, but I figured 
>I'd try some basic tuning to see if I could improve things.

I suspect your box would be happier running 4.x than 6.x

>machine         i386
>cpu             I386_CPU
>cpu             I486_CPU

According to NOTES:
# I386_CPU is mutually exclusive with the other CPU types.
# I386_CPU is deprecated and will be removed in 6.0-RELEASE.

>It seems odd that I can have CYRIX_CACHE_REALLY_WORKS but not 
>CYRIX_CACHE_WORKS enabled.

This code only functionally affects src/sys/i386/i386/initcpu.c (though
CYRIX_CACHE_REALLY_WORKS also disables a 'CPU cache:' message).  There
has been no change in this code between 4-STABLE and 7-CURRENT.

All I can suggest is for you to study the code in conjunction with a
Cyrix system programming manual to understand what the effect of the
options is.

-- 
Peter Jeremy
Received on Sat Oct 15 2005 - 20:45:53 UTC

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