In message <[EMAIL PROTECTED]>, Dav
id Scheidt writes:
>On Sun, 19 Sep 1999, Poul-Henning Kamp wrote:
>> If you have a PIIX4 based SMP system and run current, could you
>> please try out this patch:
>> I'm very interested in hearing if there are any measurable difference
>> apart from clock granularity being 3 times better.
>What sort of tests would you like done before and after?

Any test you can think of really.

I don't expect any problems, but I am very interested in the
performance difference if any, since that would give me a good
indication if it is a worthwhile job to spend more time on
obfuscat^H^H^H^H^H^H^Hptimizing the timecounter code.

As far as I can tell, access to the PIIX timecounter is about 2.5
microseconds faster than to the i8254.  In relative terms it is
about a factor 3 faster.

You can flip forth and back between the old and new behaviour with:

        sysctl -w kern.timecounter.hardware=PIIX

(if it refuses you probably don't have the PIIX4 hardware)

        sysctl -w kern.timecounter.hardware=i8254

Poul-Henning Kamp             FreeBSD coreteam member
[EMAIL PROTECTED]               "Real hackers run -current on their laptop."
FreeBSD -- It will take a long time before progress goes too far!

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