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:
>>
>> http://phk.freebsd.dk/piix/
>>
>> 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:
New:
sysctl -w kern.timecounter.hardware=PIIX
(if it refuses you probably don't have the PIIX4 hardware)
Old:
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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