Date: Sun, 19 Sep 1999 22:59:55 +0200 From: Poul-Henning Kamp <phk@critter.freebsd.dk> To: David Scheidt <dscheidt@enteract.com> Cc: smp@freebsd.org, current@freebsd.org Subject: Re: Testers please! Message-ID: <18307.937774795@critter.freebsd.dk> In-Reply-To: Your message of "Sun, 19 Sep 1999 15:49:08 CDT." <Pine.NEB.3.96.990919154840.35740A-100000@shell-3.enteract.com>
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In message <Pine.NEB.3.96.990919154840.35740A-100000@shell-3.enteract.com>, 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 phk@FreeBSD.ORG "Real hackers run -current on their laptop." FreeBSD -- It will take a long time before progress goes too far! To Unsubscribe: send mail to majordomo@FreeBSD.org with "unsubscribe freebsd-smp" in the body of the message
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