From owner-freebsd-smp Sun Sep 19 14: 0:38 1999 Delivered-To: freebsd-smp@freebsd.org Received: from critter.freebsd.dk (critter.freebsd.dk [212.242.40.131]) by hub.freebsd.org (Postfix) with ESMTP id DB05D14BCD; Sun, 19 Sep 1999 14:00:34 -0700 (PDT) (envelope-from phk@critter.freebsd.dk) Received: from critter.freebsd.dk (localhost [127.0.0.1]) by critter.freebsd.dk (8.9.3/8.9.2) with ESMTP id WAA18309; Sun, 19 Sep 1999 22:59:55 +0200 (CEST) (envelope-from phk@critter.freebsd.dk) To: David Scheidt Cc: smp@freebsd.org, current@freebsd.org Subject: Re: Testers please! In-reply-to: Your message of "Sun, 19 Sep 1999 15:49:08 CDT." Date: Sun, 19 Sep 1999 22:59:55 +0200 Message-ID: <18307.937774795@critter.freebsd.dk> From: Poul-Henning Kamp Sender: owner-freebsd-smp@FreeBSD.ORG Precedence: bulk X-Loop: FreeBSD.org In message , 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