Date: Wed, 24 Nov 2010 14:00:24 GMT From: Andriy Gapon <avg@freebsd.org> To: freebsd-amd64@FreeBSD.org Subject: Re: amd64/152405: wrong user time is reported when CPU frequency throttled. Message-ID: <201011241400.oAOE0ONA093305@freefall.freebsd.org>
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The following reply was made to PR amd64/152405; it has been noted by GNATS. From: Andriy Gapon <avg@freebsd.org> To: =?UTF-8?B?IktPSUUgSGlkZXRha2EgKOmvieaxn+iLsemahu+8oOaVsOeQhuaKgOeglCki?= <koie@suri.co.jp> Cc: bug-followup@freebsd.org Subject: Re: amd64/152405: wrong user time is reported when CPU frequency throttled. Date: Wed, 24 Nov 2010 15:54:19 +0200 on 24/11/2010 14:33 KOIE Hidetaka (鯉江英隆＠数理技研) said the following: > | Can you try to boot with kern.eventtimer.timer="i8254" in loader.conf? > > Boot process hangs up. (I tried 2 times) Oh, hm, very strange. Not sure why that happens. Anyway, it seems that I missed the real cause of this problem and the excellent explanation by Bruce. Your CPU doesn't have invariant TSC and (x86) FreeBSD doesn't handle that correctly for some things like e.g. CPU time accounting that you are reporting about. This is not a problem for modern hardware which almost universally supports invariant TSC, but older models are affected. -- Andriy Gapon
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