From: Linus Torvalds <torvalds@linux-foundation.org>
To: Larry Finger <Larry.Finger@lwfinger.net>
Cc: Thomas Gleixner <tglx@linutronix.de>,
LKML <linux-kernel@vger.kernel.org>,
"Rafael J. Wysocki" <rjw@sisk.pl>,
Alok Kataria <akataria@vmware.com>, Michael Buesch <mb@bu3sch.de>
Subject: Re: Regression in 2.6.27 caused by commit bfc0f59
Date: Mon, 1 Sep 2008 11:42:38 -0700 (PDT) [thread overview]
Message-ID: <alpine.LFD.1.10.0809011136340.12958@nehalem.linux-foundation.org> (raw)
In-Reply-To: <48BC2A03.9000104@lwfinger.net>
On Mon, 1 Sep 2008, Larry Finger wrote:
>
> TSC calibrated against PIT
> Detected 428.823 MHz processor.
Ok, Thomas, that means that the PIT is reliable (not surprising), and the
PM_TIMER isn't (again, I'm not horribly surprised). And HPET isn't
available, of course.
The old x86-32 code never even bothered with the PM_TIMER for calibration.
I don't understand why the x86-64 code bothers with it either. Why not
just drop that whole broken thing, and just depend on the PIT if there is
no HPET?
I would also like to point out that the 32-bit code actually had a much
nicer PIT setup, using the much better documented mach_prepare_counter()
and mach_countup() helper functions. I'm unhappy to note that the new
"common" code uses what appears to be the inferior code.
Also, note that this is _not_ a new issue. See "verify_pmtmr_rate()" in
drivers/clocksource/acpi_pm.c, along with all the code to check that the
reads are stable in "init_acpi_pm_clocksource()".
IOW, the PM_TIMER has been found to be broken before. Depending on it for
calibration is broken.
Linus
next prev parent reply other threads:[~2008-09-01 18:43 UTC|newest]
Thread overview: 56+ messages / expand[flat|nested] mbox.gz Atom feed top
2008-08-31 22:54 Larry Finger
2008-09-01 11:14 ` Thomas Gleixner
2008-09-01 15:37 ` Larry Finger
2008-09-01 17:49 ` Thomas Gleixner
2008-09-01 17:44 ` Larry Finger
2008-09-01 18:31 ` Thomas Gleixner
2008-09-01 19:10 ` Linus Torvalds
2008-09-01 20:07 ` Thomas Gleixner
2008-09-01 21:30 ` Thomas Gleixner
2008-09-01 22:02 ` Linus Torvalds
2008-09-01 22:33 ` Thomas Gleixner
2008-09-01 22:56 ` Linus Torvalds
2008-09-01 23:24 ` Thomas Gleixner
2008-09-02 6:37 ` Andi Kleen
2008-09-02 12:21 ` Thomas Gleixner
2008-09-01 22:16 ` Linus Torvalds
2008-09-01 23:16 ` Thomas Gleixner
2008-09-02 3:18 ` Linus Torvalds
2008-09-02 3:35 ` Linus Torvalds
2008-09-02 4:54 ` Larry Finger
2008-09-02 9:17 ` Alan Cox
2008-09-02 12:15 ` Thomas Gleixner
2008-09-02 15:09 ` Linus Torvalds
2008-09-02 18:14 ` Thomas Gleixner
2008-09-02 18:41 ` Alok Kataria
2008-09-02 21:16 ` Thomas Gleixner
2008-09-02 18:42 ` Linus Torvalds
2008-09-02 21:13 ` Thomas Gleixner
2008-09-02 22:21 ` Linus Torvalds
2008-09-02 23:10 ` Thomas Gleixner
2008-09-03 1:49 ` Linus Torvalds
2008-09-02 22:54 ` [PATCH] Fix TSC calibration issues Thomas Gleixner
2008-09-03 2:14 ` Linus Torvalds
2008-09-03 9:11 ` Thomas Gleixner
2008-09-04 1:14 ` Alok Kataria
2008-09-04 2:56 ` Linus Torvalds
2008-09-04 3:16 ` Arjan van de Ven
2008-09-04 3:59 ` Linus Torvalds
2008-09-04 4:10 ` Arjan van de Ven
2008-09-04 4:20 ` Linus Torvalds
2008-09-04 4:27 ` Arjan van de Ven
2008-09-04 4:25 ` Willy Tarreau
2008-09-04 4:53 ` Linus Torvalds
2008-09-04 5:09 ` Willy Tarreau
2008-09-04 1:18 ` [PATCH] Change warning message in TSC calibration Alok Kataria
2008-09-03 2:51 ` [PATCH] Fix TSC calibration issues Larry Finger
2008-09-03 4:00 ` Linus Torvalds
2008-09-03 4:34 ` Larry Finger
2008-09-05 13:45 ` Regression in 2.6.27 caused by commit bfc0f59 Mark Lord
2008-09-02 17:17 ` Bill Davidsen
2008-09-01 19:36 ` Larry Finger
2008-09-01 20:09 ` Thomas Gleixner
2008-09-01 20:23 ` Larry Finger
2008-09-01 20:45 ` Thomas Gleixner
2008-09-01 18:42 ` Linus Torvalds [this message]
2008-09-01 19:08 ` Thomas Gleixner
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