From: Linus Torvalds <torvalds@linux-foundation.org>
To: Jesper Krogh <jesper@krogh.cc>
Cc: john stultz <johnstul@us.ibm.com>,
Thomas Gleixner <tglx@linutronix.de>,
Linux Kernel Mailing List <linux-kernel@vger.kernel.org>,
Len Brown <len.brown@intel.com>
Subject: Re: Linux 2.6.29-rc6
Date: Mon, 9 Mar 2009 21:26:48 -0700 (PDT) [thread overview]
Message-ID: <alpine.LFD.2.00.0903092109460.19207@localhost.localdomain> (raw)
In-Reply-To: <49B57F3D.5030008@krogh.cc>
On Mon, 9 Mar 2009, Jesper Krogh wrote:
>
> First boot.
> [ 0.000000] ref_freq: 2311825 pit_freq: 2310386
> Second boot:
> [ 0.000000] ref_freq: 2311803 pit_freq: 2310190
> Third boot:
> [ 0.000000] ref_freq: 2311824 pit_freq: 2310080
> Fourth boot:
> [ 0.000000] ref_freq: 2311831 pit_freq: 2310130
It's really quite impressively stable, but the fast-PIT calibration
frequency is reliably about 3/4 of a promille low. Or, put another way,
the TSC difference over the pit calibration is just a _tad_ too small
compared to the value we'd expect if that loop of pit_expect_msb() would
really run at the expected delay of a 1.193182MHz clock divided by 256.
And it's stable in that it really always seems to be off by a very similar
amount. It's not moving around very much.
I also wonder why it seems to happen mainly just to _you_. There's
absolutely nothing odd in your system, neither a slow CPU or anything
else that would stand out.
Grr. Very annoyingly non-obvious.
Linus
next prev parent reply other threads:[~2009-03-10 4:27 UTC|newest]
Thread overview: 81+ messages / expand[flat|nested] mbox.gz Atom feed top
2009-02-23 4:31 Linux 2.6.29-rc6 Linus Torvalds
2009-02-23 14:07 ` Linux 2.6.29-rc6 - Fix oops in i915_gem_retire_requests Karsten Wiese
2009-02-26 11:15 ` Linux 2.6.29-rc6 Jesper Krogh
2009-02-26 17:17 ` MTD_CK804XROM warning (Was: Linux 2.6.29-rc6) Marcin Slusarz
2009-02-26 17:53 ` Linux 2.6.29-rc6 Linus Torvalds
2009-02-26 19:22 ` David Woodhouse
2009-02-26 19:31 ` Jesper Krogh
2009-02-26 19:36 ` David Woodhouse
2009-02-26 19:46 ` Jesper Krogh
2009-02-26 19:49 ` David Woodhouse
2009-02-26 20:53 ` Carl-Daniel Hailfinger
2009-02-26 20:32 ` Linus Torvalds
2009-02-26 19:55 ` Jesper Krogh
2009-02-26 20:33 ` Linus Torvalds
2009-02-26 20:43 ` Jesper Krogh
2009-02-26 21:19 ` john stultz
2009-02-26 21:35 ` Jesper Krogh
2009-02-26 21:46 ` john stultz
2009-02-26 21:54 ` Thomas Gleixner
2009-02-26 22:04 ` Jesper Krogh
2009-02-27 6:30 ` Jesper Krogh
2009-03-01 13:51 ` Jesper Krogh
2009-02-26 21:49 ` Linus Torvalds
2009-03-01 15:04 ` Jesper Krogh
2009-02-26 21:54 ` john stultz
2009-02-26 22:06 ` Thomas Gleixner
2009-02-26 22:24 ` Linus Torvalds
2009-02-26 22:31 ` Linus Torvalds
2009-02-26 22:31 ` john stultz
2009-02-26 22:40 ` Linus Torvalds
2009-02-26 22:59 ` john stultz
2009-02-27 7:33 ` Ingo Molnar
2009-02-27 20:50 ` john stultz
2009-02-27 6:47 ` Jesper Krogh
2009-02-27 20:35 ` john stultz
2009-03-01 20:13 ` Jesper Krogh
2009-03-02 9:53 ` Jesper Krogh
2009-03-02 21:27 ` john stultz
2009-03-03 6:04 ` Jesper Krogh
2009-03-03 19:53 ` john stultz
2009-03-03 20:19 ` Jesper Krogh
2009-03-03 22:22 ` john stultz
2009-03-04 15:30 ` Jesper Krogh
2009-03-04 18:36 ` Jesper Krogh
2009-03-04 18:57 ` John Stultz
2009-03-05 2:39 ` john stultz
2009-03-05 2:52 ` john stultz
2009-03-05 8:43 ` Ingo Molnar
2009-03-06 3:13 ` john stultz
2009-03-06 3:54 ` john stultz
2009-03-06 11:34 ` Ingo Molnar
2009-03-09 20:42 ` Jesper Krogh
2009-03-10 4:26 ` Linus Torvalds [this message]
2009-03-10 11:29 ` Thomas Gleixner
2009-03-10 19:42 ` Jesper Krogh
2009-03-10 22:22 ` Thomas Gleixner
2009-03-15 19:53 ` Jesper Krogh
2009-03-16 18:40 ` Jesper Krogh
2009-03-15 1:19 ` Linus Torvalds
2009-03-15 15:44 ` Jesper Krogh
2009-03-15 18:09 ` Linus Torvalds
2009-03-15 18:38 ` Jesper Krogh
2009-03-15 19:02 ` Linus Torvalds
2009-03-15 19:52 ` Jesper Krogh
2009-03-16 18:59 ` Jesper Krogh
2009-03-16 19:32 ` Linus Torvalds
2009-03-17 1:43 ` john stultz
2009-03-17 8:14 ` Ingo Molnar
2009-03-17 15:48 ` Linus Torvalds
2009-03-17 16:13 ` Ingo Molnar
2009-03-17 16:28 ` Linus Torvalds
2009-03-17 16:40 ` Ingo Molnar
2009-03-17 17:28 ` Olivier Galibert
2009-03-21 9:11 ` Jesper Krogh
2009-03-21 10:06 ` Ingo Molnar
2009-03-15 20:32 ` Linus Torvalds
2009-03-03 20:39 ` Jesper Krogh
2009-03-03 22:16 ` john stultz
2009-03-04 5:36 ` Jesper Krogh
2009-03-01 15:09 ` Jesper Krogh
2009-03-01 15:44 ` Linux 2.6.29-rc6 (clocksource) Sitsofe Wheeler
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