From: Arjan van de Ven <arjan@infradead.org>
To: Pavel Machek <pavel@ucw.cz>
Cc: kernel list <linux-kernel@vger.kernel.org>,
mingo@redhat.com, Andrew Morton <akpm@osdl.org>
Subject: Re: 2.6.19-rc4-mm1: noidlehz problems
Date: Wed, 01 Nov 2006 14:02:57 +0100 [thread overview]
Message-ID: <1162386177.23744.17.camel@laptopd505.fenrus.org> (raw)
In-Reply-To: <20061101122319.GA13056@elf.ucw.cz>
On Wed, 2006-11-01 at 13:23 +0100, Pavel Machek wrote:
> Hi!
>
> First, it would be nice if we had someone listed as a maintainer of
> noidlehz stuff...
>
> Then... I'm getting strange messages from noidlehz each time I
> unplug/replug AC power (perhaps due to interrupt latency?).
there probably is a different story going on.
When you unplug/replug AC power, several bioses change the meaning of
the software C-states in your system.
(there is a mapping between software visible C states and the hardware
C-states)
In some (hardware) C-states, the local apic timer stops (as does the
TSC), while in others it keeps running. If you change from AC to
battery, the bios can change the meaning of a software C-state from one
where local apic timer keeps going to one where it stops. This obviously
upsets the hrtimers/tickless code since that uses local apic timer for
event generation....
--
if you want to mail me at work (you don't), use arjan (at) linux.intel.com
Test the interaction between Linux and your BIOS via http://www.linuxfirmwarekit.org
next prev parent reply other threads:[~2006-11-01 13:03 UTC|newest]
Thread overview: 6+ messages / expand[flat|nested] mbox.gz Atom feed top
2006-11-01 12:23 Pavel Machek
2006-11-01 12:55 ` Pavel Machek
2006-11-01 13:02 ` Arjan van de Ven [this message]
2006-11-01 13:20 ` Pavel Machek
2006-11-01 15:22 ` Matthew Garrett
2006-11-01 20:55 ` Thomas Gleixner
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