linux-kernel - Re: [RFC][PATCH] Dynamic Tick: Allow 32-bit machines to sleep for more than 2.15 seconds

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Date:	Tue, 21 Apr 2009 13:32:16 -0700
From:	john stultz <johnstul@...ibm.com>
To:	Ingo Molnar <mingo@...e.hu>
Cc:	Jon Hunter <jon-hunter@...com>,
	Thomas Gleixner <tglx@...utronix.de>,
	"linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>
Subject: Re: [RFC][PATCH] Dynamic Tick: Allow 32-bit machines to sleep for
 more than 2.15 seconds

On Tue, 2009-04-21 at 08:35 +0200, Ingo Molnar wrote:
> * Jon Hunter <jon-hunter@...com> wrote:
> > Anyway, making this change has allowed my 32-bit machine to sleep 
> > for longer than ~2.15 seconds and thought this could be of 
> > interest to others. Your comments/feedback would be appreciated.
> >
> Looks like a good thing at first sight. Thomas, John, what do you 
> think?

The concern is many clocksources wrap after a handful of seconds. The
acpi_pm is the best example (its only 24 bits wide). 

I brought this issue up earlier, and provided some example code that
could be used to limit the idle time appropriately for the current
clocksource here:

http://lkml.indiana.edu/hypermail/linux/kernel/0901.3/02693.html

Jon: Did you see that mail, or is there a reason you didn't adapt this
code into your patch? 


thanks
-john


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