linux-kernel - Re: TSC not updating after resume: Bug or Feature?

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Message-Id: <200812182319.57235.rjw@sisk.pl>
Date:	Thu, 18 Dec 2008 23:19:56 +0100
From:	"Rafael J. Wysocki" <rjw@...k.pl>
To:	Ingo Molnar <mingo@...e.hu>
Cc:	Peter Zijlstra <peterz@...radead.org>,
	Steven Rostedt <srostedt@...hat.com>, dsaxena@...xity.net,
	Thomas Gleixner <tglx@...utronix.de>,
	linux-kernel@...r.kernel.org,
	Dave Kleikamp <shaggy@...ux.vnet.ibm.com>
Subject: Re: TSC not updating after resume: Bug or Feature?

On Thursday, 18 of December 2008, Ingo Molnar wrote:
> 
> * Peter Zijlstra <peterz@...radead.org> wrote:
> 
> > Rafael, would something like this explain why we had to revert Shaggy's 
> > patch?

Well, I have yet to understand what the suspend-resume of the timekeeping code
actually does.

The original description sounds worrisome to me, it looks like we've overlooked
something at least.

> > His patch fixes the backward motion filter and I'm at an utter  
> > loss why that would break suspend.
> 
> yes, i'd love to have this commit reinstated:
> 
>  5b7dba4: sched_clock: prevent scd->clock from moving backwards
> 
> and the bug triggered by hibernation fixed instead.

Shaggy said he had an idea of what was wrong, so I expect an updated version
of the patch to appear.

Thanks,
Rafael
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