linux-kernel - Re: [PATCH 1/2] Dynamic Tick: Prevent clocksource wrapping during idle

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Date:	Wed, 27 May 2009 22:32:28 +0200 (CEST)
From:	Thomas Gleixner <tglx@...utronix.de>
To:	john stultz <johnstul@...ibm.com>
cc:	Jon Hunter <jon-hunter@...com>,
	"linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
	Ingo Molnar <mingo@...e.hu>
Subject: Re: [PATCH 1/2] Dynamic Tick: Prevent clocksource wrapping during
 idle

On Wed, 27 May 2009, john stultz wrote:
> >   Why do you want to recalculate the whole stuff over and over ?
> > 
> >   That computation can be done when the clock source is initialized or
> >   any fundamental change of the clock parameters happens.
> > 
> >   Stick that value into the clocksource struct and just read it out.
> 
> Sigh. 
> 
> I was hoping to avoid hanging another bit of junk off of the clocksource
> struct. 

Sure, but buying that 8 bytes with Einsteinian insanity is nuts.
 
> But I guess we could compute that value on registration and keep it
> around. Changes to mult could effect things, but should be well within
> the 6% safety net we give ourselves.

That was my thought as well, but even if we have to go to 12% it's way
better than doing repeated nonsense on the way to idle.

Thanks,

	tglx
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