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Subject: Re: [ANNOUNCE] ktimers subsystem
From: Thomas Gleixner <tglx@linutronix.de>
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To: john stultz <johnstul@us.ibm.com>
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Date: Tue, 20 Sep 2005 00:58:29 +0200
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On Mon, 2005-09-19 at 15:50 -0700, john stultz wrote:
> > 2. All gettimeofday implementations I have looked at do a lot of math
> > anyway, so its definitely more interesting to look at those oddities
> > rather than discussing a single add. John Stulz timeofday rework have a
> > clean solution for this - please do not argue about the div64 in his
> > original patches which he is reworking at the moment.
> 
> The simplest solution is to keep wall-time maintained in a timespec as
> well as the nsec_t based system_time/wall_time_offset combo. This avoids
> the extra add in the hotpath, and only costs an extra add at interrupt
> time.

<NITPICKING>
The crucial question is what's the hot path ? Depending on the
application type I want to avoid the add in the interrupt code. :)
</NITPICKING>


> Many arches have userspace gtod implementations (x86-64, ppc64, and ia64
> as well). Although my timeofday code allows for this as well (I had it
> working for x86-64 awhile back). 

Was not aware of that. Thanks for clarification.

tglx


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