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Subject: Re: [RFC][PATCH] linux-2.4.21-pre4_tsc-lost-tick_A0
From: john stultz <johnstul@us.ibm.com>
To: george anzinger <george@mvista.com>
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On Thu, 2003-01-30 at 17:08, george anzinger wrote:
> john stultz wrote:
> > I'm already somewhat cautious that loops_per_jiffy isn't going to cut it
> > with this patch (I'm thinking fast_gettimeoffset_quotient would probably
> > be better). So please let me know if you find any issues with this
> > patch.
> 
> I think you are wondering about the "/", as am I.  Possibly
> a while loop, or, something like
> fast_gettimeoffset_quotient, but scaled to do jiffies
> instead of micro seconds.  Still you SHOULD be doing this so
> seldom that one wonders if the "/" is all that bad.

Yea, I'm assuming it would be rare enough that the div won't be too much
of a performance drop and would make the code more clear. Although if it
is a concern I'm not opposed to speeding it up. 

> Another thing, possibly not so easily fixed given the
> division between "arch" code and common code, but I would
> like to see jiffies updated in only ONE place.  With this
> patch it is updated in .../kernel/timer.c AND in
> .../arch/kernel/time.c.  In the high-res-timers patch I made
> the jiffies update an inline in an "arch" header file so I
> could have the best of both worlds, i.e. update from common
> code using arch resources (TSC, etc).

Yea, I'm not psyched about that as well (not only is it updated twice,
but three times: arch independent, tsc and cyclone). The inline bit
sounds interesting, are you planning on pushing that in?

thanks
-john


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