Re: [PATCH] Use of TSC with SMP and different CPU's

From: Boris Okun (bokun@home.com)
Date: Thu Mar 09 2000 - 12:59:42 EST


Andrea Arcangeli wrote:
 
> For doing that you should run some code also on the other CPU. Why do you
> want to do that? It's slower. Storing 64bit information is much faster.
>

But I am going to do that only at interrupt time, instead of 64bit
arithmetic in do_gettimeofday(). Also in this way I don't have to store
current time.

I also think that the right place to store rdtsc is when we update xtime
(is it update_wallclock ?)
that way delay_at_interrupt is not needed and we have less discrepancy
between
xtime and gettimeofday()

> btw, the per-cpu fields you added should really be cacheline aligned or
> you'll have cacheline pingpong each time the timer irq happens on another
> CPU.

Which one should I use ____cacheline_aligned or __cacheline_aligned ?

Boris

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