Re: [PATCH] time : SMP friendly alignment of struct clocksource

[Daniel Walker]

On Tue, 2007-03-20 at 10:58 -0700, john stultz wrote:

> >  	/* timekeeping specific data, ignore */
> > -	cycle_t cycle_last, cycle_interval;
> > -	u64 xtime_nsec, xtime_interval;
> > +	cycle_t cycle_interval;
> > +	u64	xtime_interval;
> > +	/*
> > +	 * Second part is written at each timer interrupt
> > +	 * Keep it in a different cache line to dirty no
> > +	 * more than one cache line.
> > +	 */
> > +	cycle_t cycle_last ____cacheline_aligned_in_smp;
> > +	u64 xtime_nsec;
> >  	s64 error;

What was the motivation for having these (cycle_last for example) in the
clocksource structure. I recall them being added in there at one point,
but I'm not sure why.. Specifically the ones that are updated often.

Daniel

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