On Thu, 20 Oct 2005, Steven Rostedt wrote:
>
> On Thu, 20 Oct 2005, Ingo Molnar wrote:
>
> >
> > * Steven Rostedt <[email protected]> wrote:
> >
> > > static inline nsec_t __get_nsec_offset(void)
> > > {
> > > cycle_t cycle_now, cycle_delta;
> > > nsec_t ns_offset;
> > >
> > > /* read clocksource */
> > > cycle_now = read_clocksource(clock);
> > >
> > > /* calculate the delta since the last timeofday_periodic_hook */
> > > cycle_delta = (cycle_now - cycle_last) & clock->mask;
> > >
> > > /* convert to nanoseconds */
> > > ns_offset = cyc2ns(clock, ntp_adj, cycle_delta);
> > >
> > > /* Special case for jiffies tick/offset based systems
> > > * add arch specific offset
> > > */
> > > ns_offset += arch_getoffset();
> > >
> > > return ns_offset;
> > > }
> > >
> > > cycle_now is 32 bits. If the clocksource overflows (which it can in
> > > 30 seconds) the cyclec_delta will be wrong.
> >
> > isnt cycle_t 64 bits?
> >
>
> Not anymore.
>
> include/linux/time.h:
>
> /* timeofday base types */
> typedef s64 nsec_t;
> typedef unsigned long cycle_t;
>
FYI,
I just switched cycle_t to u64 and hackbench no longer makes the time go
backwards.
John, would this cause any problems to keep cycle_t at s64?
-- Steve
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