On Tue, Jun 28, 2016 at 02:55:28PM +0100, Chris Wilson wrote:
> On Tue, Jun 28, 2016 at 02:29:33PM +0100, Tvrtko Ursulin wrote:
> > How would you implement it with cpu_clock? What would you do when
> > re-scheduled?
> 
> unsigned long base;
> int cpu;
> int ret;
> 
> preempt_disable();
> cpu = smp_processor_id();
> base = local_clock() >> 10;
> for (;;) {
>       u64 now = local_clock() >> 10;
>       preempt_enable();
> 
>       if (COND) {
>               ret = 0;
>               break;
>       }
> 
>       if (now - base >= timeout) {
>               ret = -ETIMEOUT;
>               break;
>       }
>       
>       cpu_relax();
> 
>       preempt_disable();
>       if (unlikely(cpu != smp_processor_id()) {
>               timeout -= now - base;

For this, we should scale everything to ns (u64).
-Chris

-- 
Chris Wilson, Intel Open Source Technology Centre
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