On Thu, Feb 16, 2017 at 02:22:52PM +0000, Chris Wilson wrote:
> When the timer expires for checking on interrupt processing, check to
> see if any interrupts arrived within the last time period. If real
> interrupts are still being delivered, we can be reassured that we
> haven't missed the final interrupt as the waiter will still be woken.
> Only once all activity ceases, do we have to worry about the waiter
> never being woken and so need to install a timer to kick the waiter for
> a slow arrival of a seqno.
>
> Signed-off-by: Chris Wilson <chris@xxxxxxxxxxxxxxxxxx>
> Cc: Tvrtko Ursulin <tvrtko.ursulin@xxxxxxxxx>
> Reviewed-by: Tvrtko Ursulin <tvrtko.ursulin@xxxxxxxxx>
> ---
> @@ -34,8 +39,9 @@ static void intel_breadcrumbs_hangcheck(unsigned long data)
> if (!b->irq_enabled)
> return;
>
> - if (time_before(jiffies, b->timeout)) {
> - mod_timer(&b->hangcheck, b->timeout);
> + if (b->hangcheck_interrupts != atomic_read(&engine->irq_count)) {
> + b->hangcheck_interrupts = atomic_read(&engine->irq_count);
> + mod_timer(&b->hangcheck, wait_timeout());
> return;
Still toying with the idea of how to check for a delayed waiter - we
don't want to blame the hw if the waiter hasn't yet been run (perhaps
due to low priority on a loaded system).
Tempted to grab the b->first_wait and do a check against tsk->state.
Of course that may well be overkill!
-Chris
--
Chris Wilson, Intel Open Source Technology Centre
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