[igt-dev] [PATCH i-g-t] igt/perf_pmu: Flush to idle after hang

[Chris Wilson]

Quoting Tvrtko Ursulin (2018-05-30 11:48:16)
> 
> On 25/05/2018 16:14, Chris Wilson wrote:
> > We may not idle immediately after a hang, and indeed may send a pulse
> > down the pipeline periodically to become idle. Rather than make a flimsy
> > assumption about how long we need to sleep before the system idles,
> > wait for the system to declare itself idle; flushing it to idle in the
> > process!
> > 
> > Signed-off-by: Chris Wilson <chris at chris-wilson.co.uk>
> > Cc: Tvrtko Ursulin <tvrtko.ursulin at linux.intel.com>
> > ---
> >   tests/perf_pmu.c | 11 ++---------
> >   1 file changed, 2 insertions(+), 9 deletions(-)
> > 
> > diff --git a/tests/perf_pmu.c b/tests/perf_pmu.c
> > index 590e6526b..9af192dd8 100644
> > --- a/tests/perf_pmu.c
> > +++ b/tests/perf_pmu.c
> > @@ -281,16 +281,9 @@ single(int gem_fd, const struct intel_execution_engine2 *e, unsigned int flags)
> >   
> >       /* Check for idle after hang. */
> >       if (flags & FLAG_HANG) {
> > -             /* Sleep for a bit for reset unwind to settle. */
> > -             usleep(500e3);
> > -             /*
> > -              * Ensure batch was executing before reset, meaning it must be
> > -              * idle by now. Unless it did not even manage to start before we
> > -              * triggered the reset, in which case the idleness check below
> > -              * might fail. The latter is very unlikely since there are two
> > -              * sleeps during which it had an opportunity to start.
> > -              */
> > +             gem_quiescent_gpu(gem_fd);
> >               igt_assert(!gem_bo_busy(gem_fd, spin->handle));
> > +
> >               val = pmu_read_single(fd);
> >               slept = measured_usleep(batch_duration_ns / 1000);
> >               val = pmu_read_single(fd) - val;
> > 
> 
> Reviewed-by: Tvrtko Ursulin <tvrtko.ursulin at intel.com>

That's a relief. I was fearing you might argue that we need some sort of
check that it does idle in a timely fashion without intervention. Off
the top of my head, we do have some gem_wait/gem_eio checks that should
cover that.
-Chris