On 19/02/2018 19:21, Chris Wilson wrote:
Quoting Tvrtko Ursulin (2018-02-19 19:12:51)
From: Tvrtko Ursulin <tvrtko.ursu...@intel.com>

Verify that the reported busyness is in line with what would we expect
from a batch which causes a hang and gets kicked out from the engine.

Signed-off-by: Tvrtko Ursulin <tvrtko.ursu...@intel.com>
---
  tests/perf_pmu.c | 41 +++++++++++++++++++++++++++++++++++------
  1 file changed, 35 insertions(+), 6 deletions(-)

diff --git a/tests/perf_pmu.c b/tests/perf_pmu.c
index 7fab73e22c2d..90b6ec4db32d 100644
--- a/tests/perf_pmu.c
+++ b/tests/perf_pmu.c
@@ -168,6 +168,7 @@ static unsigned int e2ring(int gem_fd, const struct 
intel_execution_engine2 *e)
  #define TEST_TRAILING_IDLE (4)
  #define TEST_RUNTIME_PM (8)
  #define FLAG_LONG (16)
+#define FLAG_HANG (32)
static void end_spin(int fd, igt_spin_t *spin, unsigned int flags)
  {
@@ -186,11 +187,15 @@ static void end_spin(int fd, igt_spin_t *spin, unsigned 
int flags)
  static void
  single(int gem_fd, const struct intel_execution_engine2 *e, unsigned int 
flags)
  {
+       const unsigned int hang_us = 10e6;
         unsigned long slept;
         igt_spin_t *spin;
-       uint64_t val;
+       uint64_t val[2], ts[2];
         int fd;
+ if (flags & FLAG_HANG)
+               gem_quiescent_gpu(gem_fd);
+
         fd = open_pmu(I915_PMU_ENGINE_BUSY(e->class, e->instance));
if (flags & TEST_BUSY)
@@ -198,17 +203,36 @@ single(int gem_fd, const struct intel_execution_engine2 
*e, unsigned int flags)
         else
                 spin = NULL;
- val = pmu_read_single(fd);
-       slept = measured_usleep(batch_duration_ns / 1000);
+       val[0] = __pmu_read_single(fd, &ts[0]);
+       slept = measured_usleep(flags & FLAG_HANG ?
+                               hang_us : batch_duration_ns / 1000);
         if (flags & TEST_TRAILING_IDLE)
                 end_spin(gem_fd, spin, flags);
-       val = pmu_read_single(fd) - val;
+       val[1] = pmu_read_single(fd);
end_spin(gem_fd, spin, FLAG_SYNC);
         igt_spin_batch_free(gem_fd, spin);
-       close(fd);
- assert_within_epsilon(val, flags & TEST_BUSY ? slept : 0.f, tolerance);
+       if ((flags & TEST_BUSY) && (flags & FLAG_HANG)) {
+               val[1] = __pmu_read_single(fd, &ts[1]);
+               close(fd);
+               igt_info("sampled with hang %.3fms / %.3fms\n",
+                        (val[1] - val[0]) / 1e6, (ts[1] - ts[0]) / 1e6);
+               /* Check that some busyness was reported. */
+               igt_assert(val[1] - val[0] > 0);
+               /*
+                * But not more than some reasonable value before which we
+                * expected the spinner to be kicked out.
+                */

So 120s? And even that carries internal knowledge from across the ages.

I don't think this is a sensible test. What would be reasonable is
something like

        spinner()
        val[0] = pmu()
        sleep()
        igt_force_gpu_reset()
        val[1] = pmu();
        d_busy = val[1] - val[0]
        sleep()
        val[2] = pmu()
        d_idle = val[2] - val[1];

Then d_busy should be d_ts, and d_idle should be 0. i.e. the
igt_force_gpu_reset() is just an indirect igt_spin_batch_end().

Yeah I am not claiming the test is great. I threw it together quickly when I suspected something is going bad. Just want to get some results overnight so I can despair tomorrow.

Regards,

Tvrtko
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