On 13/04/18 08:59, Chris Wilson wrote:
Quoting Antonio Argenziano (2018-04-13 16:54:27)


On 13/04/18 07:14, Chris Wilson wrote:
Set up a unpreemptible spinner such that the only way we can inject a
high priority request onto the GPU is by resetting the spinner. The test
fails if we trigger hangcheck rather than the fast timeout mechanism.

Signed-off-by: Chris Wilson <ch...@chris-wilson.co.uk>
---
   lib/i915/gem_context.c    | 72 +++++++++++++++++++++++++++++++--------
   lib/i915/gem_context.h    |  3 ++
   lib/igt_dummyload.c       | 12 +++++--
   lib/igt_dummyload.h       |  3 ++
   tests/gem_exec_schedule.c | 34 ++++++++++++++++++
   5 files changed, 106 insertions(+), 18 deletions(-)


...

@@ -449,8 +457,6 @@ void igt_spin_batch_end(igt_spin_t *spin)
       if (!spin)
               return;
- igt_assert(*spin->batch == MI_ARB_CHK ||
-                *spin->batch == MI_BATCH_BUFFER_END);

I am not sure why we needed this, but it seems safe to remove.

       *spin->batch = MI_BATCH_BUFFER_END;
       __sync_synchronize();
   }

diff --git a/tests/gem_exec_schedule.c b/tests/gem_exec_schedule.c
index 6ff15b6ef..93254945b 100644
--- a/tests/gem_exec_schedule.c
+++ b/tests/gem_exec_schedule.c
@@ -656,6 +656,37 @@ static void preemptive_hang(int fd, unsigned ring)
       gem_context_destroy(fd, ctx[HI]);
   }
+static void preempt_timeout(int fd, unsigned ring)
+{
+     igt_spin_t *spin[3];
+     uint32_t ctx;
+
+     igt_require(__gem_context_set_preempt_timeout(fd, 0, 0));
+
+     ctx = gem_context_create(fd);
+     gem_context_set_priority(fd, ctx, MIN_PRIO);
+     spin[0] = __igt_spin_batch_new_hang(fd, ctx, ring);
+     spin[1] = __igt_spin_batch_new_hang(fd, ctx, ring);
Should we send MAX_ELSP_QLEN batches to match other preemption tests?

+     gem_context_destroy(fd, ctx);
+
+     ctx = gem_context_create(fd);
+     gem_context_set_priority(fd, ctx, MAX_PRIO);
+     gem_context_set_preempt_timeout(fd, ctx, 1000 * 1000);
+     spin[2] = __igt_spin_batch_new(fd, ctx, ring, 0);
+     gem_context_destroy(fd, ctx);
+
+     igt_spin_batch_end(spin[2]);
+     gem_sync(fd, spin[2]->handle);

Does this guarantee that spin[1] did not overtake spin[2]?

It does as well. Neither spin[0] or spin[1] can complete without being
reset at this point. If they are reset (by hangcheck) we detect that and

Cool.

die. What we expect to happen is spin[0] is (more or less, there is still
dmesg) silently killed by the preempt timeout. If that timeout doesn't

The silent part is interesting, how do we make sure that during normal preemption operations (e.g. preempt on an ARB_CHECK) we didn't silently discard the preempted batch? Do we care?

Test looks good,
Reviewed-by: Antonio Argenziano <antonio.argenzi...@intel.com>

Thanks,
Antonio

happen, more hangcheck. What we don't check here is how quick. Now we
could reasonably assert that the spin[2] -> gem_sync takes less than 2ms.
-Chris

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