Re: [igt-dev] [PATCH i-g-t] i915/gem_exec_schedule: Check deps along implicit inter-engine semaphores

Daniele Ceraolo Spurio
2019-04-24T17:53:08Z

On 4/24/19 8:47 AM, Chris Wilson wrote:
> Given an implicit semaphore from one engine to the next, check that if
> we skip the wait on that semaphore the following batch although
> submitted early (as it depends along the single engine timeline) is not
> executed ahead of its dependency.
>
> Signed-off-by: Chris Wilson <chris@chris-wilson.co.uk>
> Cc: Daniele Ceraolo Spurio <daniele.ceraolospurio@intel.com>
> Cc: Matthew Brost <matthew.brost@intel.com>

Reviewed-by: Daniele Ceraolo Spurio <daniele.ceraolospurio@intel.com>

some nitpicks below.

> ---
> Make sure there is actually a semaphore (read-read doesn't generate an
> interengine dependency!)
> ---
> tests/i915/gem_exec_schedule.c | 75 ++++++++++++++++++++++++++++++++++
> 1 file changed, 75 insertions(+)
>
> diff --git a/tests/i915/gem_exec_schedule.c b/tests/i915/gem_exec_schedule.c
> index 3590b739a..a6b74b3b6 100644
> --- a/tests/i915/gem_exec_schedule.c
> +++ b/tests/i915/gem_exec_schedule.c
> @@ -603,6 +603,79 @@ static void semaphore_resolve(int i915)
> gem_context_destroy(i915, outer);
> }
>
> +static void semaphore_noskip(int i915)
> +{
> + unsigned int engine, other;
> + uint32_t ctx;
> +
> + igt_assert(intel_get_drm_devid(i915) >= 8);

I would move this to igt_require since the subtest_group only requires
scheduler & priority and even if we currently don't enable those
pre-gen8 I don't think we can assume we never will.

> +
> + ctx = gem_context_create(i915);
> +
> + for_each_physical_engine(i915, engine) {
> + for_each_physical_engine(i915, other) {

Is it worth hiding the double loop in its own macro? e.g.:

for_each_physical_engine_pair(i915, engine1, engine2)

> + struct drm_i915_gem_exec_object2 obj[3];
> + struct drm_i915_gem_execbuffer2 eb;
> + igt_spin_t *chain, *spin;
> + uint32_t handle, cancel;
> + uint32_t *cs, *map;
> +
> + if (other == engine || !gem_can_store_dword(i915, other))
> + continue;
> +
> + chain = __igt_spin_new(i915, .engine = engine);
> +
> + spin = __igt_spin_new(i915, .engine = other);
> + igt_spin_end(spin); /* we just want its address for later */
> + gem_sync(i915, spin->handle);
> + igt_spin_reset(spin);
> +
> + handle = gem_create(i915, 4096);
> + cs = map = gem_mmap__cpu(i915, handle, 0, 4096, PROT_WRITE);
> +
> + /* Cancel the following spinner */
> + *cs++ = MI_STORE_DWORD_IMM;
> + *cs++ = spin->obj[1].offset + offset_in_page(spin->condition);
> + *cs++ = 0;
> + *cs++ = MI_BATCH_BUFFER_END;
> +
> + *cs++ = MI_BATCH_BUFFER_END;
> + munmap(map, 4096);
> +
> + memset(obj, 0, sizeof(obj));
> + obj[0] = chain->obj[1];
> + obj[0].flags |= EXEC_OBJECT_WRITE;
> + obj[1] = spin->obj[1];
> + obj[2].handle = handle;
> + memset(&eb, 0, sizeof(eb));
> + eb.buffer_count = 3;
> + eb.buffers_ptr = to_user_pointer(obj);
> + eb.rsvd1 = ctx;
> + eb.flags = other;
> + gem_execbuf(i915, &eb);
> +
> + memset(obj, 0, sizeof(obj));
> + obj[0].handle = handle;
> + obj[0].flags = EXEC_OBJECT_WRITE;
> + obj[1] = spin->obj[1];
> + memset(&eb, 0, sizeof(eb));
> + eb.buffer_count = 2;
> + eb.buffers_ptr = to_user_pointer(obj);
> + eb.flags = other;
> + gem_execbuf(i915, &eb);
> +
> + igt_spin_set_timeout(chain, NSEC_PER_SEC / 100);
> + gem_sync(i915, spin->handle); /* To hang unless cancel runs! */
> +
> + gem_close(i915, handle);
> + igt_spin_free(i915, spin);
> + igt_spin_free(i915, chain);
> + }
> + }
> +
> + gem_context_destroy(i915, ctx);
> +}
> +
> static void reorder(int fd, unsigned ring, unsigned flags)
> #define EQUAL 1
> {
> @@ -1592,6 +1665,8 @@ igt_main
> semaphore_codependency(fd);
> igt_subtest("semaphore-resolve")
> semaphore_resolve(fd);

semaphore_resolve isn't merged yet ;)

Daniele

> + igt_subtest("semaphore-noskip")
> + semaphore_noskip(fd);
>
> igt_subtest("smoketest-all")
> smoketest(fd, ALL_ENGINES, 30);
>