On 27/05/2021 11:22, Tvrtko Ursulin wrote:
On 27/05/2021 11:13, Daniel Vetter wrote:
On Wed, May 26, 2021 at 11:20:13AM +0100, Tvrtko Ursulin wrote:
On 25/05/2021 15:47, Daniel Vetter wrote:
On Tue, May 25, 2021 at 03:19:47PM +0100, Tvrtko Ursulin wrote:
+ dri-devel as per process
On 25/05/2021 14:55, Tejas Upadhyay wrote:
v2: Only declare timeslicing if we can safely preempt userspace.
Commit message got butchered up somehow so you'll need to fix that
at some
point.
Regards,
Tvrtko
Fixes: 8ee36e048c98 ("drm/i915/execlists: Minimalistic timeslicing")
Signed-off-by: Chris Wilson <chris@xxxxxxxxxxxxxxxxxx>
Cc: Tvrtko Ursulin <tvrtko.ursulin@xxxxxxxxx>
Reviewed-by: Tvrtko Ursulin <tvrtko.ursulin@xxxxxxxxx>
---
drivers/gpu/drm/i915/gt/intel_engine_user.c | 1 +
include/uapi/drm/i915_drm.h | 1 +
2 files changed, 2 insertions(+)
diff --git a/drivers/gpu/drm/i915/gt/intel_engine_user.c
b/drivers/gpu/drm/i915/gt/intel_engine_user.c
index 3cca7ea2d6ea..12d165566ed2 100644
--- a/drivers/gpu/drm/i915/gt/intel_engine_user.c
+++ b/drivers/gpu/drm/i915/gt/intel_engine_user.c
@@ -98,6 +98,7 @@ static void set_scheduler_caps(struct
drm_i915_private *i915)
MAP(HAS_PREEMPTION, PREEMPTION),
MAP(HAS_SEMAPHORES, SEMAPHORES),
MAP(SUPPORTS_STATS, ENGINE_BUSY_STATS),
+ MAP(TIMESLICE_BIT, TIMESLICING),
#undef MAP
};
struct intel_engine_cs *engine;
diff --git a/include/uapi/drm/i915_drm.h
b/include/uapi/drm/i915_drm.h
index c2c7759b7d2e..af2212d6113c 100644
--- a/include/uapi/drm/i915_drm.h
+++ b/include/uapi/drm/i915_drm.h
@@ -572,6 +572,7 @@ typedef struct drm_i915_irq_wait {
#define I915_SCHEDULER_CAP_PREEMPTION (1ul << 2)
#define I915_SCHEDULER_CAP_SEMAPHORES (1ul << 3)
#define I915_SCHEDULER_CAP_ENGINE_BUSY_STATS (1ul << 4)
+#define I915_SCHEDULER_CAP_TIMESLICING (1ul << 5)
Since this is uapi I think we should at least have some nice kerneldoc
that explains what exactly this is, what for (link to userspace) and
all
that. Ideally also minimally filing in the gaps in our uapi docs for
stuff
this references.
IIUC there is no userspace apart from IGT needing it not to fail
scheduling
tests on ADL.
Current tests use "has preemption + has semaphores" as a proxy to
answer the
"does the kernel support timeslicing" question. This stops working
with the
Guc backend because GuC decided not to support semaphores (for
reasons yet
unknown, see other thread), so explicit "has timeslicing" flag is
needed in
order for tests to know that GuC is supposed to support timeslicing,
even if
it doesn't use semaphores for inter-ring synchronisation.
Since this if for igt only: Cant we do just extend the check in igt with
an || GEN >= 12? I really hope that our future hw will continue to
support
timeslicing ...
Not the gen 12 check, but possible I think. Explicit feature test would
be better, but if definitely not allowed then along the lines of:
has_timeslicing =
(has_preemption && has_semaphores) || uses_guc_submission;
One catch is that timeslicing in GuC will be disabled both if at compile
time CONFIG_DRM_I915_TIMESLICE_DURATION is set to zero, or if at runtime
engine->props.timeslice_duration_ms is equally set to zero.
So I think what is needed on top of the above check is to walk all
engines in sysfs and check that timeslicing hasn't explicitly been
disabled for any one of them.
If we are talking about the global flag at least. Per engine tests could
do better I guess, but I don't think that complication is worth the effort.
Regards,
Tvrtko
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