tasklet_kill() ensures that we _yield_ the processor until a remote
tasklet is completed. However, this leads to a starvation condition as
being at the bottom of the scheduler's runqueue means that anything else
is able to run, including all hogs keeping the tasklet occupied.
Signed-off-by: Chris Wilson <chris@xxxxxxxxxxxxxxxxxx>
Reviewed-by: Mika Kuoppala <mika.kuoppala@xxxxxxxxxxxxxxx>
---
drivers/gpu/drm/i915/gt/intel_engine.h | 7 ++++++-
drivers/gpu/drm/i915/gt/intel_engine_cs.c | 10 +++++-----
drivers/gpu/drm/i915/i915_request.c | 2 +-
3 files changed, 12 insertions(+), 7 deletions(-)
diff --git a/drivers/gpu/drm/i915/gt/intel_engine.h b/drivers/gpu/drm/i915/gt/intel_engine.h
index 6606b1dbf3d6..47ee8578e511 100644
--- a/drivers/gpu/drm/i915/gt/intel_engine.h
+++ b/drivers/gpu/drm/i915/gt/intel_engine.h
@@ -232,7 +232,12 @@ static inline void __intel_engine_reset(struct intel_engine_cs *engine,
bool intel_engines_are_idle(struct intel_gt *gt);
bool intel_engine_is_idle(struct intel_engine_cs *engine);
-void intel_engine_flush_submission(struct intel_engine_cs *engine);
+
+void __intel_engine_flush_submission(struct intel_engine_cs *engine, bool sync);
+static inline void intel_engine_flush_submission(struct intel_engine_cs *engine)
+{
+ __intel_engine_flush_submission(engine, true);
+}
void intel_engines_reset_default_submission(struct intel_gt *gt);
diff --git a/drivers/gpu/drm/i915/gt/intel_engine_cs.c b/drivers/gpu/drm/i915/gt/intel_engine_cs.c
index 97ceaf7116e8..bb1c1adad78a 100644
--- a/drivers/gpu/drm/i915/gt/intel_engine_cs.c
+++ b/drivers/gpu/drm/i915/gt/intel_engine_cs.c
@@ -1190,17 +1190,13 @@ static bool ring_is_idle(struct intel_engine_cs *engine)
return idle;
}
-void intel_engine_flush_submission(struct intel_engine_cs *engine)
+void __intel_engine_flush_submission(struct intel_engine_cs *engine, bool sync)
{
struct tasklet_struct *t = &engine->execlists.tasklet;
if (!t->func)
return;
- /* Synchronise and wait for the tasklet on another CPU */
- tasklet_kill(t);
-
- /* Having cancelled the tasklet, ensure that is run */
local_bh_disable();
if (tasklet_trylock(t)) {
/* Must wait for any GPU reset in progress. */
@@ -1209,6 +1205,10 @@ void intel_engine_flush_submission(struct intel_engine_cs *engine)
tasklet_unlock(t);
}
local_bh_enable();
+
+ /* Synchronise and wait for the tasklet on another CPU */
+ if (sync)
+ tasklet_unlock_wait(t);
}
/**
diff --git a/drivers/gpu/drm/i915/i915_request.c b/drivers/gpu/drm/i915/i915_request.c
index 2675c6d70779..45744c3ef7c4 100644
--- a/drivers/gpu/drm/i915/i915_request.c
+++ b/drivers/gpu/drm/i915/i915_request.c
@@ -1825,7 +1825,7 @@ long i915_request_wait(struct i915_request *rq,
* for unhappy HW.
*/
if (i915_request_is_ready(rq))
- intel_engine_flush_submission(rq->engine);
+ __intel_engine_flush_submission(rq->engine, false);
for (;;) {
set_current_state(state);
--
2.20.1
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