diff options
| -rw-r--r-- | drivers/gpu/drm/i915/intel_ringbuffer.h | 15 |
1 files changed, 14 insertions, 1 deletions
diff --git a/drivers/gpu/drm/i915/intel_ringbuffer.h b/drivers/gpu/drm/i915/intel_ringbuffer.h index 34d0a148e664..1398eb81dee6 100644 --- a/drivers/gpu/drm/i915/intel_ringbuffer.h +++ b/drivers/gpu/drm/i915/intel_ringbuffer.h @@ -592,7 +592,20 @@ intel_engine_has_preemption(const struct intel_engine_cs *engine) static inline bool __execlists_need_preempt(int prio, int last) { - return prio > max(0, last); + /* + * Allow preemption of low -> normal -> high, but we do + * not allow low priority tasks to preempt other low priority + * tasks under the impression that latency for low priority + * tasks does not matter (as much as background throughput), + * so kiss. + * + * More naturally we would write + * prio >= max(0, last); + * except that we wish to prevent triggering preemption at the same + * priority level: the task that is running should remain running + * to preserve FIFO ordering of dependencies. + */ + return prio > max(I915_PRIORITY_NORMAL - 1, last); } static inline void |