If we are forced to do an uninterruptible wait for a result from the
GPU, boost the qos of DMA operations to minimise the latency and
minimise the amount of time spent waiting for the operation whilst
uninterruptible.
This shaves a modicum of time off waiting for GPU operations to
complete before performing a MMIO flip, for example.
Signed-off-by: Chris Wilson <chris at chris-wilson.co.uk>
---
drivers/gpu/drm/i915/i915_gem.c | 12 ++++++++++--
1 file changed, 10 insertions(+), 2 deletions(-)
diff --git a/drivers/gpu/drm/i915/i915_gem.c b/drivers/gpu/drm/i915/i915_gem.c
index f532a01..f5da4a0 100644
--- a/drivers/gpu/drm/i915/i915_gem.c
+++ b/drivers/gpu/drm/i915/i915_gem.c
@@ -1013,14 +1013,22 @@ static int __wait_seqno(struct intel_ring_buffer *ring, u32 seqno,
i915_reset_in_progress(&dev_priv->gpu_error) || \
reset_counter != atomic_read(&dev_priv->gpu_error.reset_counter))
do {
- if (interruptible)
+ if (interruptible) {
end = wait_event_interruptible_timeout(ring->irq_queue,
EXIT_COND,
timeout_jiffies);
- else
+ } else {
+ struct pm_qos_request qos;
+
+ memset(&qos, 0, sizeof(qos));
+ pm_qos_add_request(&qos, PM_QOS_CPU_DMA_LATENCY, 0);
+
end = wait_event_timeout(ring->irq_queue, EXIT_COND,
timeout_jiffies);
+ pm_qos_remove_request(&qos);
+ }
+
/* We need to check whether any gpu reset happened in between
* the caller grabbing the seqno and now ... */
if (reset_counter != atomic_read(&dev_priv->gpu_error.reset_counter))
--
1.8.3.2
