On Thu, Feb 11, 2016 at 06:03:10PM +0000, Tvrtko Ursulin wrote:
> From: Tvrtko Ursulin <tvrtko.ursulin@xxxxxxxxx>
>
> Assorted changes most likely without any practical effect
> apart from a tiny reduction in generated code for the interrupt
> handler and request submission.
>
> * Remove needless initialization.
> * Improve cache locality by reorganizing code and/or using
> branch hints to keep unexpected or error conditions out
> of line.
> * Favor busy submit path vs. empty queue.
> * Less branching in hot-paths.
Sadly there are panics here to be taken care of before optimisations. :|
> Signed-off-by: Tvrtko Ursulin <tvrtko.ursulin@xxxxxxxxx>
> ---
> drivers/gpu/drm/i915/intel_lrc.c | 91 ++++++++++++++++-----------------
> drivers/gpu/drm/i915/intel_ringbuffer.h | 1 +
> 2 files changed, 44 insertions(+), 48 deletions(-)
>
> diff --git a/drivers/gpu/drm/i915/intel_lrc.c b/drivers/gpu/drm/i915/intel_lrc.c
> index 951f1e6af947..589d6404b5ca 100644
> --- a/drivers/gpu/drm/i915/intel_lrc.c
> +++ b/drivers/gpu/drm/i915/intel_lrc.c
> @@ -269,6 +269,9 @@ logical_ring_init_platform_invariants(struct intel_engine_cs *ring)
> {
> struct drm_device *dev = ring->dev;
>
> + if (IS_GEN8(dev) || IS_GEN9(dev))
> + ring->idle_lite_restore_wa = ~0;
> +
> ring->disable_lite_restore_wa = (IS_SKL_REVID(dev, 0, SKL_REVID_B0) ||
> IS_BXT_REVID(dev, 0, BXT_REVID_A1)) &&
> (ring->id == VCS || ring->id == VCS2);
> @@ -424,7 +427,7 @@ static void execlists_submit_requests(struct drm_i915_gem_request *rq0,
> static void execlists_context_unqueue(struct intel_engine_cs *ring)
> {
> struct drm_i915_gem_request *req0 = NULL, *req1 = NULL;
> - struct drm_i915_gem_request *cursor = NULL, *tmp = NULL;
> + struct drm_i915_gem_request *cursor, *tmp;
>
> assert_spin_locked(&ring->execlist_lock);
>
> @@ -434,9 +437,6 @@ static void execlists_context_unqueue(struct intel_engine_cs *ring)
> */
> WARN_ON(!intel_irqs_enabled(ring->dev->dev_private));
>
> - if (list_empty(&ring->execlist_queue))
> - return;
> -
> /* Try to read in pairs */
> list_for_each_entry_safe(cursor, tmp, &ring->execlist_queue,
> execlist_link) {
> @@ -451,37 +451,35 @@ static void execlists_context_unqueue(struct intel_engine_cs *ring)
> req0 = cursor;
> } else {
> req1 = cursor;
> + WARN_ON(req1->elsp_submitted);
> break;
> }
> }
>
> - if (IS_GEN8(ring->dev) || IS_GEN9(ring->dev)) {
> + if (unlikely(!req0))
> + return;
> +
> + if (req0->elsp_submitted & ring->idle_lite_restore_wa) {
If you are going for the microptimsation, just do
if (req->elsp_submitted)
We unconditionally prepare the ringbuffer for the wa and currently apply
it everywhere (and future hw will not be taking this path, aiui at least).
-Chris
--
Chris Wilson, Intel Open Source Technology Centre
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