[Bug 68716] [SNA][HSW] Dragging windows in Gnome3 overview is less smooth than with UXA

[bugzilla-daemon at freedesktop.org]

https://bugs.freedesktop.org/show_bug.cgi?id=68716

--- Comment #11 from Chris Wilson <chris at chris-wilson.co.uk> ---
Reading the traces, the biggest difference is that in the triple-buffer case,
the GPU is completing operations much faster (about 3x). So this feels like rc6
wakeup latency (when triple buffering the GPU never sleeps, but with double
buffering we have periods of over 10ms idle whilst waiting for the
flip-completion.)

This "fixes" it for me:

diff --git a/drivers/gpu/drm/i915/i915_gem.c b/drivers/gpu/drm/i915/i915_gem.c
index dad0777..80f8730 100644
--- a/drivers/gpu/drm/i915/i915_gem.c
+++ b/drivers/gpu/drm/i915/i915_gem.c
@@ -2704,6 +2704,10 @@ i915_gem_object_sync(struct drm_i915_gem_object *obj,

        ret = 0;
        if (!i915_seqno_passed(from->get_seqno(from, false), seqno)) {
+               struct drm_i915_private *dev_priv = to_i915(obj->base.dev);
+               if (dev_priv->info->gen >= 6)
+                       gen6_rps_boost(dev_priv);
+
                ret = i915_gem_check_olr(from, seqno);
                if (ret)
                        return ret;

can you please test this on top of the for-bug68716 series?

I'm not happy with that approach just yet, it reeks of overkill.

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