From 13f8458f9a4522bcb7d1856dd8b329ff5d90f887 Mon Sep 17 00:00:00 2001 From: Chris Wilson Date: Tue, 27 Jun 2017 18:37:31 +0100 Subject: [PATCH] drm/i915: Drop flushing of the object free list/worker from i915_gem_suspend i915_gem_suspend() is called from all of our finalization paths (suspend, hibernate, unload). i915_gem_drain_freed_objects() adds an arbitrary delay as it uses an rcu_barrier() to ensure that there are no more freed objects in flight, and this delay causes a large amount of variability in suspend timings. For S3 suspend, we do not need to free pages as doing so does not impact at all upon the system in its suspended state, unlike S4 hibernation where we do want the hibernation image to be as small as possible. Therefore we can forgo waiting inside i915_gem_suspend(), so long as we ensure that we do cleanup before unload (see i915_gem_load_cleanup()) and prefer to reap our objects prior to hibernation (see i915_gem_freeze()). Removing the rcu_barrier() from i915_gem_suspend() improves S3 latency by about 30ms on Skylake (ymmv). Reported-by: David Weinehall Signed-off-by: Chris Wilson Cc: David Weinehall Link: http://patchwork.freedesktop.org/patch/msgid/20170627173731.11566-1-chris@chris-wilson.co.uk Tested-by: David Weinehall Reviewed-by: David Weinehall --- drivers/gpu/drm/i915/i915_gem.c | 2 -- 1 file changed, 2 deletions(-) diff --git a/drivers/gpu/drm/i915/i915_gem.c b/drivers/gpu/drm/i915/i915_gem.c index 36d838677982..f38c84e485ab 100644 --- a/drivers/gpu/drm/i915/i915_gem.c +++ b/drivers/gpu/drm/i915/i915_gem.c @@ -4597,8 +4597,6 @@ int i915_gem_suspend(struct drm_i915_private *dev_priv) while (flush_delayed_work(&dev_priv->gt.idle_work)) ; - i915_gem_drain_freed_objects(dev_priv); - /* Assert that we sucessfully flushed all the work and * reset the GPU back to its idle, low power state. */ -- 2.20.1