[PATCH 3/5] drm/i915: During shrink_all we only need to idle the GPU

Chris Wilson
2015-10-01T11:24:49Z

We can forgo an evict-everything here as the shrinker operation itself
will unbind any vma as required. If we explicitly idle the GPU through a
switch to the default context, we not only create a request in an
illegal context (e.g. whilst shrinking during execbuf with a request
already allocated), but switching to the default context will not free
up the memory backing the active contexts - unless in the unlikely
situation that context had already been closed (and just kept arrive by
being the current context). The saving is near zero and the danger real.

To compensate for the loss of the forced retire, add a couple of
retire-requests to i915_gem_shirnk() - this should help free up any
transitive cache from the requests.

Signed-off-by: Chris Wilson <chris@chris-wilson.co.uk>
---
drivers/gpu/drm/i915/i915_gem_shrinker.c | 4 +++-
1 file changed, 3 insertions(+), 1 deletion(-)

diff --git a/drivers/gpu/drm/i915/i915_gem_shrinker.c b/drivers/gpu/drm/i915/i915_gem_shrinker.c
index 88f66a2586ec..2058d162aeb9 100644
--- a/drivers/gpu/drm/i915/i915_gem_shrinker.c
+++ b/drivers/gpu/drm/i915/i915_gem_shrinker.c
@@ -86,6 +86,7 @@ i915_gem_shrink(struct drm_i915_private *dev_priv,
unsigned long count = 0;

trace_i915_gem_shrink(dev_priv, target, flags);
+ i915_gem_retire_requests(dev_priv->dev);

/*
* As we may completely rewrite the (un)bound list whilst unbinding
@@ -141,6 +142,8 @@ i915_gem_shrink(struct drm_i915_private *dev_priv,
list_splice(&still_in_list, phase->list);
}

+ i915_gem_retire_requests(dev_priv->dev);
+
return count;
}

@@ -160,7 +163,6 @@ i915_gem_shrink(struct drm_i915_private *dev_priv,
*/
unsigned long i915_gem_shrink_all(struct drm_i915_private *dev_priv)
{
- i915_gem_evict_everything(dev_priv->dev);
return i915_gem_shrink(dev_priv, -1UL,
I915_SHRINK_BOUND | I915_SHRINK_UNBOUND);
}
--
2.6.0