On 06/07/2017 12:44, Chris Wilson wrote:
Quoting Tvrtko Ursulin (2017-07-06 12:40:56)
On 05/07/2017 18:21, Chris Wilson wrote:
Inspired by Tvrtko's critique of the reaping of the stale contexts
before allocating a new one, also limit the freed object reaping to the
oldest stale object before allocating a fresh object. Unlike contexts,
objects may have radically different sizes of backing storage, but
similar to contexts, whilst we want to prevent starvation due to
excessive freed lists, we also want do not want to delay fresh
allocations for too long. Only freeing the oldest on the freed object
list before each allocation is a reasonable compromise.
Signed-off-by: Chris Wilson <chris@xxxxxxxxxxxxxxxxxx>
Cc: Tvrtko Ursulin <tvrtko.ursulin@xxxxxxxxx>
---
drivers/gpu/drm/i915/i915_gem.c | 8 ++++++--
1 file changed, 6 insertions(+), 2 deletions(-)
diff --git a/drivers/gpu/drm/i915/i915_gem.c b/drivers/gpu/drm/i915/i915_gem.c
index 91145c39cd43..2048532c9cae 100644
--- a/drivers/gpu/drm/i915/i915_gem.c
+++ b/drivers/gpu/drm/i915/i915_gem.c
@@ -4473,9 +4473,13 @@ static void i915_gem_flush_free_objects(struct drm_i915_private *i915)
{
struct llist_node *freed;
- freed = llist_del_all(&i915->mm.free_list);
- if (unlikely(freed))
+ freed = NULL;
+ if (!llist_empty(&i915->mm.free_list))
+ freed = llist_del_first(&i915->mm.free_list);
Looks like llist_del_first already handles the empty list case by
returning NULL so you could simplify this.
I didn't want the extra call here (since object allocation is far more
frequent than context allocation), but that's just me.
Ah OK then, I didn't spot that angle. R-b applies to v1 then. Could be
useful to stick a comment in there so someone does not clean it up in
the future. :)
Regards,
Tvrtko
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