[PATCH 02/15] drm/i915: Retire an active batch pool object rather than allocate new

Chris Wilson
2017-02-23T16:18:36Z

Since obj->active_count is only updated upon retirement, if we see an
active object in the batch pool, double check that is still active
before deciding to allocate a new object.

Signed-off-by: Chris Wilson <chris@chris-wilson.co.uk>
---
drivers/gpu/drm/i915/i915_gem_batch_pool.c | 37 ++++++++++++++----------------
1 file changed, 17 insertions(+), 20 deletions(-)

diff --git a/drivers/gpu/drm/i915/i915_gem_batch_pool.c b/drivers/gpu/drm/i915/i915_gem_batch_pool.c
index 99ceae7855f8..41aa598c4f3b 100644
--- a/drivers/gpu/drm/i915/i915_gem_batch_pool.c
+++ b/drivers/gpu/drm/i915/i915_gem_batch_pool.c
@@ -96,8 +96,7 @@ struct drm_i915_gem_object *
i915_gem_batch_pool_get(struct i915_gem_batch_pool *pool,
size_t size)
{
- struct drm_i915_gem_object *obj = NULL;
- struct drm_i915_gem_object *tmp;
+ struct drm_i915_gem_object *obj;
struct list_head *list;
int n, ret;

@@ -112,31 +111,29 @@ i915_gem_batch_pool_get(struct i915_gem_batch_pool *pool,
n = ARRAY_SIZE(pool->cache_list) - 1;
list = &pool->cache_list[n];

- list_for_each_entry(tmp, list, batch_pool_link) {
+ list_for_each_entry(obj, list, batch_pool_link) {
/* The batches are strictly LRU ordered */
- if (i915_gem_object_is_active(tmp))
- break;
+ if (i915_gem_object_is_active(obj)) {
+ if (!reservation_object_test_signaled_rcu(obj->resv,
+ true))
+ break;

- GEM_BUG_ON(!reservation_object_test_signaled_rcu(tmp->resv,
- true));
+ i915_gem_retire_requests(pool->engine->i915);
+ GEM_BUG_ON(i915_gem_object_is_active(obj));
+ }

- if (tmp->base.size >= size) {
- /* Clear the set of shared fences early */
- reservation_object_lock(tmp->resv, NULL);
- reservation_object_add_excl_fence(tmp->resv, NULL);
- reservation_object_unlock(tmp->resv);
+ GEM_BUG_ON(!reservation_object_test_signaled_rcu(obj->resv,
+ true));

- obj = tmp;
- break;
- }
+ if (obj->base.size >= size)
+ goto found;
}

- if (obj == NULL) {
- obj = i915_gem_object_create_internal(pool->engine->i915, size);
- if (IS_ERR(obj))
- return obj;
- }
+ obj = i915_gem_object_create_internal(pool->engine->i915, size);
+ if (IS_ERR(obj))
+ return obj;

+found:
ret = i915_gem_object_pin_pages(obj);
if (ret)
return ERR_PTR(ret);