Do you have any actual numbers for this?
On August 7, 2019 17:02:22 Rob Clark <robdcl...@gmail.com> wrote:
From: Rob Clark <robdcl...@chromium.org>
I noticed slab_free() showing up at the top of perf results in
gl_driver2, due to "streaming" GPU state objects, which are allocated
and destroyed within a single draw call.
In this case, it is guaranteed that we free on the same child pool,
from the same (only) thread accessing the child pool. So add a faster,
but more restricted version of slab_free() to cut the overhead.
Signed-off-by: Rob Clark <robdcl...@chromium.org>
---
src/util/slab.c | 20 ++++++++++++++++++++
src/util/slab.h | 1 +
2 files changed, 21 insertions(+)
diff --git a/src/util/slab.c b/src/util/slab.c
index 62634034fdc..21076a80238 100644
--- a/src/util/slab.c
+++ b/src/util/slab.c
@@ -276,6 +276,26 @@ void slab_free(struct slab_child_pool *pool, void *ptr)
}
}
+/**
+ * Similar to slab_free(), except that freeing an object in a different pool
+ * from the one it was allocated from is *not* allowed.
+ */
+void slab_free_fast(struct slab_child_pool *pool, void *ptr)
+{
+ struct slab_element_header *elt = ((struct slab_element_header*)ptr - 1);
+
+ CHECK_MAGIC(elt, SLAB_MAGIC_ALLOCATED);
+ SET_MAGIC(elt, SLAB_MAGIC_FREE);
+
+ assert(p_atomic_read(&elt->owner) == (intptr_t)pool);
+
+ /* This is the simple case: The caller guarantees that we can safely
+ * access the free list.
+ */
+ elt->next = pool->free;
+ pool->free = elt;
+}
+
/**
* Allocate an object from the slab. Single-threaded (no mutex).
*/
diff --git a/src/util/slab.h b/src/util/slab.h
index 5a25adaf7f4..9748cd95858 100644
--- a/src/util/slab.h
+++ b/src/util/slab.h
@@ -78,6 +78,7 @@ void slab_create_child(struct slab_child_pool *pool,
void slab_destroy_child(struct slab_child_pool *pool);
void *slab_alloc(struct slab_child_pool *pool);
void slab_free(struct slab_child_pool *pool, void *ptr);
+void slab_free_fast(struct slab_child_pool *pool, void *ptr);
struct slab_mempool {
struct slab_parent_pool parent;
--
2.21.0
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