drm/i915: Replace a calloc followed by copying data over it with malloc.

Execbufs involve quite a bit of payload, to the extent that cache misses
show up in the profiles here, and a suspicion that some of those cachelines
may get evicted and then reloaded in the subsequent copy.

This is still abstracted like drm_calloc_large since we want to check for
size overflow, and because we want to choose between kmalloc and vmalloc
on the fly.  cairo's interface for malloc-with-calloc's-args was used as
the model.

Signed-off-by: Eric Anholt <eric@anholt.net>

diff --git a/drivers/gpu/drm/i915/i915_gem.c b/drivers/gpu/drm/i915/i915_gem.c
index 2065b8f7e8751f50b749796888381b3a2aaaa6be..481c0ab888c8fea5dbd50febaca93e3e6d26e78b 100644 (file)
--- a/drivers/gpu/drm/i915/i915_gem.c
+++ b/drivers/gpu/drm/i915/i915_gem.c
@@ -3563,8 +3563,8 @@ i915_gem_execbuffer(struct drm_device *dev, void *data,
                return -EINVAL;
        }
        /* Copy in the exec list from userland */
-       exec_list = drm_calloc_large(sizeof(*exec_list), args->buffer_count);
-       object_list = drm_calloc_large(sizeof(*object_list), args->buffer_count);
+       exec_list = drm_malloc_ab(sizeof(*exec_list), args->buffer_count);
+       object_list = drm_malloc_ab(sizeof(*object_list), args->buffer_count);
        if (exec_list == NULL || object_list == NULL) {
                DRM_ERROR("Failed to allocate exec or object list "
                          "for %d buffers\n",

diff --git a/include/drm/drmP.h b/include/drm/drmP.h
index b0b36838ab11a26b155d983b8b64726aa3362905..1b807d0f6cdb0f8b01abe421ed6a9a066d81714e 100644 (file)
--- a/include/drm/drmP.h
+++ b/include/drm/drmP.h
@@ -1545,14 +1545,27 @@ static __inline__ void drm_core_dropmap(struct drm_local_map *map)
 
 static __inline__ void *drm_calloc_large(size_t nmemb, size_t size)
 {
+       if (size != 0 && nmemb > ULONG_MAX / size)
+               return NULL;
+
        if (size * nmemb <= PAGE_SIZE)
            return kcalloc(nmemb, size, GFP_KERNEL);
 
+       return __vmalloc(size * nmemb,
+                        GFP_KERNEL | __GFP_HIGHMEM | __GFP_ZERO, PAGE_KERNEL);
+}
+
+/* Modeled after cairo's malloc_ab, it's like calloc but without the zeroing. */
+static __inline__ void *drm_malloc_ab(size_t nmemb, size_t size)
+{
        if (size != 0 && nmemb > ULONG_MAX / size)
                return NULL;
 
+       if (size * nmemb <= PAGE_SIZE)
+           return kmalloc(nmemb * size, GFP_KERNEL);
+
        return __vmalloc(size * nmemb,
-                        GFP_KERNEL | __GFP_HIGHMEM | __GFP_ZERO, PAGE_KERNEL);
+                        GFP_KERNEL | __GFP_HIGHMEM, PAGE_KERNEL);
 }
 
 static __inline void drm_free_large(void *ptr)