We need to allocate new BOs in the kernel as part of each frame, but
the CMA allocator is way too slow for that. As an optimization, keep
track of recently-freed BOs and reuse them, with a 1 second timeout to
fully free them back to the system.
This improves 3D performance by about 15%.
Signed-off-by: Eric Anholt <eric at anholt.net>
---
drivers/gpu/drm/vc4/vc4_bo.c | 336 +++++++++++++++++++++++++++++++++++++-
drivers/gpu/drm/vc4/vc4_debugfs.c | 1 +
drivers/gpu/drm/vc4/vc4_drv.c | 6 +-
drivers/gpu/drm/vc4/vc4_drv.h | 49 +++++-
4 files changed, 384 insertions(+), 8 deletions(-)
diff --git a/drivers/gpu/drm/vc4/vc4_bo.c b/drivers/gpu/drm/vc4/vc4_bo.c
index ab9f510..18faa5b 100644
--- a/drivers/gpu/drm/vc4/vc4_bo.c
+++ b/drivers/gpu/drm/vc4/vc4_bo.c
@@ -12,19 +12,229 @@
* access to system memory with no MMU in between. To support it, we
* use the GEM CMA helper functions to allocate contiguous ranges of
* physical memory for our BOs.
+ *
+ * Since the CMA allocator is very slow, we keep a cache of recently
+ * freed BOs around so that the kernel's allocation of objects for 3D
+ * rendering can return quickly.
*/
#include "vc4_drv.h"
-struct vc4_bo *vc4_bo_create(struct drm_device *dev, size_t size)
+static void vc4_bo_stats_dump(struct vc4_dev *vc4)
+{
+ DRM_INFO("num bos allocated: %d\n",
+ vc4->bo_stats.num_allocated);
+ DRM_INFO("size bos allocated: %dkb\n",
+ vc4->bo_stats.size_allocated / 1024);
+ DRM_INFO("num bos used: %d\n",
+ vc4->bo_stats.num_allocated - vc4->bo_stats.num_cached);
+ DRM_INFO("size bos used: %dkb\n",
+ (vc4->bo_stats.size_allocated -
+ vc4->bo_stats.size_cached) / 1024);
+ DRM_INFO("num bos cached: %d\n",
+ vc4->bo_stats.num_cached);
+ DRM_INFO("size bos cached: %dkb\n",
+ vc4->bo_stats.size_cached / 1024);
+}
+
+#ifdef CONFIG_DEBUG_FS
+int vc4_bo_stats_debugfs(struct seq_file *m, void *unused)
+{
+ struct drm_info_node *node = (struct drm_info_node *)m->private;
+ struct drm_device *dev = node->minor->dev;
+ struct vc4_dev *vc4 = to_vc4_dev(dev);
+ struct vc4_bo_stats stats;
+
+ /* Take a snapshot of the current stats with the lock held. */
+ mutex_lock(&vc4->bo_lock);
+ stats = vc4->bo_stats;
+ mutex_unlock(&vc4->bo_lock);
+
+ seq_printf(m, "num bos allocated: %d\n",
+ stats.num_allocated);
+ seq_printf(m, "size bos allocated: %dkb\n",
+ stats.size_allocated / 1024);
+ seq_printf(m, "num bos used: %d\n",
+ stats.num_allocated - stats.num_cached);
+ seq_printf(m, "size bos used: %dkb\n",
+ (stats.size_allocated - stats.size_cached) / 1024);
+ seq_printf(m, "num bos cached: %d\n",
+ stats.num_cached);
+ seq_printf(m, "size bos cached: %dkb\n",
+ stats.size_cached / 1024);
+
+ return 0;
+}
+#endif
+
+static uint32_t bo_page_index(size_t size)
+{
+ return (size / PAGE_SIZE) - 1;
+}
+
+/* Must be called with bo_lock held. */
+static void vc4_bo_destroy(struct vc4_bo *bo)
{
+ struct drm_gem_object *obj = &bo->base.base;
+ struct vc4_dev *vc4 = to_vc4_dev(obj->dev);
+
+ vc4->bo_stats.num_allocated--;
+ vc4->bo_stats.size_allocated -= obj->size;
+ drm_gem_cma_free_object(obj);
+}
+
+/* Must be called with bo_lock held. */
+static void vc4_bo_remove_from_cache(struct vc4_bo *bo)
+{
+ struct drm_gem_object *obj = &bo->base.base;
+ struct vc4_dev *vc4 = to_vc4_dev(obj->dev);
+
+ vc4->bo_stats.num_cached--;
+ vc4->bo_stats.size_cached -= obj->size;
+
+ list_del(&bo->unref_head);
+ list_del(&bo->size_head);
+}
+
+static struct list_head *vc4_get_cache_list_for_size(struct drm_device *dev,
+ size_t size)
+{
+ struct vc4_dev *vc4 = to_vc4_dev(dev);
+ uint32_t page_index = bo_page_index(size);
+
+ if (vc4->bo_cache.size_list_size <= page_index) {
+ uint32_t new_size = max(vc4->bo_cache.size_list_size * 2,
+ page_index + 1);
+ struct list_head *new_list;
+ uint32_t i;
+
+ new_list = kmalloc_array(new_size, sizeof(struct list_head),
+ GFP_KERNEL);
+ if (!new_list)
+ return NULL;
+
+ /* Rebase the old cached BO lists to their new list
+ * head locations.
+ */
+ for (i = 0; i < vc4->bo_cache.size_list_size; i++) {
+ struct list_head *old_list =
+ &vc4->bo_cache.size_list[i];
+
+ if (list_empty(old_list))
+ INIT_LIST_HEAD(&new_list[i]);
+ else
+ list_replace(old_list, &new_list[i]);
+ }
+ /* And initialize the brand new BO list heads. */
+ for (i = vc4->bo_cache.size_list_size; i < new_size; i++)
+ INIT_LIST_HEAD(&new_list[i]);
+
+ kfree(vc4->bo_cache.size_list);
+ vc4->bo_cache.size_list = new_list;
+ vc4->bo_cache.size_list_size = new_size;
+ }
+
+ return &vc4->bo_cache.size_list[page_index];
+}
+
+void vc4_bo_cache_purge(struct drm_device *dev)
+{
+ struct vc4_dev *vc4 = to_vc4_dev(dev);
+
+ mutex_lock(&vc4->bo_lock);
+ while (!list_empty(&vc4->bo_cache.time_list)) {
+ struct vc4_bo *bo = list_last_entry(&vc4->bo_cache.time_list,
+ struct vc4_bo, unref_head);
+ vc4_bo_remove_from_cache(bo);
+ vc4_bo_destroy(bo);
+ }
+ mutex_unlock(&vc4->bo_lock);
+}
+
+static struct vc4_bo *vc4_bo_get_from_cache(struct drm_device *dev,
+ uint32_t size)
+{
+ struct vc4_dev *vc4 = to_vc4_dev(dev);
+ uint32_t page_index = bo_page_index(size);
+ struct vc4_bo *bo = NULL;
+
+ size = roundup(size, PAGE_SIZE);
+
+ mutex_lock(&vc4->bo_lock);
+ if (page_index >= vc4->bo_cache.size_list_size)
+ goto out;
+
+ if (list_empty(&vc4->bo_cache.size_list[page_index]))
+ goto out;
+
+ bo = list_first_entry(&vc4->bo_cache.size_list[page_index],
+ struct vc4_bo, size_head);
+ vc4_bo_remove_from_cache(bo);
+ kref_init(&bo->base.base.refcount);
+
+out:
+ mutex_unlock(&vc4->bo_lock);
+ return bo;
+}
+
+/**
+ * vc4_gem_create_object - Implementation of driver->gem_create_object.
+ *
+ * This lets the CMA helpers allocate object structs for us, and keep
+ * our BO stats correct.
+ */
+struct drm_gem_object *vc4_create_object(struct drm_device *dev, size_t size)
+{
+ struct vc4_dev *vc4 = to_vc4_dev(dev);
+ struct vc4_bo *bo;
+
+ bo = kzalloc(sizeof(*bo), GFP_KERNEL);
+ if (!bo)
+ return ERR_PTR(-ENOMEM);
+
+ mutex_lock(&vc4->bo_lock);
+ vc4->bo_stats.num_allocated++;
+ vc4->bo_stats.size_allocated += size;
+ mutex_unlock(&vc4->bo_lock);
+
+ return &bo->base.base;
+}
+
+struct vc4_bo *vc4_bo_create(struct drm_device *dev, size_t unaligned_size,
+ bool from_cache)
+{
+ size_t size = roundup(unaligned_size, PAGE_SIZE);
+ struct vc4_dev *vc4 = to_vc4_dev(dev);
struct drm_gem_cma_object *cma_obj;
- cma_obj = drm_gem_cma_create(dev, size);
- if (IS_ERR(cma_obj))
+ if (size == 0)
return NULL;
- else
- return to_vc4_bo(&cma_obj->base);
+
+ /* First, try to get a vc4_bo from the kernel BO cache. */
+ if (from_cache) {
+ struct vc4_bo *bo = vc4_bo_get_from_cache(dev, size);
+
+ if (bo)
+ return bo;
+ }
+
+ cma_obj = drm_gem_cma_create(dev, size);
+ if (IS_ERR(cma_obj)) {
+ /*
+ * If we've run out of CMA memory, kill the cache of
+ * CMA allocations we've got laying around and try again.
+ */
+ vc4_bo_cache_purge(dev);
+
+ cma_obj = drm_gem_cma_create(dev, size);
+ if (IS_ERR(cma_obj)) {
+ DRM_ERROR("Failed to allocate from CMA:\n");
+ vc4_bo_stats_dump(vc4);
+ return NULL;
+ }
+ }
+
+ return to_vc4_bo(&cma_obj->base);
}
int vc4_dumb_create(struct drm_file *file_priv,
@@ -41,7 +251,7 @@ int vc4_dumb_create(struct drm_file *file_priv,
if (args->size < args->pitch * args->height)
args->size = args->pitch * args->height;
- bo = vc4_bo_create(dev, roundup(args->size, PAGE_SIZE));
+ bo = vc4_bo_create(dev, args->size, false);
if (!bo)
return -ENOMEM;
@@ -50,3 +260,117 @@ int vc4_dumb_create(struct drm_file *file_priv,
return ret;
}
+
+/* Must be called with bo_lock held. */
+static void vc4_bo_cache_free_old(struct drm_device *dev)
+{
+ struct vc4_dev *vc4 = to_vc4_dev(dev);
+ unsigned long expire_time = jiffies - msecs_to_jiffies(1000);
+
+ while (!list_empty(&vc4->bo_cache.time_list)) {
+ struct vc4_bo *bo = list_last_entry(&vc4->bo_cache.time_list,
+ struct vc4_bo, unref_head);
+ if (time_before(expire_time, bo->free_time)) {
+ mod_timer(&vc4->bo_cache.time_timer,
+ round_jiffies_up(jiffies +
+ msecs_to_jiffies(1000)));
+ return;
+ }
+
+ vc4_bo_remove_from_cache(bo);
+ vc4_bo_destroy(bo);
+ }
+}
+
+/* Called on the last userspace/kernel unreference of the BO. Returns
+ * it to the BO cache if possible, otherwise frees it.
+ *
+ * Note that this is called with the struct_mutex held.
+ */
+void vc4_free_object(struct drm_gem_object *gem_bo)
+{
+ struct drm_device *dev = gem_bo->dev;
+ struct vc4_dev *vc4 = to_vc4_dev(dev);
+ struct vc4_bo *bo = to_vc4_bo(gem_bo);
+ struct list_head *cache_list;
+
+ mutex_lock(&vc4->bo_lock);
+ /* If the object references someone else's memory, we can't cache it.
+ */
+ if (gem_bo->import_attach) {
+ vc4_bo_destroy(bo);
+ goto out;
+ }
+
+ /* Don't cache if it was publicly named. */
+ if (gem_bo->name) {
+ vc4_bo_destroy(bo);
+ goto out;
+ }
+
+ cache_list = vc4_get_cache_list_for_size(dev, gem_bo->size);
+ if (!cache_list) {
+ vc4_bo_destroy(bo);
+ goto out;
+ }
+
+ bo->free_time = jiffies;
+ list_add(&bo->size_head, cache_list);
+ list_add(&bo->unref_head, &vc4->bo_cache.time_list);
+
+ vc4->bo_stats.num_cached++;
+ vc4->bo_stats.size_cached += gem_bo->size;
+
+ vc4_bo_cache_free_old(dev);
+
+out:
+ mutex_unlock(&vc4->bo_lock);
+}
+
+static void vc4_bo_cache_time_work(struct work_struct *work)
+{
+ struct vc4_dev *vc4 =
+ container_of(work, struct vc4_dev, bo_cache.time_work);
+ struct drm_device *dev = vc4->dev;
+
+ mutex_lock(&vc4->bo_lock);
+ vc4_bo_cache_free_old(dev);
+ mutex_unlock(&vc4->bo_lock);
+}
+
+static void vc4_bo_cache_time_timer(unsigned long data)
+{
+ struct drm_device *dev = (struct drm_device *)data;
+ struct vc4_dev *vc4 = to_vc4_dev(dev);
+
+ schedule_work(&vc4->bo_cache.time_work);
+}
+
+void vc4_bo_cache_init(struct drm_device *dev)
+{
+ struct vc4_dev *vc4 = to_vc4_dev(dev);
+
+ mutex_init(&vc4->bo_lock);
+
+ INIT_LIST_HEAD(&vc4->bo_cache.time_list);
+
+ INIT_WORK(&vc4->bo_cache.time_work, vc4_bo_cache_time_work);
+ setup_timer(&vc4->bo_cache.time_timer,
+ vc4_bo_cache_time_timer,
+ (unsigned long)dev);
+}
+
+void vc4_bo_cache_destroy(struct drm_device *dev)
+{
+ struct vc4_dev *vc4 = to_vc4_dev(dev);
+
+ del_timer(&vc4->bo_cache.time_timer);
+ cancel_work_sync(&vc4->bo_cache.time_work);
+
+ vc4_bo_cache_purge(dev);
+
+ if (vc4->bo_stats.num_allocated) {
+ DRM_ERROR("Destroying BO cache while BOs still allocated:\n");
+ vc4_bo_stats_dump(vc4);
+ }
+}
diff --git a/drivers/gpu/drm/vc4/vc4_debugfs.c
b/drivers/gpu/drm/vc4/vc4_debugfs.c
index 4297b0a5..6bcf96e 100644
--- a/drivers/gpu/drm/vc4/vc4_debugfs.c
+++ b/drivers/gpu/drm/vc4/vc4_debugfs.c
@@ -16,6 +16,7 @@
#include "vc4_regs.h"
static const struct drm_info_list vc4_debugfs_list[] = {
+ {"bo_stats", vc4_bo_stats_debugfs, 0},
{"hdmi_regs", vc4_hdmi_debugfs_regs, 0},
{"hvs_regs", vc4_hvs_debugfs_regs, 0},
{"crtc0_regs", vc4_crtc_debugfs_regs, 0, (void *)(uintptr_t)0},
diff --git a/drivers/gpu/drm/vc4/vc4_drv.c b/drivers/gpu/drm/vc4/vc4_drv.c
index 6e73060..da041fa 100644
--- a/drivers/gpu/drm/vc4/vc4_drv.c
+++ b/drivers/gpu/drm/vc4/vc4_drv.c
@@ -92,7 +92,8 @@ static struct drm_driver vc4_drm_driver = {
.debugfs_cleanup = vc4_debugfs_cleanup,
#endif
- .gem_free_object = drm_gem_cma_free_object,
+ .gem_create_object = vc4_create_object,
+ .gem_free_object = vc4_free_object,
.gem_vm_ops = &drm_gem_cma_vm_ops,
.prime_handle_to_fd = drm_gem_prime_handle_to_fd,
@@ -170,6 +171,8 @@ static int vc4_drm_bind(struct device *dev)
drm_dev_set_unique(drm, dev_name(dev));
+ vc4_bo_cache_init(drm);
+
drm_mode_config_init(drm);
if (ret)
goto unref;
@@ -202,6 +205,7 @@ unbind_all:
component_unbind_all(dev, drm);
unref:
drm_dev_unref(drm);
+ vc4_bo_cache_destroy(drm);
return ret;
}
diff --git a/drivers/gpu/drm/vc4/vc4_drv.h b/drivers/gpu/drm/vc4/vc4_drv.h
index fd8319f..39a1ff5 100644
--- a/drivers/gpu/drm/vc4/vc4_drv.h
+++ b/drivers/gpu/drm/vc4/vc4_drv.h
@@ -17,6 +17,37 @@ struct vc4_dev {
struct vc4_crtc *crtc[3];
struct drm_fbdev_cma *fbdev;
+
+ /* The kernel-space BO cache. Tracks buffers that have been
+ * unreferenced by all other users (refcounts of 0!) but not
+ * yet freed, so we can do cheap allocations.
+ */
+ struct vc4_bo_cache {
+ /* Array of list heads for entries in the BO cache,
+ * based on number of pages, so we can do O(1) lookups
+ * in the cache when allocating.
+ */
+ struct list_head *size_list;
+ uint32_t size_list_size;
+
+ /* List of all BOs in the cache, ordered by age, so we
+ * can do O(1) lookups when trying to free old
+ * buffers.
+ */
+ struct list_head time_list;
+ struct work_struct time_work;
+ struct timer_list time_timer;
+ } bo_cache;
+
+ struct vc4_bo_stats {
+ u32 num_allocated;
+ u32 size_allocated;
+ u32 num_cached;
+ u32 size_cached;
+ } bo_stats;
+
+ /* Protects bo_cache and the BO stats. */
+ struct mutex bo_lock;
};
static inline struct vc4_dev *
@@ -27,6 +58,17 @@ to_vc4_dev(struct drm_device *dev)
struct vc4_bo {
struct drm_gem_cma_object base;
+
+ /* List entry for the BO's position in either
+ * vc4_exec_info->unref_list or vc4_dev->bo_cache.time_list
+ */
+ struct list_head unref_head;
+
+ /* Time in jiffies when the BO was put in vc4->bo_cache. */
+ unsigned long free_time;
+
+ /* List entry for the BO's position in vc4_dev->bo_cache.size_list */
+ struct list_head size_head;
};
static inline struct vc4_bo *
@@ -104,13 +146,18 @@ to_vc4_encoder(struct drm_encoder *encoder)
#define wait_for(COND, MS) _wait_for(COND, MS, 1)
/* vc4_bo.c */
+struct drm_gem_object *vc4_create_object(struct drm_device *dev, size_t size);
void vc4_free_object(struct drm_gem_object *gem_obj);
-struct vc4_bo *vc4_bo_create(struct drm_device *dev, size_t size);
+struct vc4_bo *vc4_bo_create(struct drm_device *dev, size_t size,
+ bool from_cache);
int vc4_dumb_create(struct drm_file *file_priv,
struct drm_device *dev,
struct drm_mode_create_dumb *args);
struct dma_buf *vc4_prime_export(struct drm_device *dev,
struct drm_gem_object *obj, int flags);
+void vc4_bo_cache_init(struct drm_device *dev);
+void vc4_bo_cache_destroy(struct drm_device *dev);
+int vc4_bo_stats_debugfs(struct seq_file *m, void *arg);
/* vc4_crtc.c */
extern struct platform_driver vc4_crtc_driver;
--
2.6.2
