drm/i915/execbuffer: Reorder binding of objects to favour restrictions

As the mappable portion of the aperture is always a small subset at the
start of the GTT, it is allocated preferentially by drm_mm. This is
useful in case we ever need to map an object later. However, if you have
a large object that can consume the entire mappable region of the
GTT this prevents the batchbuffer from fitting and so causing an error.
Instead allocate all those that require a mapping up front in order to
improve the likelihood of finding sufficient space to bind them.

Signed-off-by: Chris Wilson <chris@chris-wilson.co.uk>

2 files changed, 47 insertions, 26 deletions

diff --git a/drivers/gpu/drm/i915/i915_drv.h b/drivers/gpu/drm/i915/i915_drv.h
index 6130f77c26bf..385fc7ec39d3 100644
--- a/drivers/gpu/drm/i915/i915_drv.h
+++ b/drivers/gpu/drm/i915/i915_drv.h
@@ -796,6 +796,7 @@ struct drm_i915_gem_object {
          */
         struct hlist_node exec_node;
         unsigned long exec_handle;
+        struct drm_i915_gem_exec_object2 *exec_entry;
 
         /**
          * Current offset of the object in GTT space.
diff --git a/drivers/gpu/drm/i915/i915_gem_execbuffer.c b/drivers/gpu/drm/i915/i915_gem_execbuffer.c
index 0445770cc23c..e69834341ef0 100644
--- a/drivers/gpu/drm/i915/i915_gem_execbuffer.c
+++ b/drivers/gpu/drm/i915/i915_gem_execbuffer.c
@@ -268,7 +268,6 @@ eb_destroy(struct eb_objects *eb)
 static int
 i915_gem_execbuffer_relocate_entry(struct drm_i915_gem_object *obj,
                                    struct eb_objects *eb,
-                                   struct drm_i915_gem_exec_object2 *entry,
                                    struct drm_i915_gem_relocation_entry *reloc)
 {
         struct drm_device *dev = obj->base.dev;
@@ -411,10 +410,10 @@ i915_gem_execbuffer_relocate_entry(struct drm_i915_gem_object *obj,
 
 static int
 i915_gem_execbuffer_relocate_object(struct drm_i915_gem_object *obj,
-                                    struct eb_objects *eb,
-                                    struct drm_i915_gem_exec_object2 *entry)
+                                    struct eb_objects *eb)
 {
         struct drm_i915_gem_relocation_entry __user *user_relocs;
+        struct drm_i915_gem_exec_object2 *entry = obj->exec_entry;
         int i, ret;
 
         user_relocs = (void __user *)(uintptr_t)entry->relocs_ptr;
@@ -426,7 +425,7 @@ i915_gem_execbuffer_relocate_object(struct drm_i915_gem_object *obj,
                                               sizeof(reloc)))
                         return -EFAULT;
 
-                ret = i915_gem_execbuffer_relocate_entry(obj, eb, entry, &reloc);
+                ret = i915_gem_execbuffer_relocate_entry(obj, eb, &reloc);
                 if (ret)
                         return ret;
 
@@ -442,13 +441,13 @@ i915_gem_execbuffer_relocate_object(struct drm_i915_gem_object *obj,
 static int
 i915_gem_execbuffer_relocate_object_slow(struct drm_i915_gem_object *obj,
                                          struct eb_objects *eb,
-                                         struct drm_i915_gem_exec_object2 *entry,
                                          struct drm_i915_gem_relocation_entry *relocs)
 {
+        const struct drm_i915_gem_exec_object2 *entry = obj->exec_entry;
         int i, ret;
 
         for (i = 0; i < entry->relocation_count; i++) {
-                ret = i915_gem_execbuffer_relocate_entry(obj, eb, entry, &relocs[i]);
+                ret = i915_gem_execbuffer_relocate_entry(obj, eb, &relocs[i]);
                 if (ret)
                         return ret;
         }
@@ -459,8 +458,7 @@ i915_gem_execbuffer_relocate_object_slow(struct drm_i915_gem_object *obj,
 static int
 i915_gem_execbuffer_relocate(struct drm_device *dev,
                              struct eb_objects *eb,
-                             struct list_head *objects,
-                             struct drm_i915_gem_exec_object2 *exec)
+                             struct list_head *objects)
 {
         struct drm_i915_gem_object *obj;
         int ret;
@@ -468,7 +466,7 @@ i915_gem_execbuffer_relocate(struct drm_device *dev,
         list_for_each_entry(obj, objects, exec_list) {
                 obj->base.pending_read_domains = 0;
                 obj->base.pending_write_domain = 0;
-                ret = i915_gem_execbuffer_relocate_object(obj, eb, exec++);
+                ret = i915_gem_execbuffer_relocate_object(obj, eb);
                 if (ret)
                         return ret;
         }
@@ -479,13 +477,36 @@ i915_gem_execbuffer_relocate(struct drm_device *dev,
 static int
 i915_gem_execbuffer_reserve(struct intel_ring_buffer *ring,
                             struct drm_file *file,
-                            struct list_head *objects,
-                            struct drm_i915_gem_exec_object2 *exec)
+                            struct list_head *objects)
 {
         struct drm_i915_gem_object *obj;
-        struct drm_i915_gem_exec_object2 *entry;
         int ret, retry;
         bool has_fenced_gpu_access = INTEL_INFO(ring->dev)->gen < 4;
+        struct list_head ordered_objects;
+
+        INIT_LIST_HEAD(&ordered_objects);
+        while (!list_empty(objects)) {
+                struct drm_i915_gem_exec_object2 *entry;
+                bool need_fence, need_mappable;
+
+                obj = list_first_entry(objects,
+                                       struct drm_i915_gem_object,
+                                       exec_list);
+                entry = obj->exec_entry;
+
+                need_fence =
+                        has_fenced_gpu_access &&
+                        entry->flags & EXEC_OBJECT_NEEDS_FENCE &&
+                        obj->tiling_mode != I915_TILING_NONE;
+                need_mappable =
+                        entry->relocation_count ? true : need_fence;
+
+                if (need_mappable)
+                        list_move(&obj->exec_list, &ordered_objects);
+                else
+                        list_move_tail(&obj->exec_list, &ordered_objects);
+        }
+        list_splice(&ordered_objects, objects);
 
         /* Attempt to pin all of the buffers into the GTT.
          * This is done in 3 phases:
@@ -504,14 +525,11 @@ i915_gem_execbuffer_reserve(struct intel_ring_buffer *ring,
                 ret = 0;
 
                 /* Unbind any ill-fitting objects or pin. */
-                entry = exec;
                 list_for_each_entry(obj, objects, exec_list) {
+                        struct drm_i915_gem_exec_object2 *entry = obj->exec_entry;
                         bool need_fence, need_mappable;
-
-                        if (!obj->gtt_space) {
-                                entry++;
+                        if (!obj->gtt_space)
                                 continue;
-                        }
 
                         need_fence =
                                 has_fenced_gpu_access &&
@@ -534,8 +552,8 @@ i915_gem_execbuffer_reserve(struct intel_ring_buffer *ring,
                 }
 
                 /* Bind fresh objects */
-                entry = exec;
                 list_for_each_entry(obj, objects, exec_list) {
+                        struct drm_i915_gem_exec_object2 *entry = obj->exec_entry;
                         bool need_fence;
 
                         need_fence =
@@ -570,7 +588,6 @@ i915_gem_execbuffer_reserve(struct intel_ring_buffer *ring,
                         }
 
                         entry->offset = obj->gtt_offset;
-                        entry++;
                 }
 
                 /* Decrement pin count for bound objects */
@@ -680,10 +697,11 @@ i915_gem_execbuffer_relocate_slow(struct drm_device *dev,
 
                 list_add_tail(&obj->exec_list, objects);
                 obj->exec_handle = exec[i].handle;
+                obj->exec_entry = &exec[i];
                 eb_add_object(eb, obj);
         }
 
-        ret = i915_gem_execbuffer_reserve(ring, file, objects, exec);
+        ret = i915_gem_execbuffer_reserve(ring, file, objects);
         if (ret)
                 goto err;
 
@@ -692,7 +710,6 @@ i915_gem_execbuffer_relocate_slow(struct drm_device *dev,
                 obj->base.pending_read_domains = 0;
                 obj->base.pending_write_domain = 0;
                 ret = i915_gem_execbuffer_relocate_object_slow(obj, eb,
-                                                               exec,
                                                                reloc + total);
                 if (ret)
                         goto err;
@@ -1110,16 +1127,22 @@ i915_gem_do_execbuffer(struct drm_device *dev, void *data,
 
                 list_add_tail(&obj->exec_list, &objects);
                 obj->exec_handle = exec[i].handle;
+                obj->exec_entry = &exec[i];
                 eb_add_object(eb, obj);
         }
 
+        /* take note of the batch buffer before we might reorder the lists */
+        batch_obj = list_entry(objects.prev,
+                               struct drm_i915_gem_object,
+                               exec_list);
+
         /* Move the objects en-masse into the GTT, evicting if necessary. */
-        ret = i915_gem_execbuffer_reserve(ring, file, &objects, exec);
+        ret = i915_gem_execbuffer_reserve(ring, file, &objects);
         if (ret)
                 goto err;
 
         /* The objects are in their final locations, apply the relocations. */
-        ret = i915_gem_execbuffer_relocate(dev, eb, &objects, exec);
+        ret = i915_gem_execbuffer_relocate(dev, eb, &objects);
         if (ret) {
                 if (ret == -EFAULT) {
                         ret = i915_gem_execbuffer_relocate_slow(dev, file, ring,
@@ -1133,9 +1156,6 @@ i915_gem_do_execbuffer(struct drm_device *dev, void *data,
         }
 
         /* Set the pending read domains for the batch buffer to COMMAND */
-        batch_obj = list_entry(objects.prev,
-                               struct drm_i915_gem_object,
-                               exec_list);
         if (batch_obj->base.pending_write_domain) {
                 DRM_ERROR("Attempting to use self-modifying batch buffer\n");
                 ret = -EINVAL;