Hi,

On 14/12/15 11:36, Chris Wilson wrote:
Hook the vma itself into the i915_gem_request_retire() so that we can
accurately track when a solitary vma is inactive (as opposed to having

s/solitary/individual/ ?

to wait for the entire object to be idle). This improves the interaction
when using multiple contexts (with full-ppgtt) and eliminates some
frequent list walking.

What list walking are you referring to? Maybe clarify in the commit message.

Anyway, looks surprisingly simple. Almost suspiciously simple, but I can't fault it:

Reviewed-by: Tvrtko Ursulin <[email protected]>

Regards,

Tvrtko


A side-effect is that we get an active vma reference for free. The
consequence of this is shown in the next patch...

Signed-off-by: Chris Wilson <[email protected]>
---
  drivers/gpu/drm/i915/i915_debugfs.c        |  2 +-
  drivers/gpu/drm/i915/i915_gem.c            | 36 ++++++++++++++++--------------
  drivers/gpu/drm/i915/i915_gem_execbuffer.c |  2 ++
  drivers/gpu/drm/i915/i915_gem_gtt.c        | 20 +++++++++++++++++
  drivers/gpu/drm/i915/i915_gem_gtt.h        |  5 +++++
  5 files changed, 47 insertions(+), 18 deletions(-)

diff --git a/drivers/gpu/drm/i915/i915_debugfs.c 
b/drivers/gpu/drm/i915/i915_debugfs.c
index 179e3c5c5022..4df4ebbd56d6 100644
--- a/drivers/gpu/drm/i915/i915_debugfs.c
+++ b/drivers/gpu/drm/i915/i915_debugfs.c
@@ -356,7 +356,7 @@ static int per_file_stats(int id, void *ptr, void *data)
                                continue;
                }

-               if (obj->active) /* XXX per-vma statistic */
+               if (vma->active)
                        stats->active += vma->node.size;
                else
                        stats->inactive += vma->node.size;
diff --git a/drivers/gpu/drm/i915/i915_gem.c b/drivers/gpu/drm/i915/i915_gem.c
index 8a824c5d5348..1d21c5b79215 100644
--- a/drivers/gpu/drm/i915/i915_gem.c
+++ b/drivers/gpu/drm/i915/i915_gem.c
@@ -2040,7 +2040,6 @@ i915_gem_object_retire__read(struct 
drm_i915_gem_request_active *active,
        int ring = request->engine->id;
        struct drm_i915_gem_object *obj =
                container_of(active, struct drm_i915_gem_object, 
last_read[ring]);
-       struct i915_vma *vma;

        RQ_BUG_ON((obj->flags & (1 << (ring + I915_BO_ACTIVE_SHIFT))) == 0);

@@ -2052,12 +2051,9 @@ i915_gem_object_retire__read(struct 
drm_i915_gem_request_active *active,
         * so that we don't steal from recently used but inactive objects
         * (unless we are forced to ofc!)
         */
-       list_move_tail(&obj->global_list, &request->i915->mm.bound_list);
-
-       list_for_each_entry(vma, &obj->vma_list, obj_link) {
-               if (!list_empty(&vma->vm_link))
-                       list_move_tail(&vma->vm_link, &vma->vm->inactive_list);
-       }
+       if (!list_empty(&obj->vma_list))
+               list_move_tail(&obj->global_list,
+                              &request->i915->mm.bound_list);

        drm_gem_object_unreference(&obj->base);
  }
@@ -2567,7 +2563,19 @@ static int __i915_vma_unbind(struct i915_vma *vma, bool 
wait)
  {
        struct drm_i915_gem_object *obj = vma->obj;
        struct drm_i915_private *dev_priv = obj->base.dev->dev_private;
-       int ret;
+       int ret, i;
+
+       /* First wait upon any activity as retiring the request may
+        * have side-effects such as unpinning or even unbinding this vma.
+        */
+       if (vma->active && wait) {
+               for (i = 0; i < ARRAY_SIZE(vma->last_read); i++) {
+                       ret = i915_wait_request(vma->last_read[i].request);
+                       if (ret)
+                               return ret;
+               }
+               RQ_BUG_ON(vma->active);
+       }

        if (list_empty(&vma->obj_link))
                return 0;
@@ -2582,12 +2590,6 @@ static int __i915_vma_unbind(struct i915_vma *vma, bool 
wait)

        BUG_ON(obj->pages == NULL);

-       if (wait) {
-               ret = i915_gem_object_wait_rendering(obj, false);
-               if (ret)
-                       return ret;
-       }
-
        if (vma->is_ggtt && vma->ggtt_view.type == I915_GGTT_VIEW_NORMAL) {
                i915_gem_object_finish_gtt(obj);

@@ -3023,9 +3025,8 @@ i915_gem_object_set_to_gtt_domain(struct 
drm_i915_gem_object *obj, bool write)

        /* And bump the LRU for this access */
        vma = i915_gem_obj_to_ggtt(obj);
-       if (vma && drm_mm_node_allocated(&vma->node) && !obj->active)
-               list_move_tail(&vma->vm_link,
-                              &to_i915(obj->base.dev)->gtt.base.inactive_list);
+       if (vma && drm_mm_node_allocated(&vma->node) && !vma->active)
+               list_move_tail(&vma->vm_link, &vma->vm->inactive_list);

        return 0;
  }
@@ -3874,6 +3875,7 @@ struct i915_vma *i915_gem_obj_to_ggtt_view(struct 
drm_i915_gem_object *obj,
  void i915_gem_vma_destroy(struct i915_vma *vma)
  {
        WARN_ON(vma->node.allocated);
+       RQ_BUG_ON(vma->active);

        /* Keep the vma as a placeholder in the execbuffer reservation lists */
        if (!list_empty(&vma->exec_list))
diff --git a/drivers/gpu/drm/i915/i915_gem_execbuffer.c 
b/drivers/gpu/drm/i915/i915_gem_execbuffer.c
index 6de8681bb64c..1d4378a4501e 100644
--- a/drivers/gpu/drm/i915/i915_gem_execbuffer.c
+++ b/drivers/gpu/drm/i915/i915_gem_execbuffer.c
@@ -1099,6 +1099,8 @@ void i915_vma_move_to_active(struct i915_vma *vma,
                }
        }

+       vma->active |= 1 << engine;
+       i915_gem_request_mark_active(req, &vma->last_read[engine]);
        list_move_tail(&vma->vm_link, &vma->vm->active_list);
  }

diff --git a/drivers/gpu/drm/i915/i915_gem_gtt.c 
b/drivers/gpu/drm/i915/i915_gem_gtt.c
index 130ccefb2491..5505603f52af 100644
--- a/drivers/gpu/drm/i915/i915_gem_gtt.c
+++ b/drivers/gpu/drm/i915/i915_gem_gtt.c
@@ -3225,12 +3225,30 @@ void i915_gem_restore_gtt_mappings(struct drm_device 
*dev)
        i915_ggtt_flush(dev_priv);
  }

+static void
+i915_vma_retire(struct drm_i915_gem_request_active *active,
+               struct drm_i915_gem_request *rq)
+{
+       const unsigned engine = rq->engine->id;
+       struct i915_vma *vma =
+               container_of(active, struct i915_vma, last_read[engine]);
+
+       RQ_BUG_ON((vma->obj->active & (1 << engine)) == 0);
+
+       vma->active &= ~(1 << engine);
+       if (vma->active)
+               return;
+
+       list_move_tail(&vma->vm_link, &vma->vm->inactive_list);
+}
+
  static struct i915_vma *
  __i915_gem_vma_create(struct drm_i915_gem_object *obj,
                      struct i915_address_space *vm,
                      const struct i915_ggtt_view *ggtt_view)
  {
        struct i915_vma *vma;
+       int i;

        if (WARN_ON(i915_is_ggtt(vm) != !!ggtt_view))
                return ERR_PTR(-EINVAL);
@@ -3242,6 +3260,8 @@ __i915_gem_vma_create(struct drm_i915_gem_object *obj,
        INIT_LIST_HEAD(&vma->vm_link);
        INIT_LIST_HEAD(&vma->obj_link);
        INIT_LIST_HEAD(&vma->exec_list);
+       for (i = 0; i < ARRAY_SIZE(vma->last_read); i++)
+               init_request_active(&vma->last_read[i], i915_vma_retire);
        vma->vm = vm;
        vma->obj = obj;
        vma->is_ggtt = i915_is_ggtt(vm);
diff --git a/drivers/gpu/drm/i915/i915_gem_gtt.h 
b/drivers/gpu/drm/i915/i915_gem_gtt.h
index 4e9553ace33f..c2f2c62ac88d 100644
--- a/drivers/gpu/drm/i915/i915_gem_gtt.h
+++ b/drivers/gpu/drm/i915/i915_gem_gtt.h
@@ -34,6 +34,8 @@
  #ifndef __I915_GEM_GTT_H__
  #define __I915_GEM_GTT_H__

+#include "i915_gem_request.h"
+
  struct drm_i915_file_private;

  typedef uint32_t gen6_pte_t;
@@ -180,10 +182,13 @@ struct i915_vma {
        struct drm_i915_gem_object *obj;
        struct i915_address_space *vm;

+       struct drm_i915_gem_request_active last_read[I915_NUM_RINGS];
+
        /** Flags and address space this VMA is bound to */
  #define GLOBAL_BIND   (1<<0)
  #define LOCAL_BIND    (1<<1)
        unsigned int bound : 4;
+       unsigned int active : I915_NUM_RINGS;
        bool is_ggtt : 1;

        /**

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