Re: [PATCH v2 4/6] drm/i915: Implement intersect/compatible functions

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Hi Matthew,

On 7/26/2022 4:11 PM, Matthew Auld wrote:
On 25/07/2022 12:42, Arunpravin Paneer Selvam wrote:
Implemented a new intersect and compatible callback function
fetching start offset from drm buddy allocator.

Signed-off-by: Christian König <christian.koenig@xxxxxxx>
Signed-off-by: Arunpravin Paneer Selvam <Arunpravin.PaneerSelvam@xxxxxxx>
---
  drivers/gpu/drm/i915/i915_ttm_buddy_manager.c | 43 +++++++++++++++++++
  1 file changed, 43 insertions(+)

diff --git a/drivers/gpu/drm/i915/i915_ttm_buddy_manager.c b/drivers/gpu/drm/i915/i915_ttm_buddy_manager.c
index a5109548abc0..b5801c05bd41 100644
--- a/drivers/gpu/drm/i915/i915_ttm_buddy_manager.c
+++ b/drivers/gpu/drm/i915/i915_ttm_buddy_manager.c
@@ -178,6 +178,47 @@ static void i915_ttm_buddy_man_free(struct ttm_resource_manager *man,
      kfree(bman_res);
  }
  +static bool i915_ttm_buddy_man_intersect(struct ttm_resource_manager *man,
+                     struct ttm_resource *res,
+                     const struct ttm_place *place,
+                     size_t size)
+{
+    struct i915_ttm_buddy_resource *bman_res = to_ttm_buddy_resource(res);
+    u32 start, num_pages = PFN_UP(size);
+    struct drm_buddy_block *block;
+
+    /* Check each drm buddy block individually */
+    list_for_each_entry(block, &bman_res->blocks, link) {
+        start = drm_buddy_block_offset(block) >> PAGE_SHIFT;
+        /* Don't evict BOs outside of the requested placement range */
+        if (place->fpfn >= (start + num_pages) ||
+            (place->lpfn && place->lpfn <= start))
+            return false;
+    }
+
+    return true;
+}

This looks like a nice idea. We should be able to clean up i915_ttm_eviction_valuable() a fair bit I think, if we now call ttm_bo_eviction_valuable() at the end (like in amdgpu), and move the bits that are specific to buddy_man here?

So something like:

if (!place->fpfn && !place->lpfn)
    return true;

if (!place->fpfn &&
    place->lpfn == i915_buddy_man_visible_size(man))
    return bman_res->used_visible_size > 0;

/* Check each drm buddy block individually */
....
modified in v3
+
+static bool i915_ttm_buddy_man_compatible(struct ttm_resource_manager *man,
+                      struct ttm_resource *res,
+                      const struct ttm_place *place,
+                      size_t size)

Is it not possible to derive the size from res->num_pages?
I think it is possible, I will check with Christian for any specific case that might
require ttm_buffer_object->base.size

+{
+    struct i915_ttm_buddy_resource *bman_res = to_ttm_buddy_resource(res);
+    u32 start, num_pages = PFN_UP(size);
+    struct drm_buddy_block *block;
+
+    /* Check each drm buddy block individually */
+    list_for_each_entry(block, &bman_res->blocks, link) {
+        start = drm_buddy_block_offset(block) >> PAGE_SHIFT;
+        if (start < place->fpfn ||
+            (place->lpfn && (start + num_pages) > place->lpfn))
+            return false;
+    }

if (!place->fpfn && !place->lpfn)
    return true;

if (!place->fpfn &&
    place->lpfn == i915_buddy_man_visible_size(man))
    return bman_res->used_visible_size == res->num_pages;

/* Check each drm buddy block individually */
...
modified in v3
+
+    return true;
+}
+
  static void i915_ttm_buddy_man_debug(struct ttm_resource_manager *man,
                       struct drm_printer *printer)
  {
@@ -205,6 +246,8 @@ static void i915_ttm_buddy_man_debug(struct ttm_resource_manager *man,   static const struct ttm_resource_manager_func i915_ttm_buddy_manager_func = {
      .alloc = i915_ttm_buddy_man_alloc,
      .free = i915_ttm_buddy_man_free,
+    .intersect = i915_ttm_buddy_man_intersect,

s/intersect/intersects/ ?
okay.
+    .compatible = i915_ttm_buddy_man_compatible,
      .debug = i915_ttm_buddy_man_debug,
  };




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