diff options
| -rw-r--r-- | src/gallium/drivers/nouveau/nouveau_heap.h | 20 |
1 files changed, 20 insertions, 0 deletions
diff --git a/src/gallium/drivers/nouveau/nouveau_heap.h b/src/gallium/drivers/nouveau/nouveau_heap.h index d0b22844ad0..a3d64a65623 100644 --- a/src/gallium/drivers/nouveau/nouveau_heap.h +++ b/src/gallium/drivers/nouveau/nouveau_heap.h @@ -23,6 +23,26 @@ #ifndef __NOUVEAU_HEAP_H__ #define __NOUVEAU_HEAP_H__ +/* This datastructure represents a memory allocation heap. Fundamentally, this + * is a doubly-linked list with a few properties, and a usage convention. + * + * On initial allocation, there is a single node with the full size that's + * marked as not in-use. As allocations are made, blocks are taken off the end + * of that first node, and inserted right after it. If the first node doesn't + * have enough free space, we look for free space down in the rest of the + * list. This can happen if an allocation is made and then freed. + * + * The first node will remain with in_use == 0 even if the whole heap is + * exhausted. Another invariant is that there will never be two sequential + * in_use == 0 nodes. If a node is freed and it has one (or both) adjacent + * free nodes, they are merged into one, and the relevant heap entries are + * freed. + * + * The pattern to free the whole heap is to start with the first node and then + * just free the "next" node, until there is no next node. This should assure + * that at the end the first (and only) node is not in use and contains the + * full size of the heap. + */ struct nouveau_heap { struct nouveau_heap *prev; struct nouveau_heap *next; |