[PATCH v2 1/3] drm/buddy: Improve contiguous memory allocation
Arunpravin Paneer Selvam
Arunpravin.PaneerSelvam at amd.com
Sat Sep 9 16:09:00 UTC 2023
Problem statement: The current method roundup_power_of_two()
to allocate contiguous address triggers -ENOSPC in some cases
even though we have enough free spaces and so to help with
that we introduce a try harder mechanism.
In case of -ENOSPC, the new try harder mechanism rounddown the
original size to power of 2 and iterating over the round down
sized freelist blocks to allocate the required size traversing
RHS and LHS.
As part of the above new method implementation we moved
contiguous/alignment size computation part and trim function
to the drm buddy file.
v2: Modify the alloc_range() function to return total allocated size
on -ENOSPC err and traverse RHS/LHS to allocate the required
size (Matthew).
Signed-off-by: Arunpravin Paneer Selvam <Arunpravin.PaneerSelvam at amd.com>
---
drivers/gpu/drm/drm_buddy.c | 138 ++++++++++++++++++++++++++++++++----
include/drm/drm_buddy.h | 6 +-
2 files changed, 127 insertions(+), 17 deletions(-)
diff --git a/drivers/gpu/drm/drm_buddy.c b/drivers/gpu/drm/drm_buddy.c
index 7098f125b54a..e909eed9cf60 100644
--- a/drivers/gpu/drm/drm_buddy.c
+++ b/drivers/gpu/drm/drm_buddy.c
@@ -480,10 +480,12 @@ alloc_from_freelist(struct drm_buddy *mm,
static int __alloc_range(struct drm_buddy *mm,
struct list_head *dfs,
u64 start, u64 size,
- struct list_head *blocks)
+ struct list_head *blocks,
+ u64 *total_allocated_on_err)
{
struct drm_buddy_block *block;
struct drm_buddy_block *buddy;
+ u64 total_allocated = 0;
LIST_HEAD(allocated);
u64 end;
int err;
@@ -520,6 +522,7 @@ static int __alloc_range(struct drm_buddy *mm,
}
mark_allocated(block);
+ total_allocated += drm_buddy_block_size(mm, block);
mm->avail -= drm_buddy_block_size(mm, block);
list_add_tail(&block->link, &allocated);
continue;
@@ -551,13 +554,20 @@ static int __alloc_range(struct drm_buddy *mm,
__drm_buddy_free(mm, block);
err_free:
- drm_buddy_free_list(mm, &allocated);
+ if (err == -ENOSPC && total_allocated_on_err) {
+ list_splice_tail(&allocated, blocks);
+ *total_allocated_on_err = total_allocated;
+ } else {
+ drm_buddy_free_list(mm, &allocated);
+ }
+
return err;
}
static int __drm_buddy_alloc_range(struct drm_buddy *mm,
u64 start,
u64 size,
+ u64 *total_allocated_on_err,
struct list_head *blocks)
{
LIST_HEAD(dfs);
@@ -566,7 +576,62 @@ static int __drm_buddy_alloc_range(struct drm_buddy *mm,
for (i = 0; i < mm->n_roots; ++i)
list_add_tail(&mm->roots[i]->tmp_link, &dfs);
- return __alloc_range(mm, &dfs, start, size, blocks);
+ return __alloc_range(mm, &dfs, start, size,
+ blocks, total_allocated_on_err);
+}
+
+static int __alloc_contig_try_harder(struct drm_buddy *mm,
+ u64 size,
+ u64 min_block_size,
+ struct list_head *blocks)
+{
+ u64 rhs_offset, lhs_offset, lhs_size, filled;
+ struct drm_buddy_block *block;
+ struct list_head *list;
+ LIST_HEAD(blocks_lhs);
+ unsigned long pages;
+ unsigned int order;
+ u64 modify_size;
+ int err;
+
+ modify_size = rounddown_pow_of_two(size);
+ pages = modify_size >> ilog2(mm->chunk_size);
+ order = fls(pages) - 1;
+ if (order == 0)
+ return -ENOSPC;
+
+ list = &mm->free_list[order];
+ if (list_empty(list))
+ return -ENOSPC;
+
+ list_for_each_entry_reverse(block, list, link) {
+ /* Allocate blocks traversing RHS */
+ rhs_offset = drm_buddy_block_offset(block);
+ err = __drm_buddy_alloc_range(mm, rhs_offset, size,
+ &filled, blocks);
+ if (!err || err != -ENOSPC)
+ return err;
+
+ lhs_size = max((size - filled), min_block_size);
+ if (!IS_ALIGNED(lhs_size, min_block_size))
+ lhs_size = round_up(lhs_size, min_block_size);
+
+ /* Allocate blocks traversing LHS */
+ lhs_offset = drm_buddy_block_offset(block) - lhs_size;
+ err = __drm_buddy_alloc_range(mm, lhs_offset, lhs_size,
+ NULL, &blocks_lhs);
+ if (!err) {
+ list_splice(&blocks_lhs, blocks);
+ return 0;
+ } else if (err != -ENOSPC) {
+ drm_buddy_free_list(mm, blocks);
+ return err;
+ }
+ /* Free blocks for the next iteration */
+ drm_buddy_free_list(mm, blocks);
+ }
+
+ return -ENOSPC;
}
/**
@@ -626,7 +691,7 @@ int drm_buddy_block_trim(struct drm_buddy *mm,
new_start = drm_buddy_block_offset(block);
list_add(&block->tmp_link, &dfs);
- err = __alloc_range(mm, &dfs, new_start, new_size, blocks);
+ err = __alloc_range(mm, &dfs, new_start, new_size, blocks, NULL);
if (err) {
mark_allocated(block);
mm->avail -= drm_buddy_block_size(mm, block);
@@ -645,7 +710,7 @@ EXPORT_SYMBOL(drm_buddy_block_trim);
* @start: start of the allowed range for this block
* @end: end of the allowed range for this block
* @size: size of the allocation
- * @min_page_size: alignment of the allocation
+ * @min_block_size: alignment of the allocation
* @blocks: output list head to add allocated blocks
* @flags: DRM_BUDDY_*_ALLOCATION flags
*
@@ -660,23 +725,24 @@ EXPORT_SYMBOL(drm_buddy_block_trim);
*/
int drm_buddy_alloc_blocks(struct drm_buddy *mm,
u64 start, u64 end, u64 size,
- u64 min_page_size,
+ u64 min_block_size,
struct list_head *blocks,
unsigned long flags)
{
struct drm_buddy_block *block = NULL;
+ u64 original_size, original_min_size;
unsigned int min_order, order;
- unsigned long pages;
LIST_HEAD(allocated);
+ unsigned long pages;
int err;
if (size < mm->chunk_size)
return -EINVAL;
- if (min_page_size < mm->chunk_size)
+ if (min_block_size < mm->chunk_size)
return -EINVAL;
- if (!is_power_of_2(min_page_size))
+ if (!is_power_of_2(min_block_size))
return -EINVAL;
if (!IS_ALIGNED(start | end | size, mm->chunk_size))
@@ -690,14 +756,23 @@ int drm_buddy_alloc_blocks(struct drm_buddy *mm,
/* Actual range allocation */
if (start + size == end)
- return __drm_buddy_alloc_range(mm, start, size, blocks);
-
- if (!IS_ALIGNED(size, min_page_size))
- return -EINVAL;
+ return __drm_buddy_alloc_range(mm, start, size, NULL, blocks);
+
+ original_size = size;
+ original_min_size = min_block_size;
+
+ /* Roundup the size to power of 2 */
+ if (flags & DRM_BUDDY_CONTIGUOUS_ALLOCATION) {
+ size = roundup_pow_of_two(size);
+ min_block_size = size;
+ /* Align size value to min_block_size */
+ } else if (!IS_ALIGNED(size, min_block_size)) {
+ size = round_up(size, min_block_size);
+ }
pages = size >> ilog2(mm->chunk_size);
order = fls(pages) - 1;
- min_order = ilog2(min_page_size) - ilog2(mm->chunk_size);
+ min_order = ilog2(min_block_size) - ilog2(mm->chunk_size);
do {
order = min(order, (unsigned int)fls(pages) - 1);
@@ -716,6 +791,16 @@ int drm_buddy_alloc_blocks(struct drm_buddy *mm,
break;
if (order-- == min_order) {
+ if (flags & DRM_BUDDY_CONTIGUOUS_ALLOCATION &&
+ !(flags & DRM_BUDDY_RANGE_ALLOCATION))
+ /*
+ * Try contiguous block allocation through
+ * try harder method
+ */
+ return __alloc_contig_try_harder(mm,
+ original_size,
+ original_min_size,
+ blocks);
err = -ENOSPC;
goto err_free;
}
@@ -732,6 +817,31 @@ int drm_buddy_alloc_blocks(struct drm_buddy *mm,
break;
} while (1);
+ /* Trim the allocated block to the required size */
+ if (original_size != size) {
+ struct list_head *trim_list;
+ LIST_HEAD(temp);
+ u64 trim_size;
+
+ trim_list = &allocated;
+ trim_size = original_size;
+
+ if (!list_is_singular(&allocated)) {
+ block = list_last_entry(&allocated, typeof(*block), link);
+ list_move(&block->link, &temp);
+ trim_list = &temp;
+ trim_size = drm_buddy_block_size(mm, block) -
+ (size - original_size);
+ }
+
+ drm_buddy_block_trim(mm,
+ trim_size,
+ trim_list);
+
+ if (!list_empty(&temp))
+ list_splice_tail(trim_list, &allocated);
+ }
+
list_splice_tail(&allocated, blocks);
return 0;
diff --git a/include/drm/drm_buddy.h b/include/drm/drm_buddy.h
index 572077ff8ae7..a5b39fc01003 100644
--- a/include/drm/drm_buddy.h
+++ b/include/drm/drm_buddy.h
@@ -22,8 +22,9 @@
start__ >= max__ || size__ > max__ - start__; \
})
-#define DRM_BUDDY_RANGE_ALLOCATION (1 << 0)
-#define DRM_BUDDY_TOPDOWN_ALLOCATION (1 << 1)
+#define DRM_BUDDY_RANGE_ALLOCATION BIT(0)
+#define DRM_BUDDY_TOPDOWN_ALLOCATION BIT(1)
+#define DRM_BUDDY_CONTIGUOUS_ALLOCATION BIT(2)
struct drm_buddy_block {
#define DRM_BUDDY_HEADER_OFFSET GENMASK_ULL(63, 12)
@@ -155,5 +156,4 @@ void drm_buddy_print(struct drm_buddy *mm, struct drm_printer *p);
void drm_buddy_block_print(struct drm_buddy *mm,
struct drm_buddy_block *block,
struct drm_printer *p);
-
#endif
--
2.25.1
More information about the dri-devel
mailing list