AFAICT the rationale for the loop is to:
1) try to allocate from the preferred order
2) if it fails, try higher orders (order + 1 -> max order)
3) if it fails, try smaller orders (order - 1 -> min order)
Steps 1 and 2 are covered by the loop going through [order, max_order].
Currently step 3 tries again [order, max_order] but with decreasing
values of order.
This is wasteful, so change it to evaluate only order.
Signed-off-by: Pierre-Eric Pelloux-Prayer <pierre-eric.pelloux-pra...@amd.com>
---
drivers/gpu/drm/drm_buddy.c | 17 ++++++++++++-----
1 file changed, 12 insertions(+), 5 deletions(-)
diff --git a/drivers/gpu/drm/drm_buddy.c b/drivers/gpu/drm/drm_buddy.c
index fd31322b3d41..9d3723f2cff9 100644
--- a/drivers/gpu/drm/drm_buddy.c
+++ b/drivers/gpu/drm/drm_buddy.c
@@ -590,13 +590,14 @@ __drm_buddy_alloc_range_bias(struct drm_buddy *mm,
static struct drm_buddy_block *
get_maxblock(struct drm_buddy *mm, unsigned int order,
+ unsigned int max_order,
unsigned long flags)
{
struct drm_buddy_block *max_block = NULL, *block = NULL;
bool wants_clear;
unsigned int i;
- for (i = order; i <= mm->max_order; ++i) {
+ for (i = order; i <= max_order; ++i) {
struct drm_buddy_block *tmp_block;
wants_clear = flags & DRM_BUDDY_PREFER_CLEAR_ALLOCATION;
@@ -635,6 +636,7 @@ get_maxblock(struct drm_buddy *mm, unsigned int order,
static struct drm_buddy_block *
alloc_from_freelist(struct drm_buddy *mm,
unsigned int order,
+ unsigned int max_order,
unsigned long flags)
{
struct drm_buddy_block *block = NULL;
@@ -643,12 +645,12 @@ alloc_from_freelist(struct drm_buddy *mm,
int err;
if (flags & DRM_BUDDY_TOPDOWN_ALLOCATION) {
- block = get_maxblock(mm, order, flags);
+ block = get_maxblock(mm, order, max_order, flags);
if (block)
/* Store the obtained block order */
tmp = drm_buddy_block_order(block);
} else {
- for (tmp = order; tmp <= mm->max_order; ++tmp) {
+ for (tmp = order; tmp <= max_order; ++tmp) {
struct drm_buddy_block *tmp_block;
wants_clear = flags & DRM_BUDDY_PREFER_CLEAR_ALLOCATION;
@@ -956,6 +958,7 @@ static struct drm_buddy_block *
__drm_buddy_alloc_blocks(struct drm_buddy *mm,
u64 start, u64 end,
unsigned int order,
+ unsigned int max_order,
unsigned long flags)
{
if (flags & DRM_BUDDY_RANGE_ALLOCATION)
@@ -964,7 +967,7 @@ __drm_buddy_alloc_blocks(struct drm_buddy *mm,
order, flags);
else
/* Allocate from freelist */
- return alloc_from_freelist(mm, order, flags);
+ return alloc_from_freelist(mm, order, max_order, flags);
}
/**
@@ -995,7 +998,7 @@ int drm_buddy_alloc_blocks(struct drm_buddy *mm,
{
struct drm_buddy_block *block = NULL;
u64 original_size, original_min_size;
- unsigned int min_order, order;
+ unsigned int min_order, max_order, order;
LIST_HEAD(allocated);
unsigned long pages;
int err;
@@ -1044,6 +1047,7 @@ int drm_buddy_alloc_blocks(struct drm_buddy *mm,
do {
order = min(order, (unsigned int)fls(pages) - 1);
+ max_order = mm->max_order;
BUG_ON(order > mm->max_order);
BUG_ON(order < min_order);
@@ -1051,6 +1055,7 @@ int drm_buddy_alloc_blocks(struct drm_buddy *mm,
block = __drm_buddy_alloc_blocks(mm, start,
end,
order,
+ max_order,
flags);
if (!IS_ERR(block))
break;
@@ -1062,6 +1067,7 @@ int drm_buddy_alloc_blocks(struct drm_buddy *mm,
block = __drm_buddy_alloc_blocks(mm,
start,
end,
min_order,
+
mm->max_order,
flags);
if (!IS_ERR(block)) {
order = min_order;
@@ -1082,6 +1088,7 @@ int drm_buddy_alloc_blocks(struct drm_buddy *mm,
err = -ENOSPC;
goto err_free;
}
+ max_order = order;
} while (1);
mark_allocated(block);
--
2.43.0
