[PATCH v2 1/3] drm/buddy: Improve contiguous memory allocation
Arunpravin Paneer Selvam
arunpravin.paneerselvam at amd.com
Wed Sep 13 14:56:07 UTC 2023
On 11/09/23 03:46, Matthew Auld wrote:
> On 09/09/2023 17:09, Arunpravin Paneer Selvam wrote:
>> 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;
>
> I guess we could attempt to trim this also (could tweak the trim to
> work on multiple nodes)? But I guess in practice should be pretty meh,
> given that the extra rhs is hopefully not too big in the corner case
> where the alignment doesn't fit the min_block_size?
Thanks for the review. good point. I will take a look into it.
Regards,
Arun.
>
> Anyway, for patches 1-3,
> Reviewed-by: Matthew Auld <matthew.auld at intel.com>
>
>> + } 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
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