[PATCH v3 1/2] drm/buddy: Implement tracking clear page feature
Arunpravin Paneer Selvam
arunpravin.paneerselvam at amd.com
Thu Dec 21 10:31:23 UTC 2023
Hi Matthew,
On 12/21/2023 12:51 AM, Matthew Auld wrote:
> Hi,
>
> On 14/12/2023 13:42, Arunpravin Paneer Selvam wrote:
>> - Add tracking clear page feature.
>>
>> - Driver should enable the DRM_BUDDY_CLEARED flag if it
>> successfully clears the blocks in the free path. On the otherhand,
>> DRM buddy marks each block as cleared.
>>
>> - Track the available cleared pages size
>>
>> - If driver requests cleared memory we prefer cleared memory
>> but fallback to uncleared if we can't find the cleared blocks.
>> when driver requests uncleared memory we try to use uncleared but
>> fallback to cleared memory if necessary.
>>
>> - When a block gets freed we clear it and mark the freed block as
>> cleared,
>> when there are buddies which are cleared as well we can merge them.
>> Otherwise, we prefer to keep the blocks as separated.
>
> I was not involved, but it looks like we have also tried enabling the
> clear-on-free idea for VRAM in i915 and then also tracking that in the
> allocator, however that work unfortunately is not upstream. The code
> is open source though:
> https://github.com/intel-gpu/intel-gpu-i915-backports/blob/backport/main/drivers/gpu/drm/i915/i915_buddy.c#L300
>
> It looks like some of the design differences there are having two
> separate free lists, so mm->clean and mm->dirty (sounds reasonable to
> me). And also the inclusion of a de-fragmentation routine, since buddy
> blocks are now not always merged back, we might choose to run the
> defrag in some cases, which also sounds reasonable. IIRC in amdgpu
> userspace can control the page-size for an allocation, so perhaps you
> would want to run it first if the allocation fails, before trying to
> evict stuff?
Thanks, I will check the code.
Regards,
Arun.
>
>>
>> v1: (Christian)
>> - Depends on the flag check DRM_BUDDY_CLEARED, enable the block as
>> cleared. Else, reset the clear flag for each block in the list.
>>
>> - For merging the 2 cleared blocks compare as below,
>> drm_buddy_is_clear(block) != drm_buddy_is_clear(buddy)
>>
>> Signed-off-by: Arunpravin Paneer Selvam
>> <Arunpravin.PaneerSelvam at amd.com>
>> Suggested-by: Christian König <christian.koenig at amd.com>
>> ---
>> drivers/gpu/drm/amd/amdgpu/amdgpu_vram_mgr.c | 6 +-
>> drivers/gpu/drm/drm_buddy.c | 169 +++++++++++++++---
>> drivers/gpu/drm/i915/i915_ttm_buddy_manager.c | 6 +-
>> drivers/gpu/drm/tests/drm_buddy_test.c | 10 +-
>> include/drm/drm_buddy.h | 18 +-
>> 5 files changed, 168 insertions(+), 41 deletions(-)
>>
>> diff --git a/drivers/gpu/drm/amd/amdgpu/amdgpu_vram_mgr.c
>> b/drivers/gpu/drm/amd/amdgpu/amdgpu_vram_mgr.c
>> index 08916538a615..d0e199cc8f17 100644
>> --- a/drivers/gpu/drm/amd/amdgpu/amdgpu_vram_mgr.c
>> +++ b/drivers/gpu/drm/amd/amdgpu/amdgpu_vram_mgr.c
>> @@ -556,7 +556,7 @@ static int amdgpu_vram_mgr_new(struct
>> ttm_resource_manager *man,
>> return 0;
>> error_free_blocks:
>> - drm_buddy_free_list(mm, &vres->blocks);
>> + drm_buddy_free_list(mm, &vres->blocks, 0);
>> mutex_unlock(&mgr->lock);
>> error_fini:
>> ttm_resource_fini(man, &vres->base);
>> @@ -589,7 +589,7 @@ static void amdgpu_vram_mgr_del(struct
>> ttm_resource_manager *man,
>> amdgpu_vram_mgr_do_reserve(man);
>> - drm_buddy_free_list(mm, &vres->blocks);
>> + drm_buddy_free_list(mm, &vres->blocks, 0);
>> mutex_unlock(&mgr->lock);
>> atomic64_sub(vis_usage, &mgr->vis_usage);
>> @@ -897,7 +897,7 @@ void amdgpu_vram_mgr_fini(struct amdgpu_device
>> *adev)
>> kfree(rsv);
>> list_for_each_entry_safe(rsv, temp, &mgr->reserved_pages,
>> blocks) {
>> - drm_buddy_free_list(&mgr->mm, &rsv->allocated);
>> + drm_buddy_free_list(&mgr->mm, &rsv->allocated, 0);
>> kfree(rsv);
>> }
>> if (!adev->gmc.is_app_apu)
>> diff --git a/drivers/gpu/drm/drm_buddy.c b/drivers/gpu/drm/drm_buddy.c
>> index f57e6d74fb0e..d44172f23f05 100644
>> --- a/drivers/gpu/drm/drm_buddy.c
>> +++ b/drivers/gpu/drm/drm_buddy.c
>> @@ -57,6 +57,16 @@ static void list_insert_sorted(struct drm_buddy *mm,
>> __list_add(&block->link, node->link.prev, &node->link);
>> }
>> +static void clear_reset(struct drm_buddy_block *block)
>> +{
>> + block->header &= ~DRM_BUDDY_HEADER_CLEAR;
>> +}
>> +
>> +static void mark_cleared(struct drm_buddy_block *block)
>> +{
>> + block->header |= DRM_BUDDY_HEADER_CLEAR;
>> +}
>> +
>> static void mark_allocated(struct drm_buddy_block *block)
>> {
>> block->header &= ~DRM_BUDDY_HEADER_STATE;
>> @@ -223,6 +233,12 @@ static int split_block(struct drm_buddy *mm,
>> mark_free(mm, block->left);
>> mark_free(mm, block->right);
>> + if (drm_buddy_block_is_clear(block)) {
>> + mark_cleared(block->left);
>> + mark_cleared(block->right);
>> + clear_reset(block);
>> + }
>> +
>> mark_split(block);
>> return 0;
>> @@ -273,6 +289,13 @@ static void __drm_buddy_free(struct drm_buddy *mm,
>> if (!drm_buddy_block_is_free(buddy))
>> break;
>> + if (drm_buddy_block_is_clear(block) !=
>> + drm_buddy_block_is_clear(buddy))
>> + break;
>> +
>> + if (drm_buddy_block_is_clear(block))
>> + mark_cleared(parent);
>> +
>> list_del(&buddy->link);
>> drm_block_free(mm, block);
>> @@ -295,6 +318,9 @@ void drm_buddy_free_block(struct drm_buddy *mm,
>> {
>> BUG_ON(!drm_buddy_block_is_allocated(block));
>> mm->avail += drm_buddy_block_size(mm, block);
>> + if (drm_buddy_block_is_clear(block))
>> + mm->clear_avail += drm_buddy_block_size(mm, block);
>> +
>> __drm_buddy_free(mm, block);
>> }
>> EXPORT_SYMBOL(drm_buddy_free_block);
>> @@ -305,10 +331,20 @@ EXPORT_SYMBOL(drm_buddy_free_block);
>> * @mm: DRM buddy manager
>> * @objects: input list head to free blocks
>> */
>> -void drm_buddy_free_list(struct drm_buddy *mm, struct list_head
>> *objects)
>> +void drm_buddy_free_list(struct drm_buddy *mm,
>> + struct list_head *objects,
>> + unsigned long flags)
>> {
>> struct drm_buddy_block *block, *on;
>> + if (flags & DRM_BUDDY_CLEARED) {
>> + list_for_each_entry(block, objects, link)
>> + mark_cleared(block);
>> + } else {
>> + list_for_each_entry(block, objects, link)
>> + clear_reset(block);
>> + }
>> +
>> list_for_each_entry_safe(block, on, objects, link) {
>> drm_buddy_free_block(mm, block);
>> cond_resched();
>> @@ -328,9 +364,11 @@ static inline bool contains(u64 s1, u64 e1, u64
>> s2, u64 e2)
>> }
>> static struct drm_buddy_block *
>> -alloc_range_bias(struct drm_buddy *mm,
>> - u64 start, u64 end,
>> - unsigned int order)
>> +__alloc_range_bias(struct drm_buddy *mm,
>> + u64 start, u64 end,
>> + unsigned int order,
>> + unsigned long flags,
>> + bool fallback)
>> {
>> struct drm_buddy_block *block;
>> struct drm_buddy_block *buddy;
>> @@ -369,6 +407,15 @@ alloc_range_bias(struct drm_buddy *mm,
>> if (contains(start, end, block_start, block_end) &&
>> order == drm_buddy_block_order(block)) {
>> + if (!fallback) {
>> + if (flags & DRM_BUDDY_CLEAR_ALLOCATION) {
>> + if (!drm_buddy_block_is_clear(block))
>> + continue;
>> + } else {
>> + if (drm_buddy_block_is_clear(block))
>> + continue;
>> + }
>> + }
>> /*
>> * Find the free block within the range.
>> */
>> @@ -405,25 +452,58 @@ alloc_range_bias(struct drm_buddy *mm,
>> }
>> static struct drm_buddy_block *
>> -get_maxblock(struct drm_buddy *mm, unsigned int order)
>> +__drm_buddy_alloc_range_bias(struct drm_buddy *mm,
>> + u64 start, u64 end,
>> + unsigned int order,
>> + unsigned long flags)
>> +{
>> + struct drm_buddy_block *block;
>> + bool fallback = 0;
>> +
>> + block = __alloc_range_bias(mm, start, end, order,
>> + flags, fallback);
>> + if (IS_ERR(block))
>> + return __alloc_range_bias(mm, start, end, order,
>> + flags, !fallback);
>> +
>> + return block;
>> +}
>> +
>> +static struct drm_buddy_block *
>> +get_maxblock(struct drm_buddy *mm, unsigned int order,
>> + unsigned long flags)
>> {
>> - struct drm_buddy_block *max_block = NULL, *node;
>> + struct drm_buddy_block *max_block = NULL, *block = NULL;
>> unsigned int i;
>> for (i = order; i <= mm->max_order; ++i) {
>> - if (!list_empty(&mm->free_list[i])) {
>> - node = list_last_entry(&mm->free_list[i],
>> - struct drm_buddy_block,
>> - link);
>> - if (!max_block) {
>> - max_block = node;
>> - continue;
>> + struct drm_buddy_block *tmp_block;
>> +
>> + list_for_each_entry_reverse(tmp_block, &mm->free_list[i],
>> link) {
>> + if (flags & DRM_BUDDY_CLEAR_ALLOCATION) {
>> + /* Find a cleared block */
>> + if (!drm_buddy_block_is_clear(tmp_block))
>> + continue;
>> + } else {
>> + if (drm_buddy_block_is_clear(tmp_block))
>> + continue;
>> }
>> - if (drm_buddy_block_offset(node) >
>> - drm_buddy_block_offset(max_block)) {
>> - max_block = node;
>> - }
>> + block = tmp_block;
>> + break;
>> + }
>> +
>> + if (!block)
>> + continue;
>> +
>> + if (!max_block) {
>> + max_block = block;
>> + continue;
>> + }
>> +
>> + if (drm_buddy_block_offset(block) >
>> + drm_buddy_block_offset(max_block)) {
>> + max_block = block;
>> }
>> }
>> @@ -440,11 +520,35 @@ alloc_from_freelist(struct drm_buddy *mm,
>> int err;
>> if (flags & DRM_BUDDY_TOPDOWN_ALLOCATION) {
>> - block = get_maxblock(mm, order);
>> + block = get_maxblock(mm, order, flags);
>> if (block)
>> /* Store the obtained block order */
>> tmp = drm_buddy_block_order(block);
>> } else {
>> + for (tmp = order; tmp <= mm->max_order; ++tmp) {
>> + struct drm_buddy_block *tmp_block;
>> +
>> + list_for_each_entry_reverse(tmp_block,
>> &mm->free_list[tmp], link) {
>> + if (flags & DRM_BUDDY_CLEAR_ALLOCATION) {
>> + /* Find a cleared block */
>> + if (!drm_buddy_block_is_clear(tmp_block))
>> + continue;
>> + } else {
>> + if (drm_buddy_block_is_clear(tmp_block))
>> + continue;
>> + }
>> +
>> + block = tmp_block;
>> + break;
>> + }
>> +
>> + if (block)
>> + break;
>> + }
>> + }
>> +
>> + if (!block) {
>> + /* Fallback method */
>> for (tmp = order; tmp <= mm->max_order; ++tmp) {
>> if (!list_empty(&mm->free_list[tmp])) {
>> block = list_last_entry(&mm->free_list[tmp],
>> @@ -454,10 +558,10 @@ alloc_from_freelist(struct drm_buddy *mm,
>> break;
>> }
>> }
>> - }
>> - if (!block)
>> - return ERR_PTR(-ENOSPC);
>> + if (!block)
>> + return ERR_PTR(-ENOSPC);
>> + }
>> BUG_ON(!drm_buddy_block_is_free(block));
>> @@ -524,6 +628,8 @@ 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);
>> + if (drm_buddy_block_is_clear(block))
>> + mm->clear_avail -= drm_buddy_block_size(mm, block);
>> list_add_tail(&block->link, &allocated);
>> continue;
>> }
>> @@ -558,7 +664,7 @@ static int __alloc_range(struct drm_buddy *mm,
>> list_splice_tail(&allocated, blocks);
>> *total_allocated_on_err = total_allocated;
>> } else {
>> - drm_buddy_free_list(mm, &allocated);
>> + drm_buddy_free_list(mm, &allocated, 0);
>> }
>> return err;
>> @@ -624,11 +730,11 @@ static int __alloc_contig_try_harder(struct
>> drm_buddy *mm,
>> list_splice(&blocks_lhs, blocks);
>> return 0;
>> } else if (err != -ENOSPC) {
>> - drm_buddy_free_list(mm, blocks);
>> + drm_buddy_free_list(mm, blocks, 0);
>> return err;
>> }
>> /* Free blocks for the next iteration */
>> - drm_buddy_free_list(mm, blocks);
>> + drm_buddy_free_list(mm, blocks, 0);
>> }
>> return -ENOSPC;
>> @@ -684,6 +790,8 @@ int drm_buddy_block_trim(struct drm_buddy *mm,
>> list_del(&block->link);
>> mark_free(mm, block);
>> mm->avail += drm_buddy_block_size(mm, block);
>> + if (drm_buddy_block_is_clear(block))
>> + mm->clear_avail += drm_buddy_block_size(mm, block);
>> /* Prevent recursively freeing this node */
>> parent = block->parent;
>> @@ -695,6 +803,8 @@ int drm_buddy_block_trim(struct drm_buddy *mm,
>> if (err) {
>> mark_allocated(block);
>> mm->avail -= drm_buddy_block_size(mm, block);
>> + if (drm_buddy_block_is_clear(block))
>> + mm->clear_avail -= drm_buddy_block_size(mm, block);
>> list_add(&block->link, blocks);
>> }
>> @@ -782,7 +892,8 @@ int drm_buddy_alloc_blocks(struct drm_buddy *mm,
>> do {
>> if (flags & DRM_BUDDY_RANGE_ALLOCATION)
>> /* Allocate traversing within the range */
>> - block = alloc_range_bias(mm, start, end, order);
>> + block = __drm_buddy_alloc_range_bias(mm, start, end,
>> + order, flags);
>> else
>> /* Allocate from freelist */
>> block = alloc_from_freelist(mm, order, flags);
>> @@ -808,6 +919,8 @@ int drm_buddy_alloc_blocks(struct drm_buddy *mm,
>> mark_allocated(block);
>> mm->avail -= drm_buddy_block_size(mm, block);
>> + if (drm_buddy_block_is_clear(block))
>> + mm->clear_avail -= drm_buddy_block_size(mm, block);
>> kmemleak_update_trace(block);
>> list_add_tail(&block->link, &allocated);
>> @@ -846,7 +959,7 @@ int drm_buddy_alloc_blocks(struct drm_buddy *mm,
>> return 0;
>> err_free:
>> - drm_buddy_free_list(mm, &allocated);
>> + drm_buddy_free_list(mm, &allocated, 0);
>> return err;
>> }
>> EXPORT_SYMBOL(drm_buddy_alloc_blocks);
>> @@ -879,8 +992,8 @@ void drm_buddy_print(struct drm_buddy *mm, struct
>> drm_printer *p)
>> {
>> int order;
>> - drm_printf(p, "chunk_size: %lluKiB, total: %lluMiB, free:
>> %lluMiB\n",
>> - mm->chunk_size >> 10, mm->size >> 20, mm->avail >> 20);
>> + drm_printf(p, "chunk_size: %lluKiB, total: %lluMiB, free:
>> %lluMiB, clear_free: %lluMiB\n",
>> + mm->chunk_size >> 10, mm->size >> 20, mm->avail >> 20,
>> mm->clear_avail >> 20);
>> for (order = mm->max_order; order >= 0; order--) {
>> struct drm_buddy_block *block;
>> diff --git a/drivers/gpu/drm/i915/i915_ttm_buddy_manager.c
>> b/drivers/gpu/drm/i915/i915_ttm_buddy_manager.c
>> index 0d735d5c2b35..942345548bc3 100644
>> --- a/drivers/gpu/drm/i915/i915_ttm_buddy_manager.c
>> +++ b/drivers/gpu/drm/i915/i915_ttm_buddy_manager.c
>> @@ -126,7 +126,7 @@ static int i915_ttm_buddy_man_alloc(struct
>> ttm_resource_manager *man,
>> return 0;
>> err_free_blocks:
>> - drm_buddy_free_list(mm, &bman_res->blocks);
>> + drm_buddy_free_list(mm, &bman_res->blocks, 0);
>> mutex_unlock(&bman->lock);
>> err_free_res:
>> ttm_resource_fini(man, &bman_res->base);
>> @@ -141,7 +141,7 @@ static void i915_ttm_buddy_man_free(struct
>> ttm_resource_manager *man,
>> struct i915_ttm_buddy_manager *bman = to_buddy_manager(man);
>> mutex_lock(&bman->lock);
>> - drm_buddy_free_list(&bman->mm, &bman_res->blocks);
>> + drm_buddy_free_list(&bman->mm, &bman_res->blocks, 0);
>> bman->visible_avail += bman_res->used_visible_size;
>> mutex_unlock(&bman->lock);
>> @@ -345,7 +345,7 @@ int i915_ttm_buddy_man_fini(struct ttm_device
>> *bdev, unsigned int type)
>> ttm_set_driver_manager(bdev, type, NULL);
>> mutex_lock(&bman->lock);
>> - drm_buddy_free_list(mm, &bman->reserved);
>> + drm_buddy_free_list(mm, &bman->reserved, 0);
>> drm_buddy_fini(mm);
>> bman->visible_avail += bman->visible_reserved;
>> WARN_ON_ONCE(bman->visible_avail != bman->visible_size);
>> diff --git a/drivers/gpu/drm/tests/drm_buddy_test.c
>> b/drivers/gpu/drm/tests/drm_buddy_test.c
>> index ea2af6bd9abe..e0860fce9ebd 100644
>> --- a/drivers/gpu/drm/tests/drm_buddy_test.c
>> +++ b/drivers/gpu/drm/tests/drm_buddy_test.c
>> @@ -83,7 +83,7 @@ static void
>> drm_test_buddy_alloc_pathological(struct kunit *test)
>> top, max_order);
>> }
>> - drm_buddy_free_list(&mm, &holes);
>> + drm_buddy_free_list(&mm, &holes, 0);
>> /* Nothing larger than blocks of chunk_size now available */
>> for (order = 1; order <= max_order; order++) {
>> @@ -95,7 +95,7 @@ static void
>> drm_test_buddy_alloc_pathological(struct kunit *test)
>> }
>> list_splice_tail(&holes, &blocks);
>> - drm_buddy_free_list(&mm, &blocks);
>> + drm_buddy_free_list(&mm, &blocks, 0);
>> drm_buddy_fini(&mm);
>> }
>> @@ -190,7 +190,7 @@ static void
>> drm_test_buddy_alloc_pessimistic(struct kunit *test)
>> list_del(&block->link);
>> drm_buddy_free_block(&mm, block);
>> - drm_buddy_free_list(&mm, &blocks);
>> + drm_buddy_free_list(&mm, &blocks, 0);
>> drm_buddy_fini(&mm);
>> }
>> @@ -236,7 +236,7 @@ static void
>> drm_test_buddy_alloc_optimistic(struct kunit *test)
>> size, size, &tmp, flags),
>> "buddy_alloc unexpectedly succeeded, it
>> should be full!");
>> - drm_buddy_free_list(&mm, &blocks);
>> + drm_buddy_free_list(&mm, &blocks, 0);
>> drm_buddy_fini(&mm);
>> }
>> @@ -271,7 +271,7 @@ static void drm_test_buddy_alloc_limit(struct
>> kunit *test)
>> drm_buddy_block_size(&mm, block),
>> BIT_ULL(mm.max_order) * PAGE_SIZE);
>> - drm_buddy_free_list(&mm, &allocated);
>> + drm_buddy_free_list(&mm, &allocated, 0);
>> drm_buddy_fini(&mm);
>> }
>> diff --git a/include/drm/drm_buddy.h b/include/drm/drm_buddy.h
>> index a5b39fc01003..f7311b59f2b0 100644
>> --- a/include/drm/drm_buddy.h
>> +++ b/include/drm/drm_buddy.h
>> @@ -6,6 +6,7 @@
>> #ifndef __DRM_BUDDY_H__
>> #define __DRM_BUDDY_H__
>> +#include <linux/bitfield.h>
>> #include <linux/bitops.h>
>> #include <linux/list.h>
>> #include <linux/slab.h>
>> @@ -25,15 +26,19 @@
>> #define DRM_BUDDY_RANGE_ALLOCATION BIT(0)
>> #define DRM_BUDDY_TOPDOWN_ALLOCATION BIT(1)
>> #define DRM_BUDDY_CONTIGUOUS_ALLOCATION BIT(2)
>> +#define DRM_BUDDY_CLEAR_ALLOCATION BIT(3)
>> +#define DRM_BUDDY_CLEARED BIT(4)
>> struct drm_buddy_block {
>> #define DRM_BUDDY_HEADER_OFFSET GENMASK_ULL(63, 12)
>> #define DRM_BUDDY_HEADER_STATE GENMASK_ULL(11, 10)
>> +#define DRM_BUDDY_HEADER_CLEAR GENMASK_ULL(9, 9)
>> +
>> #define DRM_BUDDY_ALLOCATED (1 << 10)
>> #define DRM_BUDDY_FREE (2 << 10)
>> #define DRM_BUDDY_SPLIT (3 << 10)
>> /* Free to be used, if needed in the future */
>> -#define DRM_BUDDY_HEADER_UNUSED GENMASK_ULL(9, 6)
>> +#define DRM_BUDDY_HEADER_UNUSED GENMASK_ULL(8, 6)
>> #define DRM_BUDDY_HEADER_ORDER GENMASK_ULL(5, 0)
>> u64 header;
>> @@ -86,6 +91,7 @@ struct drm_buddy {
>> u64 chunk_size;
>> u64 size;
>> u64 avail;
>> + u64 clear_avail;
>> };
>> static inline u64
>> @@ -112,6 +118,12 @@ drm_buddy_block_is_allocated(struct
>> drm_buddy_block *block)
>> return drm_buddy_block_state(block) == DRM_BUDDY_ALLOCATED;
>> }
>> +static inline bool
>> +drm_buddy_block_is_clear(struct drm_buddy_block *block)
>> +{
>> + return block->header & DRM_BUDDY_HEADER_CLEAR;
>> +}
>> +
>> static inline bool
>> drm_buddy_block_is_free(struct drm_buddy_block *block)
>> {
>> @@ -150,7 +162,9 @@ int drm_buddy_block_trim(struct drm_buddy *mm,
>> void drm_buddy_free_block(struct drm_buddy *mm, struct
>> drm_buddy_block *block);
>> -void drm_buddy_free_list(struct drm_buddy *mm, struct list_head
>> *objects);
>> +void drm_buddy_free_list(struct drm_buddy *mm,
>> + struct list_head *objects,
>> + unsigned long flags);
>> void drm_buddy_print(struct drm_buddy *mm, struct drm_printer *p);
>> void drm_buddy_block_print(struct drm_buddy *mm,
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