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iris: Delete bucketing allocators

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These add a lot of complexity, and I currently can't measure any
performance benefit from having them.  In the past, I seem to recall
seeing a benefit in drawoverhead scores, but currently it looks like
dropping them is either a wash or 1-2% faster.

Drop them to simplify allocations.
This commit is contained in:
Kenneth Graunke
2019-04-25 18:30:57 -07:00
parent bd4b18d255
commit 694d1a08d3
1 changed files with 3 additions and 167 deletions
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170
src/gallium/drivers/iris/iris_bufmgr.c
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@@ -132,41 +132,12 @@ memzone_name(enum iris_memory_zone memzone)
return names[memzone];
}
/**
* Iris fixed-size bucketing VMA allocator.
*
* The BO cache maintains "cache buckets" for buffers of various sizes.
* All buffers in a given bucket are identically sized - when allocating,
* we always round up to the bucket size. This means that virtually all
* allocations are fixed-size; only buffers which are too large to fit in
* a bucket can be variably-sized.
*
* We create an allocator for each bucket. Each contains a free-list, where
* each node contains a <starting address, 64-bit bitmap> pair. Each bit
* represents a bucket-sized block of memory. (At the first level, each
* bit corresponds to a page. For the second bucket, bits correspond to
* two pages, and so on.) 1 means a block is free, and 0 means it's in-use.
* The lowest bit in the bitmap is for the first block.
*
* This makes allocations cheap - any bit of any node will do. We can pick
* the head of the list and use ffs() to find a free block. If there are
* none, we allocate 64 blocks from a larger allocator - either a bigger
* bucketing allocator, or a fallback top-level allocator for large objects.
*/
struct vma_bucket_node {
uint64_t start_address;
uint64_t bitmap;
};
struct bo_cache_bucket {
/** List of cached BOs. */
struct list_head head;
/** Size of this bucket, in bytes. */
uint64_t size;
/** List of vma_bucket_nodes. */
struct util_dynarray vma_list[IRIS_MEMZONE_COUNT];
};
struct iris_bufmgr {
@@ -283,121 +254,6 @@ iris_memzone_for_address(uint64_t address)
return IRIS_MEMZONE_SHADER;
}
static uint64_t
bucket_vma_alloc(struct iris_bufmgr *bufmgr,
struct bo_cache_bucket *bucket,
enum iris_memory_zone memzone)
{
struct util_dynarray *vma_list = &bucket->vma_list[memzone];
struct vma_bucket_node *node;
if (vma_list->size == 0) {
/* This bucket allocator is out of space - allocate a new block of
* memory for 64 blocks from a larger allocator (either a larger
* bucket or util_vma).
*
* We align the address to the node size (64 blocks) so that
* bucket_vma_free can easily compute the starting address of this
* block by rounding any address we return down to the node size.
*
* Set the first bit used, and return the start address.
*/
const uint64_t node_size = 64ull * bucket->size;
node = util_dynarray_grow(vma_list, sizeof(struct vma_bucket_node));
if (unlikely(!node))
return 0ull;
uint64_t addr = vma_alloc(bufmgr, memzone, node_size, node_size);
node->start_address = gen_48b_address(addr);
node->bitmap = ~1ull;
return node->start_address;
}
/* Pick any bit from any node - they're all the right size and free. */
node = util_dynarray_top_ptr(vma_list, struct vma_bucket_node);
int bit = ffsll(node->bitmap) - 1;
assert(bit >= 0 && bit <= 63);
/* Reserve the memory by clearing the bit. */
assert((node->bitmap & (1ull << bit)) != 0ull);
node->bitmap &= ~(1ull << bit);
uint64_t addr = node->start_address + bit * bucket->size;
/* If this node is now completely full, remove it from the free list. */
if (node->bitmap == 0ull) {
(void) util_dynarray_pop(vma_list, struct vma_bucket_node);
}
return addr;
}
static void
bucket_vma_free(struct bo_cache_bucket *bucket, uint64_t address)
{
enum iris_memory_zone memzone = iris_memzone_for_address(address);
struct util_dynarray *vma_list = &bucket->vma_list[memzone];
const uint64_t node_bytes = 64ull * bucket->size;
struct vma_bucket_node *node = NULL;
/* bucket_vma_alloc allocates 64 blocks at a time, and aligns it to
* that 64 block size. So, we can round down to get the starting address.
*/
uint64_t start = (address / node_bytes) * node_bytes;
/* Dividing the offset from start by bucket size gives us the bit index. */
int bit = (address - start) / bucket->size;
assert(start + bit * bucket->size == address);
util_dynarray_foreach(vma_list, struct vma_bucket_node, cur) {
if (cur->start_address == start) {
node = cur;
break;
}
}
if (!node) {
/* No node - the whole group of 64 blocks must have been in-use. */
node = util_dynarray_grow(vma_list, sizeof(struct vma_bucket_node));
if (unlikely(!node))
return; /* bogus, leaks some GPU VMA, but nothing we can do... */
node->start_address = start;
node->bitmap = 0ull;
}
/* Set the bit to return the memory. */
assert((node->bitmap & (1ull << bit)) == 0ull);
node->bitmap |= 1ull << bit;
/* The block might be entirely free now, and if so, we could return it
* to the larger allocator. But we may as well hang on to it, in case
* we get more allocations at this block size.
*/
}
static struct bo_cache_bucket *
get_bucket_allocator(struct iris_bufmgr *bufmgr,
enum iris_memory_zone memzone,
uint64_t size)
{
/* Skip using the bucket allocator for very large sizes, as it allocates
* 64 of them and this can balloon rather quickly.
*/
if (size > 1024 * PAGE_SIZE)
return NULL;
struct bo_cache_bucket *bucket = bucket_for_size(bufmgr, size);
if (bucket && bucket->size == size)
return bucket;
return NULL;
}
/**
* Allocate a section of virtual memory for a buffer, assigning an address.
*
@@ -420,16 +276,8 @@ vma_alloc(struct iris_bufmgr *bufmgr,
if (memzone == IRIS_MEMZONE_BINDER)
return IRIS_MEMZONE_BINDER_START;
struct bo_cache_bucket *bucket =
get_bucket_allocator(bufmgr, memzone, size);
uint64_t addr;
if (bucket) {
addr = bucket_vma_alloc(bufmgr, bucket, memzone);
} else {
addr = util_vma_heap_alloc(&bufmgr->vma_allocator[memzone], size,
alignment);
}
uint64_t addr =
util_vma_heap_alloc(&bufmgr->vma_allocator[memzone], size, alignment);
assert((addr >> 48ull) == 0);
assert((addr % alignment) == 0);
@@ -457,14 +305,7 @@ vma_free(struct iris_bufmgr *bufmgr,
if (memzone == IRIS_MEMZONE_BINDER)
return;
struct bo_cache_bucket *bucket =
get_bucket_allocator(bufmgr, memzone, size);
if (bucket) {
bucket_vma_free(bucket, address);
} else {
util_vma_heap_free(&bufmgr->vma_allocator[memzone], address, size);
}
util_vma_heap_free(&bufmgr->vma_allocator[memzone], address, size);
}
int
@@ -1321,9 +1162,6 @@ iris_bufmgr_destroy(struct iris_bufmgr *bufmgr)
bo_free(bo);
}
for (int z = 0; z < IRIS_MEMZONE_COUNT; z++)
util_dynarray_fini(&bucket->vma_list[z]);
}
_mesa_hash_table_destroy(bufmgr->name_table, NULL);
@@ -1529,8 +1367,6 @@ add_bucket(struct iris_bufmgr *bufmgr, int size)
assert(i < ARRAY_SIZE(bufmgr->cache_bucket));
list_inithead(&bufmgr->cache_bucket[i].head);
for (int z = 0; z < IRIS_MEMZONE_COUNT; z++)
util_dynarray_init(&bufmgr->cache_bucket[i].vma_list[z], NULL);
bufmgr->cache_bucket[i].size = size;
bufmgr->num_buckets++;