Reviewed-by: Jordan Justen <jordan.l.jus...@intel.com>
On 2018-05-27 21:35:40, Kenneth Graunke wrote:
> This introduces a new fast virtual memory allocator integrated with our
> BO cache bucketing. For larger objects, it falls back to the simple
> free-list allocator (util_vma).
>
> This puts the allocators in place but doesn't enable softpin yet.
>
> v2:
> (feedback from Chris Wilson)
> - Check (bo->kflags & EXEC_OBJECT_PINNED) instead of a global flag
> - Avoid vma_free(0ull) on the err_free path.
> - Only enable if the kernel says we have full PPGTT support
> - Make bucketing allocators more resistant to failing to grow arrays
> (feedback from Scott Phillips)
> - Don't use node after popping it from the list.
> - Avoid undefined behavior in canonicalization by reusing new helper
> - Comment updates
> (feedback from myself)
> - Avoid __vma_alloc vs. vma_alloc by making a zero_high_bits helper
> to return a non-canonical address with the high bits zeroed.
> ---
> src/mesa/drivers/dri/i965/brw_bufmgr.c | 291 ++++++++++++++++++++++++-
> src/mesa/drivers/dri/i965/brw_bufmgr.h | 2 +
> 2 files changed, 292 insertions(+), 1 deletion(-)
>
> I plan to land this series this week, barring any major objections.
> Scott reviewed it all (from my v1.9 branch), but I wasn't positive
> whether some of his reviews still applied...so I figured I'd play it
> safe and send it out one more time.
>
> diff --git a/src/mesa/drivers/dri/i965/brw_bufmgr.c
> b/src/mesa/drivers/dri/i965/brw_bufmgr.c
> index 66828f319be..13d32255715 100644
> --- a/src/mesa/drivers/dri/i965/brw_bufmgr.c
> +++ b/src/mesa/drivers/dri/i965/brw_bufmgr.c
> @@ -54,12 +54,15 @@
> #endif
> #include "common/gen_clflush.h"
> #include "common/gen_debug.h"
> +#include "common/gen_gem.h"
> #include "dev/gen_device_info.h"
> #include "libdrm_macros.h"
> #include "main/macros.h"
> #include "util/macros.h"
> #include "util/hash_table.h"
> #include "util/list.h"
> +#include "util/u_dynarray.h"
> +#include "util/vma.h"
> #include "brw_bufmgr.h"
> #include "brw_context.h"
> #include "string.h"
> @@ -98,9 +101,41 @@ atomic_add_unless(int *v, int add, int unless)
> return c == unless;
> }
>
> +/**
> + * i965 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[BRW_MEMZONE_COUNT];
> };
>
> struct brw_bufmgr {
> @@ -116,6 +151,8 @@ struct brw_bufmgr {
> struct hash_table *name_table;
> struct hash_table *handle_table;
>
> + struct util_vma_heap vma_allocator[BRW_MEMZONE_COUNT];
> +
> bool has_llc:1;
> bool has_mmap_wc:1;
> bool bo_reuse:1;
> @@ -128,6 +165,17 @@ static int bo_set_tiling_internal(struct brw_bo *bo,
> uint32_t tiling_mode,
>
> static void bo_free(struct brw_bo *bo);
>
> +static uint64_t
> +zero_high_bits(uint64_t addr)
> +{
> + /* Un-canonicalize the address, zeroing out the high bits. */
> + return addr & ((1ull << 48) - 1);
> +}
> +
> +static uint64_t vma_alloc(struct brw_bufmgr *bufmgr,
> + enum brw_memory_zone memzone,
> + uint64_t size, uint64_t alignment);
> +
> static uint32_t
> key_hash_uint(const void *key)
> {
> @@ -222,6 +270,187 @@ bucket_for_size(struct brw_bufmgr *bufmgr, uint64_t
> size)
> &bufmgr->cache_bucket[index] : NULL;
> }
>
> +static enum brw_memory_zone
> +memzone_for_address(uint64_t address)
> +{
> + const uint64_t _4GB = 1ull << 32;
> +
> + if (address >= _4GB)
> + return BRW_MEMZONE_OTHER;
> +
> + return BRW_MEMZONE_LOW_4G;
> +}
> +
> +static uint64_t
> +bucket_vma_alloc(struct brw_bufmgr *bufmgr,
> + struct bo_cache_bucket *bucket,
> + enum brw_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.
> + */
> + 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 = zero_high_bits(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 brw_memory_zone memzone = 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 brw_bufmgr *bufmgr, 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.
> + *
> + * This uses either the bucket allocator for the given size, or the large
> + * object allocator (util_vma).
> + */
> +static uint64_t
> +vma_alloc(struct brw_bufmgr *bufmgr,
> + enum brw_memory_zone memzone,
> + uint64_t size,
> + uint64_t alignment)
> +{
> + /* Without softpin support, we let the kernel assign addresses. */
> + assert(brw_using_softpin(bufmgr));
> +
> + struct bo_cache_bucket *bucket = get_bucket_allocator(bufmgr, 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);
> + }
> +
> + assert((addr >> 48ull) == 0);
> + assert((addr % alignment) == 0);
> +
> + return gen_canonical_address(addr);
> +}
> +
> +/**
> + * Free a virtual memory area, allowing the address to be reused.
> + */
> +static void
> +vma_free(struct brw_bufmgr *bufmgr,
> + uint64_t address,
> + uint64_t size)
> +{
> + assert(brw_using_softpin(bufmgr));
> +
> + /* Un-canonicalize the address. */
> + address = zero_high_bits(address);
> +
> + if (address == 0ull)
> + return;
> +
> + struct bo_cache_bucket *bucket = get_bucket_allocator(bufmgr, size);
> +
> + if (bucket) {
> + bucket_vma_free(bucket, address);
> + } else {
> + enum brw_memory_zone memzone = memzone_for_address(address);
> + util_vma_heap_free(&bufmgr->vma_allocator[memzone], address, size);
> + }
> +}
> +
> int
> brw_bo_busy(struct brw_bo *bo)
> {
> @@ -360,7 +589,16 @@ retry:
> }
> }
>
> - if (!alloc_from_cache) {
> + if (alloc_from_cache) {
> + /* If the cache BO isn't in the right memory zone, free the old
> + * memory and assign it a new address.
> + */
> + if ((bo->kflags & EXEC_OBJECT_PINNED) &&
> + memzone != memzone_for_address(bo->gtt_offset)) {
> + vma_free(bufmgr, bo->gtt_offset, bo->size);
> + bo->gtt_offset = 0ull;
> + }
> + } else {
> bo = calloc(1, sizeof(*bo));
> if (!bo)
> goto err;
> @@ -411,6 +649,13 @@ retry:
> bo->index = -1;
> bo->kflags = bufmgr->initial_kflags;
>
> + if ((bo->kflags & EXEC_OBJECT_PINNED) && bo->gtt_offset == 0ull) {
> + bo->gtt_offset = vma_alloc(bufmgr, memzone, bo->size, 1);
> +
> + if (bo->gtt_offset == 0ull)
> + goto err_free;
> + }
> +
> mtx_unlock(&bufmgr->lock);
>
> DBG("bo_create: buf %d (%s) %llub\n", bo->gem_handle, bo->name,
> @@ -545,6 +790,9 @@ brw_bo_gem_create_from_name(struct brw_bufmgr *bufmgr,
> bo->external = true;
> bo->kflags = bufmgr->initial_kflags;
>
> + if (bo->kflags & EXEC_OBJECT_PINNED)
> + bo->gtt_offset = vma_alloc(bufmgr, BRW_MEMZONE_OTHER, bo->size, 1);
> +
> _mesa_hash_table_insert(bufmgr->handle_table, &bo->gem_handle, bo);
> _mesa_hash_table_insert(bufmgr->name_table, &bo->global_name, bo);
>
> @@ -605,6 +853,10 @@ bo_free(struct brw_bo *bo)
> DBG("DRM_IOCTL_GEM_CLOSE %d failed (%s): %s\n",
> bo->gem_handle, bo->name, strerror(errno));
> }
> +
> + if (bo->kflags & EXEC_OBJECT_PINNED)
> + vma_free(bo->bufmgr, bo->gtt_offset, bo->size);
> +
> free(bo);
> }
>
> @@ -1063,11 +1315,22 @@ brw_bufmgr_destroy(struct brw_bufmgr *bufmgr)
>
> bo_free(bo);
> }
> +
> + if (brw_using_softpin(bufmgr)) {
> + for (int i = 0; i < BRW_MEMZONE_COUNT; i++)
> + util_dynarray_fini(&bucket->vma_list[i]);
> + }
> }
>
> _mesa_hash_table_destroy(bufmgr->name_table, NULL);
> _mesa_hash_table_destroy(bufmgr->handle_table, NULL);
>
> + if (brw_using_softpin(bufmgr)) {
> + for (int z = 0; z < BRW_MEMZONE_COUNT; z++) {
> + util_vma_heap_finish(&bufmgr->vma_allocator[z]);
> + }
> + }
> +
> free(bufmgr);
> }
>
> @@ -1165,6 +1428,11 @@ brw_bo_gem_create_from_prime_internal(struct
> brw_bufmgr *bufmgr, int prime_fd,
> bo->external = true;
> bo->kflags = bufmgr->initial_kflags;
>
> + if (bo->kflags & EXEC_OBJECT_PINNED) {
> + assert(bo->size > 0);
> + bo->gtt_offset = vma_alloc(bufmgr, BRW_MEMZONE_OTHER, bo->size, 1);
> + }
> +
> if (tiling_mode < 0) {
> struct drm_i915_gem_get_tiling get_tiling = { .handle = bo->gem_handle
> };
> if (drmIoctl(bufmgr->fd, DRM_IOCTL_I915_GEM_GET_TILING, &get_tiling))
> @@ -1291,6 +1559,10 @@ add_bucket(struct brw_bufmgr *bufmgr, int size)
> assert(i < ARRAY_SIZE(bufmgr->cache_bucket));
>
> list_inithead(&bufmgr->cache_bucket[i].head);
> + if (brw_using_softpin(bufmgr)) {
> + for (int z = 0; z < BRW_MEMZONE_COUNT; z++)
> + util_dynarray_init(&bufmgr->cache_bucket[i].vma_list[z], NULL);
> + }
> bufmgr->cache_bucket[i].size = size;
> bufmgr->num_buckets++;
>
> @@ -1408,6 +1680,12 @@ gem_context_getparam(int fd, uint32_t context,
> uint64_t param, uint64_t *value)
> return 0;
> }
>
> +bool
> +brw_using_softpin(struct brw_bufmgr *bufmgr)
> +{
> + return bufmgr->initial_kflags & EXEC_OBJECT_PINNED;
> +}
> +
> /**
> * Initializes the GEM buffer manager, which uses the kernel to allocate,
> map,
> * and manage map buffer objections.
> @@ -1450,6 +1728,17 @@ brw_bufmgr_init(struct gen_device_info *devinfo, int
> fd)
>
> if (devinfo->gen >= 8 && gtt_size > _4GB) {
> bufmgr->initial_kflags |= EXEC_OBJECT_SUPPORTS_48B_ADDRESS;
> +
> + /* Allocate VMA in userspace if we have softpin and full PPGTT. */
> + if (false && gem_param(fd, I915_PARAM_HAS_EXEC_SOFTPIN) > 0 &&
> + gem_param(fd, I915_PARAM_HAS_ALIASING_PPGTT) > 1) {
> + bufmgr->initial_kflags |= EXEC_OBJECT_PINNED;
> +
> + util_vma_heap_init(&bufmgr->vma_allocator[BRW_MEMZONE_LOW_4G],
> + 4096, _4GB);
> + util_vma_heap_init(&bufmgr->vma_allocator[BRW_MEMZONE_OTHER],
> + 1 * _4GB, gtt_size - 1 * _4GB);
> + }
> }
>
> init_cache_buckets(bufmgr);
> diff --git a/src/mesa/drivers/dri/i965/brw_bufmgr.h
> b/src/mesa/drivers/dri/i965/brw_bufmgr.h
> index 9ad129744b2..8cdf944e3da 100644
> --- a/src/mesa/drivers/dri/i965/brw_bufmgr.h
> +++ b/src/mesa/drivers/dri/i965/brw_bufmgr.h
> @@ -370,6 +370,8 @@ uint32_t brw_bo_export_gem_handle(struct brw_bo *bo);
> int brw_reg_read(struct brw_bufmgr *bufmgr, uint32_t offset,
> uint64_t *result);
>
> +bool brw_using_softpin(struct brw_bufmgr *bufmgr);
> +
> /** @{ */
>
> #if defined(__cplusplus)
> --
> 2.17.0
>
> _______________________________________________
> mesa-dev mailing list
> mesa-dev@lists.freedesktop.org
> https://lists.freedesktop.org/mailman/listinfo/mesa-dev
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