[PATCH vkd3d 2/2] vkd3d: Optimise the GPU VA allocator.
Henri Verbeet
hverbeet at codeweavers.com
Thu Oct 24 09:33:41 CDT 2019
From: Hans-Kristian Arntzen <post at arntzen-software.no>
The GPU VA allocator was allocating memory in a way where dereferencing
GPU VA required a lock + bsearch() to find the right VA range.
Rather than going this route, we turn the common case into O(1) and
lock-free by creating a slab allocator which allows us to lookup a
pointer directly from a GPU VA with (VA - Base) / PageSize.
The number of allocations in the fast path must be limited since we
cannot trivially grow the allocator while remaining lock-free for
dereferences.
Signed-off-by: Hans-Kristian Arntzen <post at arntzen-software.no>
Signed-off-by: Henri Verbeet <hverbeet at codeweavers.com>
---
This supersedes patch 171219.
libs/vkd3d/device.c | 226 +++++++++++++++++++++++++++++++++++++--------
libs/vkd3d/vkd3d_private.h | 28 ++++--
2 files changed, 204 insertions(+), 50 deletions(-)
diff --git a/libs/vkd3d/device.c b/libs/vkd3d/device.c
index 2dee5e3..4d6f7c9 100644
--- a/libs/vkd3d/device.c
+++ b/libs/vkd3d/device.c
@@ -1822,11 +1822,70 @@ static void d3d12_device_destroy_pipeline_cache(struct d3d12_device *device)
pthread_mutex_destroy(&device->mutex);
}
-D3D12_GPU_VIRTUAL_ADDRESS vkd3d_gpu_va_allocator_allocate(struct vkd3d_gpu_va_allocator *allocator,
- size_t alignment, size_t size, void *ptr)
+#define VKD3D_VA_FALLBACK_BASE 0x8000000000000000ull
+#define VKD3D_VA_SLAB_BASE 0x0000001000000000ull
+#define VKD3D_VA_SLAB_SIZE_SHIFT 32
+#define VKD3D_VA_SLAB_SIZE (1ull << VKD3D_VA_SLAB_SIZE_SHIFT)
+#define VKD3D_VA_SLAB_COUNT (64 * 1024)
+
+static D3D12_GPU_VIRTUAL_ADDRESS vkd3d_gpu_va_allocator_allocate_slab(struct vkd3d_gpu_va_allocator *allocator,
+ size_t aligned_size, void *ptr)
+{
+ struct vkd3d_gpu_va_slab *slab;
+ D3D12_GPU_VIRTUAL_ADDRESS address;
+ unsigned slab_idx;
+
+ slab = allocator->free_slab;
+ allocator->free_slab = slab->ptr;
+ slab->size = aligned_size;
+ slab->ptr = ptr;
+
+ /* It is critical that the multiplication happens in 64-bit to not
+ * overflow. */
+ slab_idx = slab - allocator->slabs;
+ address = VKD3D_VA_SLAB_BASE + slab_idx * VKD3D_VA_SLAB_SIZE;
+
+ TRACE("Allocated address %#"PRIx64", slab %u, size %zu.\n", address, slab_idx, aligned_size);
+
+ return address;
+}
+
+static D3D12_GPU_VIRTUAL_ADDRESS vkd3d_gpu_va_allocator_allocate_fallback(struct vkd3d_gpu_va_allocator *allocator,
+ size_t alignment, size_t aligned_size, void *ptr)
{
struct vkd3d_gpu_va_allocation *allocation;
D3D12_GPU_VIRTUAL_ADDRESS base, ceiling;
+
+ base = allocator->fallback_floor;
+ ceiling = ~(D3D12_GPU_VIRTUAL_ADDRESS)0;
+ ceiling -= alignment - 1;
+ if (aligned_size > ceiling || ceiling - aligned_size < base)
+ return 0;
+
+ base = (base + (alignment - 1)) & ~((D3D12_GPU_VIRTUAL_ADDRESS)alignment - 1);
+
+ if (!vkd3d_array_reserve((void **)&allocator->fallback_allocations, &allocator->fallback_allocations_size,
+ allocator->fallback_allocation_count + 1, sizeof(*allocator->fallback_allocations)))
+ return 0;
+
+ allocation = &allocator->fallback_allocations[allocator->fallback_allocation_count++];
+ allocation->base = base;
+ allocation->size = aligned_size;
+ allocation->ptr = ptr;
+
+ /* This pointer is bumped and never lowered on a free. However, this will
+ * only fail once we have exhausted 63 bits of address space. */
+ allocator->fallback_floor = base + aligned_size;
+
+ TRACE("Allocated address %#"PRIx64", size %zu.\n", base, aligned_size);
+
+ return base;
+}
+
+D3D12_GPU_VIRTUAL_ADDRESS vkd3d_gpu_va_allocator_allocate(struct vkd3d_gpu_va_allocator *allocator,
+ size_t alignment, size_t size, void *ptr)
+{
+ D3D12_GPU_VIRTUAL_ADDRESS address;
int rc;
if (size > ~(size_t)0 - (alignment - 1))
@@ -1839,34 +1898,41 @@ D3D12_GPU_VIRTUAL_ADDRESS vkd3d_gpu_va_allocator_allocate(struct vkd3d_gpu_va_al
return 0;
}
- base = allocator->floor;
- ceiling = ~(D3D12_GPU_VIRTUAL_ADDRESS)0;
- ceiling -= alignment - 1;
- if (size > ceiling || ceiling - size < base)
- {
- pthread_mutex_unlock(&allocator->mutex);
- return 0;
- }
+ if (size <= VKD3D_VA_SLAB_SIZE && allocator->free_slab)
+ address = vkd3d_gpu_va_allocator_allocate_slab(allocator, size, ptr);
+ else
+ address = vkd3d_gpu_va_allocator_allocate_fallback(allocator, alignment, size, ptr);
- base = (base + (alignment - 1)) & ~((D3D12_GPU_VIRTUAL_ADDRESS)alignment - 1);
+ pthread_mutex_unlock(&allocator->mutex);
- if (!vkd3d_array_reserve((void **)&allocator->allocations, &allocator->allocations_size,
- allocator->allocation_count + 1, sizeof(*allocator->allocations)))
- {
- pthread_mutex_unlock(&allocator->mutex);
- return 0;
- }
+ return address;
+}
- allocation = &allocator->allocations[allocator->allocation_count++];
- allocation->base = base;
- allocation->size = size;
- allocation->ptr = ptr;
+static void *vkd3d_gpu_va_allocator_dereference_slab(struct vkd3d_gpu_va_allocator *allocator,
+ D3D12_GPU_VIRTUAL_ADDRESS address)
+{
+ const struct vkd3d_gpu_va_slab *slab;
+ D3D12_GPU_VIRTUAL_ADDRESS base_offset;
+ unsigned int slab_idx;
- allocator->floor = base + size;
+ base_offset = address - VKD3D_VA_SLAB_BASE;
+ slab_idx = base_offset >> VKD3D_VA_SLAB_SIZE_SHIFT;
- pthread_mutex_unlock(&allocator->mutex);
+ if (slab_idx >= VKD3D_VA_SLAB_COUNT)
+ {
+ ERR("Invalid slab index %u for address %#"PRIx64".\n", slab_idx, address);
+ return NULL;
+ }
- return allocation->base;
+ slab = &allocator->slabs[slab_idx];
+ base_offset -= slab_idx * VKD3D_VA_SLAB_SIZE;
+ if (base_offset >= slab->size)
+ {
+ ERR("Address %#"PRIx64" is %#"PRIx64" bytes into slab %u of size %zu.\n",
+ address, base_offset, slab_idx, slab->size);
+ return NULL;
+ }
+ return slab->ptr;
}
static int vkd3d_gpu_va_allocation_compare(const void *k, const void *e)
@@ -1881,30 +1947,94 @@ static int vkd3d_gpu_va_allocation_compare(const void *k, const void *e)
return 0;
}
-void *vkd3d_gpu_va_allocator_dereference(struct vkd3d_gpu_va_allocator *allocator,
+static void *vkd3d_gpu_va_allocator_dereference_fallback(struct vkd3d_gpu_va_allocator *allocator,
D3D12_GPU_VIRTUAL_ADDRESS address)
{
struct vkd3d_gpu_va_allocation *allocation;
+
+ allocation = bsearch(&address, allocator->fallback_allocations, allocator->fallback_allocation_count,
+ sizeof(*allocation), vkd3d_gpu_va_allocation_compare);
+
+ return allocation ? allocation->ptr : NULL;
+}
+
+void *vkd3d_gpu_va_allocator_dereference(struct vkd3d_gpu_va_allocator *allocator,
+ D3D12_GPU_VIRTUAL_ADDRESS address)
+{
+ void *ret;
int rc;
+ /* If we land in the non-fallback region, dereferencing VA is lock-less.
+ * The base pointer is immutable, and the only way we can have a data race
+ * is if some other thread is poking into the
+ * slab_mem_allocation[base_index] block. This can only happen if someone
+ * is trying to free the entry while we're dereferencing it, which would
+ * be a serious application bug. */
+ if (address < VKD3D_VA_FALLBACK_BASE)
+ return vkd3d_gpu_va_allocator_dereference_slab(allocator, address);
+
+ /* Slow fallback. */
if ((rc = pthread_mutex_lock(&allocator->mutex)))
{
ERR("Failed to lock mutex, error %d.\n", rc);
return NULL;
}
- allocation = bsearch(&address, allocator->allocations, allocator->allocation_count,
- sizeof(*allocation), vkd3d_gpu_va_allocation_compare);
+ ret = vkd3d_gpu_va_allocator_dereference_fallback(allocator, address);
pthread_mutex_unlock(&allocator->mutex);
- return allocation ? allocation->ptr : NULL;
+ return ret;
}
-void vkd3d_gpu_va_allocator_free(struct vkd3d_gpu_va_allocator *allocator, D3D12_GPU_VIRTUAL_ADDRESS address)
+static void vkd3d_gpu_va_allocator_free_slab(struct vkd3d_gpu_va_allocator *allocator,
+ D3D12_GPU_VIRTUAL_ADDRESS address)
+{
+ D3D12_GPU_VIRTUAL_ADDRESS base_offset;
+ struct vkd3d_gpu_va_slab *slab;
+ unsigned int slab_idx;
+
+ base_offset = address - VKD3D_VA_SLAB_BASE;
+ slab_idx = base_offset >> VKD3D_VA_SLAB_SIZE_SHIFT;
+
+ if (slab_idx >= VKD3D_VA_SLAB_COUNT)
+ {
+ ERR("Invalid slab index %u for address %#"PRIx64".\n", slab_idx, address);
+ return;
+ }
+
+ TRACE("Freeing address %#"PRIx64", slab %u.\n", address, slab_idx);
+
+ slab = &allocator->slabs[slab_idx];
+ slab->size = 0;
+ slab->ptr = allocator->free_slab;
+ allocator->free_slab = slab;
+}
+
+static void vkd3d_gpu_va_allocator_free_fallback(struct vkd3d_gpu_va_allocator *allocator,
+ D3D12_GPU_VIRTUAL_ADDRESS address)
{
struct vkd3d_gpu_va_allocation *allocation;
unsigned int index;
+
+ allocation = bsearch(&address, allocator->fallback_allocations, allocator->fallback_allocation_count,
+ sizeof(*allocation), vkd3d_gpu_va_allocation_compare);
+
+ if (!allocation || allocation->base != address)
+ {
+ ERR("Address %#"PRIx64" does not match any allocation.\n", address);
+ return;
+ }
+
+ index = allocation - allocator->fallback_allocations;
+ --allocator->fallback_allocation_count;
+ if (index != allocator->fallback_allocation_count)
+ memmove(&allocator->fallback_allocations[index], &allocator->fallback_allocations[index + 1],
+ (allocator->fallback_allocation_count - index) * sizeof(*allocation));
+}
+
+void vkd3d_gpu_va_allocator_free(struct vkd3d_gpu_va_allocator *allocator, D3D12_GPU_VIRTUAL_ADDRESS address)
+{
int rc;
if ((rc = pthread_mutex_lock(&allocator->mutex)))
@@ -1913,32 +2043,45 @@ void vkd3d_gpu_va_allocator_free(struct vkd3d_gpu_va_allocator *allocator, D3D12
return;
}
- allocation = bsearch(&address, allocator->allocations, allocator->allocation_count,
- sizeof(*allocation), vkd3d_gpu_va_allocation_compare);
- if (allocation && allocation->base == address)
+ if (address < VKD3D_VA_FALLBACK_BASE)
{
- index = allocation - allocator->allocations;
- --allocator->allocation_count;
- if (index != allocator->allocation_count)
- {
- memmove(&allocator->allocations[index], &allocator->allocations[index + 1],
- (allocator->allocation_count - index) * sizeof(*allocation));
- }
+ vkd3d_gpu_va_allocator_free_slab(allocator, address);
+ pthread_mutex_unlock(&allocator->mutex);
+ return;
}
+ vkd3d_gpu_va_allocator_free_fallback(allocator, address);
+
pthread_mutex_unlock(&allocator->mutex);
}
static bool vkd3d_gpu_va_allocator_init(struct vkd3d_gpu_va_allocator *allocator)
{
+ unsigned int i;
int rc;
memset(allocator, 0, sizeof(*allocator));
- allocator->floor = 0x1000;
+ allocator->fallback_floor = VKD3D_VA_FALLBACK_BASE;
+
+ /* To remain lock-less, we cannot grow the slabs array after the fact. If
+ * we commit to a maximum number of allocations here, we can dereference
+ * without taking a lock as the base pointer never changes. We would be
+ * able to grow more seamlessly using an array of pointers, but that would
+ * make dereferencing slightly less efficient. */
+ if (!(allocator->slabs = vkd3d_calloc(VKD3D_VA_SLAB_COUNT, sizeof(*allocator->slabs))))
+ return false;
+
+ /* Mark all slabs as free. */
+ allocator->free_slab = &allocator->slabs[0];
+ for (i = 0; i < VKD3D_VA_SLAB_COUNT - 1; ++i)
+ {
+ allocator->slabs[i].ptr = &allocator->slabs[i + 1];
+ }
if ((rc = pthread_mutex_init(&allocator->mutex, NULL)))
{
ERR("Failed to initialize mutex, error %d.\n", rc);
+ vkd3d_free(allocator->slabs);
return false;
}
@@ -1954,7 +2097,8 @@ static void vkd3d_gpu_va_allocator_cleanup(struct vkd3d_gpu_va_allocator *alloca
ERR("Failed to lock mutex, error %d.\n", rc);
return;
}
- vkd3d_free(allocator->allocations);
+ vkd3d_free(allocator->slabs);
+ vkd3d_free(allocator->fallback_allocations);
pthread_mutex_unlock(&allocator->mutex);
pthread_mutex_destroy(&allocator->mutex);
}
diff --git a/libs/vkd3d/vkd3d_private.h b/libs/vkd3d/vkd3d_private.h
index 520dab1..1cb40f2 100644
--- a/libs/vkd3d/vkd3d_private.h
+++ b/libs/vkd3d/vkd3d_private.h
@@ -202,20 +202,30 @@ HRESULT vkd3d_fence_worker_start(struct vkd3d_fence_worker *worker,
HRESULT vkd3d_fence_worker_stop(struct vkd3d_fence_worker *worker,
struct d3d12_device *device) DECLSPEC_HIDDEN;
+struct vkd3d_gpu_va_allocation
+{
+ D3D12_GPU_VIRTUAL_ADDRESS base;
+ SIZE_T size;
+ void *ptr;
+};
+
+struct vkd3d_gpu_va_slab
+{
+ SIZE_T size;
+ void *ptr;
+};
+
struct vkd3d_gpu_va_allocator
{
pthread_mutex_t mutex;
- D3D12_GPU_VIRTUAL_ADDRESS floor;
+ D3D12_GPU_VIRTUAL_ADDRESS fallback_floor;
+ struct vkd3d_gpu_va_allocation *fallback_allocations;
+ size_t fallback_allocations_size;
+ size_t fallback_allocation_count;
- struct vkd3d_gpu_va_allocation
- {
- D3D12_GPU_VIRTUAL_ADDRESS base;
- SIZE_T size;
- void *ptr;
- } *allocations;
- size_t allocations_size;
- size_t allocation_count;
+ struct vkd3d_gpu_va_slab *slabs;
+ struct vkd3d_gpu_va_slab *free_slab;
};
D3D12_GPU_VIRTUAL_ADDRESS vkd3d_gpu_va_allocator_allocate(struct vkd3d_gpu_va_allocator *allocator,
--
2.11.0
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