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Merged
merged 2 commits into from
Sep 21, 2025
Merged

vulkan: optimize UMA buffer operations and fix driver hangs #16059

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c634057
vulkan: optimize UMA buffer operations and fix driver hangs
giuseppe Sep 17, 2025
87d3cd0
vulkan: implement deferred_memset on UMA
giuseppe Sep 18, 2025
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39 changes: 39 additions & 0 deletions ggml/src/ggml-vulkan/ggml-vulkan.cpp
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Original file line number Diff line number Diff line change
Expand Up @@ -1185,6 +1185,14 @@ struct vk_staging_memcpy {
size_t n;
};

struct vk_staging_memset {
vk_staging_memset(void * _dst, uint32_t _val, size_t _n) : dst(_dst), val(_val), n(_n) {}

void * dst;
uint32_t val;
size_t n;
};

struct vk_context_struct {
vk_submission * s;
std::vector<vk_sequence> seqs;
Expand All @@ -1193,6 +1201,7 @@ struct vk_context_struct {

std::vector<vk_staging_memcpy> in_memcpys;
std::vector<vk_staging_memcpy> out_memcpys;
std::vector<vk_staging_memset> memsets;

vk_command_pool * p {};
};
Expand Down Expand Up @@ -5194,6 +5203,14 @@ static void deferred_memcpy(void * dst, const void * src, size_t size, std::vect
}
}

static void deferred_memset(void * dst, uint32_t val, size_t size, std::vector<vk_staging_memset>* memsets = nullptr) {
if (memsets == nullptr) {
memset(dst, val, size);
} else {
memsets->emplace_back(dst, val, size);
}
}

static void ggml_vk_ensure_sync_staging_buffer(vk_device& device, size_t size) {
if (device->sync_staging == nullptr || device->sync_staging->size < size) {
VK_LOG_MEMORY("ggml_vk_ensure_sync_staging_buffer(" << size << ")");
Expand Down Expand Up @@ -5389,6 +5406,10 @@ static void ggml_vk_buffer_write_2d(vk_buffer& dst, size_t offset, const void *
memcpy(cpy.dst, cpy.src, cpy.n);
}

for (auto& mset : subctx->memsets) {
memset(mset.dst, mset.val, mset.n);
}

ggml_vk_submit(subctx, dst->device->fence);
VK_CHECK(dst->device->device.waitForFences({ dst->device->fence }, true, UINT64_MAX), "vk_buffer_write_2d waitForFences");
dst->device->device.resetFences({ dst->device->fence });
Expand Down Expand Up @@ -5528,12 +5549,25 @@ static void ggml_vk_buffer_copy(vk_buffer& dst, size_t dst_offset, vk_buffer& sr
static void ggml_vk_buffer_memset_async(vk_context& ctx, vk_buffer& dst, size_t offset, uint32_t c, size_t size) {
VK_LOG_DEBUG("ggml_vk_buffer_memset_async(" << offset << ", " << c << ", " << size << ")");

if (dst->memory_property_flags & vk::MemoryPropertyFlagBits::eHostVisible &&
dst->device->uma) {
deferred_memset((uint8_t*)dst->ptr + offset, c, size, &ctx->memsets);
return;
}

// Fall back to GPU fillBuffer for non-UMA or non-host-visible buffers
ctx->s->buffer.fillBuffer(dst->buffer, offset, size, c);
}

static void ggml_vk_buffer_memset(vk_buffer& dst, size_t offset, uint32_t c, size_t size) {
VK_LOG_DEBUG("ggml_vk_buffer_memset(" << offset << ", " << c << ", " << size << ")");

if (dst->memory_property_flags & vk::MemoryPropertyFlagBits::eHostVisible &&
dst->device->uma) {
memset((uint8_t*)dst->ptr + offset, c, size);
return;
}

std::lock_guard<std::recursive_mutex> guard(dst->device->mutex);
vk_context subctx = ggml_vk_create_temporary_context(dst->device->transfer_queue.cmd_pool);
ggml_vk_ctx_begin(dst->device, subctx);
Expand Down Expand Up @@ -11168,6 +11202,10 @@ static bool ggml_vk_compute_forward(ggml_backend_vk_context * ctx, ggml_cgraph *
memcpy(cpy.dst, cpy.src, cpy.n);
}

for (auto& mset : subctx->memsets) {
memset(mset.dst, mset.val, mset.n);
}

if (almost_ready && !ctx->almost_ready_fence_pending && !use_fence) {
ggml_vk_submit(subctx, ctx->almost_ready_fence);
ctx->almost_ready_fence_pending = true;
Expand All @@ -11190,6 +11228,7 @@ static bool ggml_vk_compute_forward(ggml_backend_vk_context * ctx, ggml_cgraph *
}
subctx->in_memcpys.clear();
subctx->out_memcpys.clear();
subctx->memsets.clear();
}

return true;
Expand Down
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