Zero init. GPU workspace allocations by default (#1095)

* Added default param to GPUAllocator::reserve_workspace to request memory initialization for each invocation of the memory primitive.

* GPU workspace memory is zero initialized by default but can be turned off if desired.

src/ngraph/runtime/gpu/gpu_memory_manager.cpp

@@ -102,7 +102,7 @@ size_t runtime::gpu::GPUAllocator::reserve_argspace(const void* data, size_t siz
     return m_manager->m_primitive_emitter->insert(mem_primitive);
 }
 
-size_t runtime::gpu::GPUAllocator::reserve_workspace(size_t size)
+size_t runtime::gpu::GPUAllocator::reserve_workspace(size_t size, bool zero_initialize)
 {
     size_t offset = m_manager->m_workspace_manager.allocate(size);
     m_active.push(offset);
@@ -117,7 +117,12 @@ size_t runtime::gpu::GPUAllocator::reserve_workspace(size_t size)
             throw std::runtime_error("An attempt was made to use unallocated device memory.");
         }
         auto gpu_mem = static_cast<uint8_t*>(manager->m_workspace);
-        return static_cast<void*>(gpu_mem + offset);
+        auto workspace = static_cast<void*>(gpu_mem + offset);
+        if (zero_initialize)
+        {
+            runtime::gpu::cuda_memset(workspace, 0, size);
+        }
+        return workspace;
     };
     return m_manager->m_primitive_emitter->insert(mem_primitive);
 }

src/ngraph/runtime/gpu/gpu_memory_manager.hpp

@@ -43,7 +43,7 @@ namespace ngraph
 
                 ~GPUAllocator();
                 size_t reserve_argspace(const void* data, size_t size);
-                size_t reserve_workspace(size_t size);
+                size_t reserve_workspace(size_t size, bool zero_initialize = true);
 
             private:
                 GPUMemoryManager* m_manager;