Added cuda::gemm()

dlib/dnn/cublas_dlibapi.cpp

@@ -14,24 +14,63 @@ namespace dlib
     namespace cuda 
     {
 
-    // -----------------------------------------------------------------------------------
+    // ----------------------------------------------------------------------------------------
 
-        cublas_context::
-        cublas_context()
+        // TODO, make into a macro that prints more information like the line number, etc.
+        static void check(cublasStatus_t s)
         {
-            // TODO
+            switch(s)
+            {
+                case CUBLAS_STATUS_SUCCESS: return;
+                case CUBLAS_STATUS_NOT_INITIALIZED: 
+                    throw cublas_error("CUDA Runtime API initialization failed.");
+                case CUBLAS_STATUS_ALLOC_FAILED: 
+                    throw cublas_error("CUDA Resources could not be allocated.");
+                default:
+                    throw cublas_error("A call to cuBLAS failed");
+            }
         }
 
-        cublas_context::
-        ~cublas_context()
+    // -----------------------------------------------------------------------------------
+
+        class cublas_context
+        {
+        public:
+            // not copyable
+            cublas_context(const cublas_context&) = delete;
+            cublas_context& operator=(const cublas_context&) = delete;
+
+            cublas_context()
+            {
+                check(cublasCreate(&handle));
+            }
+            ~cublas_context()
+            {
+                cublasDestroy(handle);
+            }
+
+            cublasHandle_t get_handle (
+            ) const { return handle; }
+
+        private:
+
+            cublasHandle_t handle;
+        };
+
+        // TODO, there should probably be some function that is like dlibCudaSetDevice().
+        // Because people will call cudaSetDevice() expecting to set the device but for
+        // cuBLAS and cuDNN, since they have these handles, they will keep using the old
+        // devices.  So we should have something that resets these handles and does a
+        // "dlibCudaSetDevice()"
+        static cublasHandle_t context()
         {
-            // TODO
+            thread_local cublas_context c;
+            return c.get_handle();
         }
 
     // -----------------------------------------------------------------------------------
 
         void gemm (
-            cublas_context& context,
             float beta,
             tensor& dest,
             float alpha,
@@ -41,6 +80,48 @@ namespace dlib
             bool trans_rhs
         )
         {
+            // Recall that BLAS uses column major order so to deal with that we flip the
+            // order of the lhs and rhs arguments.
+            const auto transa = trans_lhs ? CUBLAS_OP_T : CUBLAS_OP_N;
+            const auto transb = trans_rhs ? CUBLAS_OP_T : CUBLAS_OP_N;
+
+            if (trans_lhs && trans_rhs)
+            {
+                DLIB_CASSERT( mat(dest).nr() == trans(mat(lhs)).nr() &&
+                              mat(dest).nc() == trans(mat(rhs)).nc() &&
+                              trans(mat(lhs)).nc() == trans(mat(rhs)).nr(),"")
+            }
+            else if (!trans_lhs && trans_rhs)
+            {
+                DLIB_CASSERT( mat(dest).nr() == mat(lhs).nr() &&
+                              mat(dest).nc() == trans(mat(rhs)).nc() &&
+                              mat(lhs).nc() == trans(mat(rhs)).nr(),"")
+            }
+            else if (trans_lhs && !trans_rhs)
+            {
+                DLIB_CASSERT( mat(dest).nr() == trans(mat(lhs)).nr() &&
+                              mat(dest).nc() == mat(rhs).nc() &&
+                              trans(mat(lhs)).nc() == mat(rhs).nr(),"")
+            }
+            else
+            {
+                DLIB_CASSERT( mat(dest).nr() == mat(lhs).nr() &&
+                              mat(dest).nc() == mat(rhs).nc() &&
+                              mat(lhs).nc() == mat(rhs).nr(),"")
+            }
+
+            const int m = mat(dest).nr();
+            const int n = mat(dest).nc();
+            const int k = trans_rhs ? mat(rhs).nc() : mat(rhs).nr();
+            check(cublasSgemm(context(),
+                              transb,
+                              transa, 
+                              m, n, k,
+                              &alpha,
+                              rhs.device(), mat(rhs).nc(),
+                              lhs.device(), mat(lhs).nc(),
+                              &beta,
+                              dest.device(), mat(dest).nc()));
         }
 
     // ------------------------------------------------------------------------------------

dlib/dnn/cublas_dlibapi.h

@@ -20,34 +20,9 @@ namespace dlib
             cublas_error(const std::string& message): error(message) {}
         };
 
-    // -----------------------------------------------------------------------------------
-
-        class cublas_context
-        {
-        public:
-            // not copyable
-            cublas_context(const cublas_context&) = delete;
-            cublas_context& operator=(const cublas_context&) = delete;
-            // but is movable
-            cublas_context(cublas_context&& item) : cublas_context() { swap(item); }
-            cublas_context& operator=(cublas_context&& item) { swap(item); return *this; }
-
-            cublas_context();
-            ~cublas_context();
-
-            const void* get_handle (
-            ) const { return handle; }
-
-        private:
-            void swap(cublas_context& item) { std::swap(handle, item.handle); }
-
-            void* handle;
-        };
-
     // -----------------------------------------------------------------------------------
 
         void gemm (
-            cublas_context& context,
             float beta,
             tensor& dest,
             float alpha,
@@ -56,6 +31,19 @@ namespace dlib
             const tensor& rhs,
             bool trans_rhs
         );
+        /*!
+            requires
+                - The dimensions of lhs and rhs must be compatible for matrix
+                  multiplication.  In particular:
+                    - Let L == trans_lhs ? trans(mat(lhs)) : mat(lhs)
+                    - Let R == trans_rhs ? trans(mat(rhs)) : mat(rhs)
+                    - Let D == mat(dest)
+                    - D.nr() == L.nr() && D.nc() == R.nc()
+                      (i.e. dest must be preallocated and have the correct output dimensions)
+                    - L.nc() == R.nr()
+            ensures
+                - performs: dest = alpha*L*R + beta*mat(dest)
+        !*/
 
     // ------------------------------------------------------------------------------------