Merge pull request #1491 from martin-frbg/ddot_mt

Add multithreading support for Haswell DDOT

Author: martin-frbg

kernel/x86_64/ddot.c

@@ -43,6 +43,12 @@ USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
 #include "ddot_microk_sandy-2.c"
 #endif
 
+#if !defined(DSDOT)
+#define RETURN_TYPE     FLOAT
+#else
+#define RETURN_TYPE     double
+#endif
+
 
 #ifndef HAVE_KERNEL_8
 
@@ -71,7 +77,7 @@ static void ddot_kernel_8(BLASLONG n, FLOAT *x, FLOAT *y, FLOAT *d)
 
 #endif
 
-FLOAT CNAME(BLASLONG n, FLOAT *x, BLASLONG inc_x, FLOAT *y, BLASLONG inc_y)
+static FLOAT dot_compute(BLASLONG n, FLOAT *x, BLASLONG inc_x, FLOAT *y, BLASLONG inc_y)
 {
 	BLASLONG i=0;
 	BLASLONG ix=0,iy=0;
@@ -139,4 +145,63 @@ FLOAT CNAME(BLASLONG n, FLOAT *x, BLASLONG inc_x, FLOAT *y, BLASLONG inc_y)
 
 }
 
+#if defined(SMP)
+static int dot_thread_function(BLASLONG n, BLASLONG dummy0,
+        BLASLONG dummy1, FLOAT dummy2, FLOAT *x, BLASLONG inc_x, FLOAT *y,
+        BLASLONG inc_y, RETURN_TYPE *result, BLASLONG dummy3)
+{
+        *(RETURN_TYPE *)result = dot_compute(n, x, inc_x, y, inc_y);
+
+        return 0;
+}
+
+extern int blas_level1_thread_with_return_value(int mode, BLASLONG m, BLASLONG n,
+        BLASLONG k, void *alpha, void *a, BLASLONG lda, void *b, BLASLONG ldb,
+        void *c, BLASLONG ldc, int (*function)(), int nthreads);
+#endif
 
+FLOAT CNAME(BLASLONG n, FLOAT *x, BLASLONG inc_x, FLOAT *y, BLASLONG inc_y)
+{
+#if defined(SMP)
+	int nthreads;
+	FLOAT dummy_alpha;
+#endif
+	FLOAT dot = 0.0;
+
+#if defined(SMP)
+	nthreads = num_cpu_avail(1);
+
+	if (inc_x == 0 || inc_y == 0)
+		nthreads = 1;
+
+	if (n <= 10000)
+		nthreads = 1;
+
+	if (nthreads == 1) {
+		dot = dot_compute(n, x, inc_x, y, inc_y);
+	} else {
+		int mode, i;
+		char result[MAX_CPU_NUMBER * sizeof(double) * 2];
+		RETURN_TYPE *ptr;
+
+#if !defined(DOUBLE)
+		mode = BLAS_SINGLE  | BLAS_REAL;
+#else
+		mode = BLAS_DOUBLE  | BLAS_REAL;
+#endif
+		blas_level1_thread_with_return_value(mode, n, 0, 0, &dummy_alpha,
+				   x, inc_x, y, inc_y, result, 0,
+				   ( void *)dot_thread_function, nthreads);
+
+		ptr = (RETURN_TYPE *)result;
+		for (i = 0; i < nthreads; i++) {
+			dot = dot + (*ptr);
+			ptr = (RETURN_TYPE *)(((char *)ptr) + sizeof(double) * 2);
+		}
+	}
+#else
+	dot = dot_compute(n, x, inc_x, y, inc_y);
+#endif
+
+	return dot;
+}