Change multi-threading logic for SBGEMV to be the same as SGEMV.

Author: Chip Kerchner

interface/sbgemv.c

@@ -178,21 +178,10 @@ void CNAME(enum CBLAS_ORDER order, enum CBLAS_TRANSPOSE TransA, blasint m, blasi
     if (incy < 0) {y -= (leny - 1) * incy;}
 
 #ifdef SMP
-    int thread_thres_row = 20480;
-    if (trans) {
-        if (n <= thread_thres_row) {
-            nthreads = 1;
-        } else {
-            nthreads = num_cpu_avail(1);
-        }
-    } else {
-        if (m <= thread_thres_row) {
-            nthreads = 1;
-        } else {
-            nthreads = num_cpu_avail(1);
-        }
-    }
-
+    if ( 1L * m * n < 115200L * GEMM_MULTITHREAD_THRESHOLD )
+      nthreads = 1;
+    else
+      nthreads = num_cpu_avail(2);
 
     if (nthreads == 1) {
 #endif