Merge pull request #5410 from martin-frbg/issue5404

Adjust multithreading threshold in S/DGER and add an intermediate step

Author: martin-frbg

interface/ger.c

@@ -180,8 +180,10 @@ void CNAME(enum CBLAS_ORDER order,
 
 #ifdef SMPTEST
   // Threshold chosen so that speed-up is > 1 on a Xeon E5-2630
-  if(1L * m * n > 2048L * GEMM_MULTITHREAD_THRESHOLD)
+  if(1L * m * n > 20480L * GEMM_MULTITHREAD_THRESHOLD)
     nthreads = num_cpu_avail(2);
+  else if(1L * m * n > 2048L * GEMM_MULTITHREAD_THRESHOLD)
+	  nthreads = MIN(3,num_cpu_avail(2));
   else
     nthreads = 1;