optimized interface/gemv.c for multithreading

interface/gemv.c

@@ -215,9 +215,8 @@ void CNAME(enum CBLAS_ORDER order,
   int  nthreads_max = num_cpu_avail(2);
   int  nthreads_avail = nthreads_max;
 
-
   double MNK = (double) m * (double) n;
-  if ( MNK <= (128.0 * 32.0  * (double) GEMM_MULTITHREAD_THRESHOLD)  )
+  if ( MNK <= (96.0 * 24.0  * (double) GEMM_MULTITHREAD_THRESHOLD)  )
         nthreads_max = 1;
 
   if ( nthreads_max > nthreads_avail )