Rework multithreading threshold

Author: martin-frbg

interface/syrk.c

@@ -44,6 +44,7 @@
 #endif
 
 #ifndef COMPLEX
+#define SMP_THRESHOLD_MIN 109944.
 #ifdef XDOUBLE
 #define ERROR_NAME "QSYRK "
 #elif defined(DOUBLE)
@@ -52,6 +53,7 @@
 #define ERROR_NAME "SSYRK "
 #endif
 #else
+#define SMP_THRESHOLD_MIN 14824.
 #ifndef HEMM
 #ifdef XDOUBLE
 #define ERROR_NAME "XSYRK "
@@ -71,6 +73,10 @@
 #endif
 #endif
 
+#ifndef GEMM_MULTITHREAD_THRESHOLD
+#define GEMM_MULTITHREAD_THRESHOLD 4
+#endif
+
 static int (*syrk[])(blas_arg_t *, BLASLONG *, BLASLONG *, FLOAT *, FLOAT *, BLASLONG) = {
 #ifndef HEMM
   SYRK_UN, SYRK_UC, SYRK_LN, SYRK_LC,
@@ -101,6 +107,7 @@ void NAME(char *UPLO, char *TRANS,
   FLOAT *sa, *sb;
 
 #ifdef SMP
+  int NNK;
 #ifdef USE_SIMPLE_THREADED_LEVEL3
 #ifndef COMPLEX
 #ifdef XDOUBLE
@@ -225,6 +232,8 @@ void CNAME(enum CBLAS_ORDER order, enum CBLAS_UPLO Uplo, enum CBLAS_TRANSPOSE Tr
   FLOAT *sa, *sb;
 
 #ifdef SMP
+int NNK;
+
 #ifdef USE_SIMPLE_THREADED_LEVEL3
 #ifndef COMPLEX
 #ifdef XDOUBLE
@@ -354,26 +363,20 @@ void CNAME(enum CBLAS_ORDER order, enum CBLAS_UPLO Uplo, enum CBLAS_TRANSPOSE Tr
 #endif
 
   args.common = NULL;
-#ifndef COMPLEX
-#ifdef DOUBLE
-  if (args.n < 100)
-#else
-  if (args.n < 200)
-#endif
-#else
-  if (args.n < 65)
-#endif
+
+  NNK = (double)(args.n+1)*(double)args.n*(double)args.k;
+  if (NNK <= (SMP_THRESHOLD_MIN * GEMM_MULTITHREAD_THRESHOLD)) {
   args.nthreads = 1;
-  else
+  } else {
   args.nthreads = num_cpu_avail(3);
+  }
 
   if (args.nthreads == 1) {
 #endif
 
     (syrk[(uplo << 1) | trans ])(&args, NULL, NULL, sa, sb, 0);
 
 #ifdef SMP
-
   } else {
 
 #ifndef USE_SIMPLE_THREADED_LEVEL3