Allow to force the number of parallel make job

This is particularly useful when using distcc

Makefile.rule

@@ -108,6 +108,10 @@ NO_AFFINITY = 1
 # Don't use parallel make.
 # NO_PARALLEL_MAKE = 1
 
+# Force number of make jobs. The default is the number of logical CPU of the host.
+# This is particularly useful when using distcc
+# MAKE_NB_JOBS = 2
+
 # If you would like to know minute performance report of GotoBLAS.
 # FUNCTION_PROFILE = 1
 

Makefile.system

@@ -139,6 +139,10 @@ NO_PARALLEL_MAKE=0
 endif
 GETARCH_FLAGS	+= -DNO_PARALLEL_MAKE=$(NO_PARALLEL_MAKE)
 
+ifdef MAKE_NB_JOBS
+GETARCH_FLAGS += -DMAKE_NB_JOBS=$(MAKE_NB_JOBS)
+endif
+
 ifeq ($(HOSTCC), loongcc)
 GETARCH_FLAGS  += -static
 endif

getarch.c

@@ -998,7 +998,9 @@ int main(int argc, char *argv[]){
 #endif
 #endif
 
-#if NO_PARALLEL_MAKE==1
+#ifdef MAKE_NB_JOBS
+    printf("MAKE += -j %d\n", MAKE_NB_JOBS);
+#elif NO_PARALLEL_MAKE==1
     printf("MAKE += -j 1\n");
 #else
 #ifndef OS_WINDOWS