Disable processor affinity by default, this is less surprising more often

README

@@ -14,6 +14,7 @@ See INSTALL.swift for install instructions.
 Usage: swift [OPTION] PARAMFILE
 
 Valid options are:
+  -a          Pin runners using processor affinity
   -c          Run with cosmological time integration
   -d          Dry run. Read the parameter file, allocate memory but does not read 
               the particles from ICs and exit before the start of time integration.

examples/main.c

@@ -52,7 +52,7 @@ void print_help_message() {
 
   printf("\nUsage: swift [OPTION] PARAMFILE\n\n");
   printf("Valid options are:\n");
-  printf("  %2s %8s %s\n", "-a", "[01]", "Use processor affinity");
+  printf("  %2s %8s %s\n", "-a", "", "Pin runners using processor affinity");
   printf("  %2s %8s %s\n", "-c", "", "Run with cosmological time integration");
   printf(
       "  %2s %8s %s\n", "-d", "",
@@ -133,7 +133,7 @@ int main(int argc, char *argv[]) {
   /* Welcome to SWIFT, you made the right choice */
   if (myrank == 0) greetings();
 
-  int with_aff = 1;
+  int with_aff = 0;
   int dry_run = 0;
   int dump_tasks = 0;
   int with_cosmology = 0;
@@ -148,13 +148,9 @@ int main(int argc, char *argv[]) {
 
   /* Parse the parameters */
   int c;
-  while ((c = getopt(argc, argv, "a:cdef:gGhst:v:y:")) != -1) switch (c) {
+  while ((c = getopt(argc, argv, "acdef:gGhst:v:y:")) != -1) switch (c) {
       case 'a':
-        if (sscanf(optarg, "%d", &with_aff) != 1) {
-          if (myrank == 0) printf("Error parsing affinity switch (-a).\n");
-          if (myrank == 0) print_help_message();
-          return 1;
-        }
+        with_aff = 1;
         break;
       case 'c':
         with_cosmology = 1;