Change the default advise mode to "discard"

This avoids to swap out other process memory.

HISTORY

@@ -10,6 +10,9 @@ SnapRAID HISTORY
  * More efficient 'pool' command that updates only the links
    that need to be updated. This ensures that no change is
    done, avoiding to trigger a directory rescan of other programs.
+ * In Linux use by default the advise "discard" mode instead of "flush".
+   This avoids to swap-out the other process memory, leaving the system
+   more responsive.
  * Changed the --test-io-stats screen to print the file name in process
    for each disk.
 

cmdline/state.c

@@ -538,7 +538,7 @@ void state_config(struct snapraid_state* state, const char* path, const char* co
 		state->file_mode = state->opt.file_mode;
 	} else {
 		/* default mode, if nothing is specified */
-		state->file_mode = ADVISE_FLUSH;
+		state->file_mode = ADVISE_DISCARD;
 	}
 
 	/* store current command */