now use sysinfo to determine amount of memory available on the machine

src/low_level_utils.cpp

@@ -9,6 +9,7 @@
 #include <iostream>
 #include <sys/stat.h>
 #include <sys/sysctl.h>
+#include <sys/sysinfo.h>
 #include "low_level_utils.h"
 
 using namespace std;
@@ -52,7 +53,16 @@ unsigned long getNodePhysMemory() {
     }
     mem /=  1 * 1024 * 1024 * 1024;
 #else
-    cout<<"ROCK has not been tested on this operating system, please contact author."<<endl;
+    struct sysinfo si;
+    int ret=sysinfo(&si);
+    if (ret==-1) {
+        cout<<"Couldn't determine how much RAM is usable on your system."<<errno<<endl;
+        mem=0;
+    }
+    mem=si.totalram;
+    mem /=  1 * 1024 * 1024 * 1024;
+    cout<<"total RAM="<<mem<<endl;
+//cout<<"ROCK has not been tested on this operating system, please contact author."<<endl;
 #endif
 
     return (unsigned long)mem;