more task_struct size reduction, by moving the debugging/instrumentation
fields to under CONFIG_SCHEDSTATS:
 (i386, nodebug):
                          size
                          ----
     pre-CFS              1328
         CFS              1472
         CFS+patch        1376
Signed-off-by: Ingo Molnar <mingo@elte.hu>
        struct rb_node          run_node;
        unsigned int            on_rq;
 
+       u64                     exec_start;
+       u64                     sum_exec_runtime;
        u64                     wait_start_fair;
+       u64                     sleep_start_fair;
+
+#ifdef CONFIG_SCHEDSTATS
        u64                     wait_start;
-       u64                     exec_start;
+       u64                     wait_max;
+       s64                     sum_wait_runtime;
+
        u64                     sleep_start;
-       u64                     sleep_start_fair;
-       u64                     block_start;
        u64                     sleep_max;
+       s64                     sum_sleep_runtime;
+
+       u64                     block_start;
        u64                     block_max;
        u64                     exec_max;
-       u64                     wait_max;
-       u64                     last_ran;
 
-       u64                     sum_exec_runtime;
-       s64                     sum_wait_runtime;
-       s64                     sum_sleep_runtime;
        unsigned long           wait_runtime_overruns;
        unsigned long           wait_runtime_underruns;
+#endif
+
 #ifdef CONFIG_FAIR_GROUP_SCHED
        struct sched_entity     *parent;
        /* rq on which this entity is (to be) queued: */