u64 clock_offset, fair_clock_offset;
 
        clock_offset = old_rq->clock - new_rq->clock;
-       fair_clock_offset = old_rq->cfs.fair_clock -
-                                                new_rq->cfs.fair_clock;
-       if (p->se.wait_start)
-               p->se.wait_start -= clock_offset;
+       fair_clock_offset = old_rq->cfs.fair_clock - new_rq->cfs.fair_clock;
+
        if (p->se.wait_start_fair)
                p->se.wait_start_fair -= fair_clock_offset;
+       if (p->se.sleep_start_fair)
+               p->se.sleep_start_fair -= fair_clock_offset;
+
+#ifdef CONFIG_SCHEDSTATS
+       if (p->se.wait_start)
+               p->se.wait_start -= clock_offset;
        if (p->se.sleep_start)
                p->se.sleep_start -= clock_offset;
        if (p->se.block_start)
                p->se.block_start -= clock_offset;
-       if (p->se.sleep_start_fair)
-               p->se.sleep_start_fair -= fair_clock_offset;
+#endif
 
        __set_task_cpu(p, new_cpu);
 }
 static void __sched_fork(struct task_struct *p)
 {
        p->se.wait_start_fair           = 0;
-       p->se.wait_start                = 0;
        p->se.exec_start                = 0;
        p->se.sum_exec_runtime          = 0;
        p->se.delta_exec                = 0;
        p->se.delta_fair_run            = 0;
        p->se.delta_fair_sleep          = 0;
        p->se.wait_runtime              = 0;
+       p->se.sleep_start_fair          = 0;
+
+#ifdef CONFIG_SCHEDSTATS
+       p->se.wait_start                = 0;
        p->se.sum_wait_runtime          = 0;
        p->se.sum_sleep_runtime         = 0;
        p->se.sleep_start               = 0;
-       p->se.sleep_start_fair          = 0;
        p->se.block_start               = 0;
        p->se.sleep_max                 = 0;
        p->se.block_max                 = 0;
        p->se.wait_max                  = 0;
        p->se.wait_runtime_overruns     = 0;
        p->se.wait_runtime_underruns    = 0;
+#endif
 
        INIT_LIST_HEAD(&p->run_list);
        p->se.on_rq = 0;
        do_each_thread(g, p) {
                p->se.fair_key                  = 0;
                p->se.wait_runtime              = 0;
+               p->se.exec_start                = 0;
                p->se.wait_start_fair           = 0;
+               p->se.sleep_start_fair          = 0;
+#ifdef CONFIG_SCHEDSTATS
                p->se.wait_start                = 0;
-               p->se.exec_start                = 0;
                p->se.sleep_start               = 0;
-               p->se.sleep_start_fair          = 0;
                p->se.block_start               = 0;
+#endif
                task_rq(p)->cfs.fair_clock      = 0;
                task_rq(p)->clock               = 0;
 
 
                (long long)p->se.wait_runtime,
                (long long)(p->nvcsw + p->nivcsw),
                p->prio,
+#ifdef CONFIG_SCHEDSTATS
                (long long)p->se.sum_exec_runtime,
                (long long)p->se.sum_wait_runtime,
                (long long)p->se.sum_sleep_runtime,
                (long long)p->se.wait_runtime_overruns,
-               (long long)p->se.wait_runtime_underruns);
+               (long long)p->se.wait_runtime_underruns
+#else
+               0LL, 0LL, 0LL, 0LL, 0LL
+#endif
+       );
 }
 
 static void print_rq(struct seq_file *m, struct rq *rq, int rq_cpu, u64 now)
        u64 now = ktime_to_ns(ktime_get());
        int cpu;
 
-       SEQ_printf(m, "Sched Debug Version: v0.05, %s %.*s\n",
+       SEQ_printf(m, "Sched Debug Version: v0.05-v20, %s %.*s\n",
                init_utsname()->release,
                (int)strcspn(init_utsname()->version, " "),
                init_utsname()->version);
 #define P(F) \
        SEQ_printf(m, "%-25s:%20Ld\n", #F, (long long)p->F)
 
-       P(se.wait_start);
+       P(se.wait_runtime);
        P(se.wait_start_fair);
        P(se.exec_start);
-       P(se.sleep_start);
        P(se.sleep_start_fair);
+       P(se.sum_exec_runtime);
+
+#ifdef CONFIG_SCHEDSTATS
+       P(se.wait_start);
+       P(se.sleep_start);
        P(se.block_start);
        P(se.sleep_max);
        P(se.block_max);
        P(se.exec_max);
        P(se.wait_max);
-       P(se.wait_runtime);
        P(se.wait_runtime_overruns);
        P(se.wait_runtime_underruns);
        P(se.sum_wait_runtime);
-       P(se.sum_exec_runtime);
+#endif
        SEQ_printf(m, "%-25s:%20Ld\n",
                   "nr_switches", (long long)(p->nvcsw + p->nivcsw));
        P(se.load.weight);
 
 void proc_sched_set_task(struct task_struct *p)
 {
+#ifdef CONFIG_SCHEDSTATS
        p->se.sleep_max = p->se.block_max = p->se.exec_max = p->se.wait_max = 0;
        p->se.wait_runtime_overruns = p->se.wait_runtime_underruns = 0;
+#endif
        p->se.sum_exec_runtime = 0;
 }
 
 update_stats_wait_start(struct cfs_rq *cfs_rq, struct sched_entity *se, u64 now)
 {
        se->wait_start_fair = cfs_rq->fair_clock;
-       se->wait_start = now;
+       schedstat_set(se->wait_start, now);
 }
 
 /*
        }
 
        se->wait_start_fair = 0;
-       se->wait_start = 0;
+       schedstat_set(se->wait_start, 0);
 }
 
 static inline void
 
        delta_exec = now - curr->se.exec_start;
        if (unlikely((s64)delta_exec < 0))
                delta_exec = 0;
-       if (unlikely(delta_exec > curr->se.exec_max))
-               curr->se.exec_max = delta_exec;
+
+       schedstat_set(curr->se.exec_max, max(curr->se.exec_max, delta_exec));
 
        curr->se.sum_exec_runtime += delta_exec;
        curr->se.exec_start = now;