[PATCH] sched: schedstats update for balance on fork

Add SCHEDSTAT statistics for sched-balance-fork.

Signed-off-by: Nick Piggin <nickpiggin@yahoo.com.au>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>

diff --git a/include/linux/sched.h b/include/linux/sched.h
index 613491d..36a1078 100644 (file)
--- a/include/linux/sched.h
+++ b/include/linux/sched.h
@@ -517,10 +517,16 @@ struct sched_domain {
        unsigned long alb_failed;
        unsigned long alb_pushed;
 
-       /* sched_balance_exec() stats */
-       unsigned long sbe_attempts;
+       /* SD_BALANCE_EXEC stats */
+       unsigned long sbe_cnt;
+       unsigned long sbe_balanced;
        unsigned long sbe_pushed;
 
+       /* SD_BALANCE_FORK stats */
+       unsigned long sbf_cnt;
+       unsigned long sbf_balanced;
+       unsigned long sbf_pushed;
+
        /* try_to_wake_up() stats */
        unsigned long ttwu_wake_remote;
        unsigned long ttwu_move_affine;

diff --git a/kernel/sched.c b/kernel/sched.c
index 7ecc237..2711130 100644 (file)
--- a/kernel/sched.c
+++ b/kernel/sched.c
@@ -309,7 +309,7 @@ static inline void task_rq_unlock(runqueue_t *rq, unsigned long *flags)
  * bump this up when changing the output format or the meaning of an existing
  * format, so that tools can adapt (or abort)
  */
-#define SCHEDSTAT_VERSION 11
+#define SCHEDSTAT_VERSION 12
 
 static int show_schedstat(struct seq_file *seq, void *v)
 {
@@ -356,9 +356,10 @@ static int show_schedstat(struct seq_file *seq, void *v)
                                    sd->lb_nobusyq[itype],
                                    sd->lb_nobusyg[itype]);
                        }
-                       seq_printf(seq, " %lu %lu %lu %lu %lu %lu %lu %lu\n",
+                       seq_printf(seq, " %lu %lu %lu %lu %lu %lu %lu %lu %lu %lu %lu %lu\n",
                            sd->alb_cnt, sd->alb_failed, sd->alb_pushed,
-                           sd->sbe_pushed, sd->sbe_attempts,
+                           sd->sbe_cnt, sd->sbe_balanced, sd->sbe_pushed,
+                           sd->sbf_cnt, sd->sbf_balanced, sd->sbf_pushed,
                            sd->ttwu_wake_remote, sd->ttwu_move_affine, sd->ttwu_move_balance);
                }
 #endif
@@ -1264,24 +1265,34 @@ void fastcall wake_up_new_task(task_t * p, unsigned long clone_flags)
                        sd = tmp;
 
        if (sd) {
+               int new_cpu;
                struct sched_group *group;
 
+               schedstat_inc(sd, sbf_cnt);
                cpu = task_cpu(p);
                group = find_idlest_group(sd, p, cpu);
-               if (group) {
-                       int new_cpu;
-                       new_cpu = find_idlest_cpu(group, cpu);
-                       if (new_cpu != -1 && new_cpu != cpu &&
-                                       cpu_isset(new_cpu, p->cpus_allowed)) {
-                               set_task_cpu(p, new_cpu);
-                               task_rq_unlock(rq, &flags);
-                               rq = task_rq_lock(p, &flags);
-                               cpu = task_cpu(p);
-                       }
+               if (!group) {
+                       schedstat_inc(sd, sbf_balanced);
+                       goto no_forkbalance;
+               }
+
+               new_cpu = find_idlest_cpu(group, cpu);
+               if (new_cpu == -1 || new_cpu == cpu) {
+                       schedstat_inc(sd, sbf_balanced);
+                       goto no_forkbalance;
+               }
+
+               if (cpu_isset(new_cpu, p->cpus_allowed)) {
+                       schedstat_inc(sd, sbf_pushed);
+                       set_task_cpu(p, new_cpu);
+                       task_rq_unlock(rq, &flags);
+                       rq = task_rq_lock(p, &flags);
+                       cpu = task_cpu(p);
                }
        }
-#endif
 
+no_forkbalance:
+#endif
        /*
         * We decrease the sleep average of forking parents
         * and children as well, to keep max-interactive tasks
@@ -1618,30 +1629,28 @@ void sched_exec(void)
        struct sched_domain *tmp, *sd = NULL;
        int new_cpu, this_cpu = get_cpu();
 
-       /* Prefer the current CPU if there's only this task running */
-       if (this_rq()->nr_running <= 1)
-               goto out;
-
        for_each_domain(this_cpu, tmp)
                if (tmp->flags & SD_BALANCE_EXEC)
                        sd = tmp;
 
        if (sd) {
                struct sched_group *group;
-               schedstat_inc(sd, sbe_attempts);
+               schedstat_inc(sd, sbe_cnt);
                group = find_idlest_group(sd, current, this_cpu);
-               if (!group)
+               if (!group) {
+                       schedstat_inc(sd, sbe_balanced);
                        goto out;
+               }
                new_cpu = find_idlest_cpu(group, this_cpu);
-               if (new_cpu == -1)
+               if (new_cpu == -1 || new_cpu == this_cpu) {
+                       schedstat_inc(sd, sbe_balanced);
                        goto out;
-
-               if (new_cpu != this_cpu) {
-                       schedstat_inc(sd, sbe_pushed);
-                       put_cpu();
-                       sched_migrate_task(current, new_cpu);
-                       return;
                }
+
+               schedstat_inc(sd, sbe_pushed);
+               put_cpu();
+               sched_migrate_task(current, new_cpu);
+               return;
        }
 out:
        put_cpu();