sched: Remove forced2_migrations stats

This build warning:

 kernel/sched.c: In function 'set_task_cpu':
 kernel/sched.c:2070: warning: unused variable 'old_rq'

Made me realize that the forced2_migrations stat looks pretty
pointless (and a misnomer) - remove it.

Cc: Peter Zijlstra <a.p.zijlstra@chello.nl>
Cc: Mike Galbraith <efault@gmx.de>
LKML-Reference: <new-submission>
Signed-off-by: NIngo Molnar <mingo@elte.hu>

include/linux/sched.h

@@ -1174,7 +1174,6 @@ struct sched_entity {
 	u64			nr_failed_migrations_running;
 	u64			nr_failed_migrations_hot;
 	u64			nr_forced_migrations;
-	u64			nr_forced2_migrations;
 
 	u64			nr_wakeups;
 	u64			nr_wakeups_sync;

kernel/sched.c

@@ -2067,7 +2067,6 @@ task_hot(struct task_struct *p, u64 now, struct sched_domain *sd)
 void set_task_cpu(struct task_struct *p, unsigned int new_cpu)
 {
 	int old_cpu = task_cpu(p);
-	struct rq *old_rq = cpu_rq(old_cpu);
 	struct cfs_rq *old_cfsrq = task_cfs_rq(p),
 		      *new_cfsrq = cpu_cfs_rq(old_cfsrq, new_cpu);
 
@@ -2075,10 +2074,6 @@ void set_task_cpu(struct task_struct *p, unsigned int new_cpu)
 
 	if (old_cpu != new_cpu) {
 		p->se.nr_migrations++;
-#ifdef CONFIG_SCHEDSTATS
-		if (task_hot(p, old_rq->clock, NULL))
-			schedstat_inc(p, se.nr_forced2_migrations);
-#endif
 		perf_sw_event(PERF_COUNT_SW_CPU_MIGRATIONS,
 				     1, 1, NULL, 0);
 	}
@@ -2521,7 +2516,6 @@ static void __sched_fork(struct task_struct *p)
 	p->se.nr_failed_migrations_running	= 0;
 	p->se.nr_failed_migrations_hot		= 0;
 	p->se.nr_forced_migrations		= 0;
-	p->se.nr_forced2_migrations		= 0;
 
 	p->se.nr_wakeups			= 0;
 	p->se.nr_wakeups_sync			= 0;

kernel/sched_debug.c

@@ -432,7 +432,6 @@ void proc_sched_show_task(struct task_struct *p, struct seq_file *m)
 	P(se.nr_failed_migrations_running);
 	P(se.nr_failed_migrations_hot);
 	P(se.nr_forced_migrations);
-	P(se.nr_forced2_migrations);
 	P(se.nr_wakeups);
 	P(se.nr_wakeups_sync);
 	P(se.nr_wakeups_migrate);
@@ -508,7 +507,6 @@ void proc_sched_set_task(struct task_struct *p)
 	p->se.nr_failed_migrations_running	= 0;
 	p->se.nr_failed_migrations_hot		= 0;
 	p->se.nr_forced_migrations		= 0;
-	p->se.nr_forced2_migrations		= 0;
 	p->se.nr_wakeups			= 0;
 	p->se.nr_wakeups_sync			= 0;
 	p->se.nr_wakeups_migrate		= 0;