sched: Remove sched_switch

Currently we don't utilize the sched_switch field anymore.

But, simply removing sched_switch field from the middle of the
sched_stat output will break tools.

So, to stay compatible we hardcode it to zero and remove the
field from the scheduler data structures.

Update the schedstat documentation accordingly.

Signed-off-by: Rakib Mullick <rakib.mullick@gmail.com>
Signed-off-by: Peter Zijlstra <a.p.zijlstra@chello.nl>
Link: http://lkml.kernel.org/r/1327422836.27181.5.camel@localhost.localdomain
Signed-off-by: Ingo Molnar <mingo@elte.hu>

Documentation/scheduler/sched-stats.txt

@@ -38,7 +38,8 @@ First field is a sched_yield() statistic:
      1) # of times sched_yield() was called
 
 Next three are schedule() statistics:
-     2) # of times we switched to the expired queue and reused it
+     2) This field is a legacy array expiration count field used in the O(1)
+	scheduler. We kept it for ABI compatibility, but it is always set to zero.
      3) # of times schedule() was called
      4) # of times schedule() left the processor idle
 

kernel/sched/debug.c

@@ -288,7 +288,6 @@ static void print_cpu(struct seq_file *m, int cpu)
 
 	P(yld_count);
 
-	P(sched_switch);
 	P(sched_count);
 	P(sched_goidle);
 #ifdef CONFIG_SMP

kernel/sched/sched.h

@@ -462,7 +462,6 @@ struct rq {
 	unsigned int yld_count;
 
 	/* schedule() stats */
-	unsigned int sched_switch;
 	unsigned int sched_count;
 	unsigned int sched_goidle;
 

kernel/sched/stats.c

@@ -32,9 +32,9 @@ static int show_schedstat(struct seq_file *seq, void *v)
 
 		/* runqueue-specific stats */
 		seq_printf(seq,
-		    "cpu%d %u %u %u %u %u %u %llu %llu %lu",
+		    "cpu%d %u 0 %u %u %u %u %llu %llu %lu",
 		    cpu, rq->yld_count,
-		    rq->sched_switch, rq->sched_count, rq->sched_goidle,
+		    rq->sched_count, rq->sched_goidle,
 		    rq->ttwu_count, rq->ttwu_local,
 		    rq->rq_cpu_time,
 		    rq->rq_sched_info.run_delay, rq->rq_sched_info.pcount);