sched: Clean up some f_b_g() comments
The existing comment tends to grow state (as it already has), split it
up and place it near the actual tests.
Signed-off-by: Peter Zijlstra <a.p.zijlstra@chello.nl>
Cc: Nikhil Rao <ncrao@google.com>
Cc: Venkatesh Pallipadi <venki@google.com>
Cc: Suresh Siddha <suresh.b.siddha@intel.com>
Cc: Mike Galbraith <efault@gmx.de>
LKML-Reference: <new-submission>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
diff --git a/kernel/sched_fair.c b/kernel/sched_fair.c
index cd18600..03496eb 100644
--- a/kernel/sched_fair.c
+++ b/kernel/sched_fair.c
@@ -3113,19 +3113,9 @@
*/
update_sd_lb_stats(sd, this_cpu, idle, cpus, balance, &sds);
- /* Cases where imbalance does not exist from POV of this_cpu */
- /* 1) this_cpu is not the appropriate cpu to perform load balancing
- * at this level.
- * 2) There is no busy sibling group to pull from.
- * 3) This group is the busiest group.
- * 4) This group is more busy than the avg busieness at this
- * sched_domain.
- * 5) The imbalance is within the specified limit.
- *
- * Note: when doing newidle balance, if the local group has excess
- * capacity (i.e. nr_running < group_capacity) and the busiest group
- * does not have any capacity, we force a load balance to pull tasks
- * to the local group. In this case, we skip past checks 3, 4 and 5.
+ /*
+ * this_cpu is not the appropriate cpu to perform load balancing at
+ * this level.
*/
if (!(*balance))
goto ret;
@@ -3134,19 +3124,27 @@
check_asym_packing(sd, &sds, this_cpu, imbalance))
return sds.busiest;
+ /* There is no busy sibling group to pull tasks from */
if (!sds.busiest || sds.busiest_nr_running == 0)
goto out_balanced;
- /* SD_BALANCE_NEWIDLE trumps SMP nice when underutilized */
+ /* SD_BALANCE_NEWIDLE trumps SMP nice when underutilized */
if (idle == CPU_NEWLY_IDLE && sds.this_has_capacity &&
!sds.busiest_has_capacity)
goto force_balance;
+ /*
+ * If the local group is more busy than the selected busiest group
+ * don't try and pull any tasks.
+ */
if (sds.this_load >= sds.max_load)
goto out_balanced;
+ /*
+ * Don't pull any tasks if this group is already above the domain
+ * average load.
+ */
sds.avg_load = (SCHED_LOAD_SCALE * sds.total_load) / sds.total_pwr;
-
if (sds.this_load >= sds.avg_load)
goto out_balanced;
