[PATCH 11/30] sched: kill task_group balancing

Peter Zijlstra
2008-06-27T12:06:57Z

[-- Attachment #1: sched-group-balance-fix.patch --]
[-- Type: text/plain, Size: 1718 bytes --]

From: Srivatsa Vaddagiri <vatsa@linux.vnet.ibm.com>

The idea was to balance groups until we've reached the global goal, however
Vatsa rightly pointed out that we might never reach that goal this way -
hence take out this logic.

[ the initial rationale for this 'feature' was to promote max concurrency
within a group - it does not however affect fairness ]

Reported-by: Srivatsa Vaddagiri <vatsa@linux.vnet.ibm.com>
Signed-off-by: Peter Zijlstra <a.p.zijlstra@chello.nl>
---
kernel/sched_fair.c | 15 ++-------------
1 file changed, 2 insertions(+), 13 deletions(-)

Index: linux-2.6/kernel/sched_fair.c
===================================================================
--- linux-2.6.orig/kernel/sched_fair.c
+++ linux-2.6/kernel/sched_fair.c
@@ -1427,9 +1427,7 @@ load_balance_fair(struct rq *this_rq, in

rcu_read_lock();
list_for_each_entry(tg, &task_groups, list) {
- long imbalance;
- unsigned long this_weight, busiest_weight;
- long rem_load, max_load, moved_load;
+ long rem_load, moved_load;

/*
* empty group
@@ -1440,17 +1438,8 @@ load_balance_fair(struct rq *this_rq, in
rem_load = rem_load_move * aggregate(tg, this_cpu)->rq_weight;
rem_load /= aggregate(tg, this_cpu)->load + 1;

- this_weight = tg->cfs_rq[this_cpu]->task_weight;
- busiest_weight = tg->cfs_rq[busiest_cpu]->task_weight;
-
- imbalance = (busiest_weight - this_weight) / 2;
-
- if (imbalance < 0)
- imbalance = busiest_weight;
-
- max_load = max(rem_load, imbalance);
moved_load = __load_balance_fair(this_rq, this_cpu, busiest,
- max_load, sd, idle, all_pinned, this_best_prio,
+ rem_load, sd, idle, all_pinned, this_best_prio,
tg->cfs_rq[busiest_cpu]);

if (!moved_load)

--