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sched: simplify the group load balancer

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While thinking about the previous patch - I realized that using per domain
aggregate load values in load_balance_fair() is wrong. We should use the
load value for that CPU.

By not needing per domain hierarchical load values we don't need to store
per domain aggregate shares, which greatly simplifies all the math.

It basically falls apart in two separate computations:
 - per domain update of the shares
 - per CPU update of the hierarchical load

Also get rid of the move_group_shares() stuff - just re-compute the shares
again after a successful load balance.

Signed-off-by: Peter Zijlstra <a.p.zijlstra@chello.nl>
Cc: Srivatsa Vaddagiri <vatsa@linux.vnet.ibm.com>
Cc: Mike Galbraith <efault@gmx.de>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
This commit is contained in:
Peter Zijlstra
2008-06-27 13:41:23 +02:00
committed by Ingo Molnar
parent a25b5aca87
commit c8cba857b4
2 changed files with 74 additions and 231 deletions
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15
kernel/sched_fair.c
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@@ -1421,17 +1421,20 @@ load_balance_fair(struct rq *this_rq, int this_cpu, struct rq *busiest,
struct task_group *tg;
rcu_read_lock();
update_h_load(busiest_cpu);
list_for_each_entry(tg, &task_groups, list) {
struct cfs_rq *busiest_cfs_rq = tg->cfs_rq[busiest_cpu];
long rem_load, moved_load;
/*
* empty group
*/
if (!tg->cfs_rq[busiest_cpu]->task_weight)
if (!busiest_cfs_rq->task_weight)
continue;
rem_load = rem_load_move * aggregate(tg, this_cpu)->rq_weight;
rem_load /= aggregate(tg, this_cpu)->load + 1;
rem_load = rem_load_move * busiest_cfs_rq->load.weight;
rem_load /= busiest_cfs_rq->h_load + 1;
moved_load = __load_balance_fair(this_rq, this_cpu, busiest,
rem_load, sd, idle, all_pinned, this_best_prio,
@@ -1440,10 +1443,8 @@ load_balance_fair(struct rq *this_rq, int this_cpu, struct rq *busiest,
if (!moved_load)
continue;
move_group_shares(tg, this_cpu, sd, busiest_cpu, this_cpu);
moved_load *= aggregate(tg, this_cpu)->load;
moved_load /= aggregate(tg, this_cpu)->rq_weight + 1;
moved_load *= busiest_cfs_rq->h_load;
moved_load /= busiest_cfs_rq->load.weight + 1;
rem_load_move -= moved_load;
if (rem_load_move < 0)