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authorPaul Turner <pjt@google.com>2011-01-14 17:57:50 -0800
committerIngo Molnar <mingo@elte.hu>2011-01-18 15:09:38 +0100
commit977dda7c9b540f48b228174346d8b31542c1e99f (patch)
tree77d40bcc72c1590dfcaeadb60e92a270bd204c52 /kernel
parentc9b5f501ef1580faa30c40c644b7691870462201 (diff)
downloadlinux-linaro-precise-977dda7c9b540f48b228174346d8b31542c1e99f.tar.gz
sched: Update effective_load() to use global share weights
Previously effective_load would approximate the global load weight present on a group taking advantage of: entity_weight = tg->shares ( lw / global_lw ), where entity_weight was provided by tg_shares_up. This worked (approximately) for an 'empty' (at tg level) cpu since we would place boost load representative of what a newly woken task would receive. However, now that load is instantaneously updated this assumption is no longer true and the load calculation is rather incorrect in this case. Fix this (and improve the general case) by re-writing effective_load to take advantage of the new shares distribution code. Signed-off-by: Paul Turner <pjt@google.com> Signed-off-by: Peter Zijlstra <a.p.zijlstra@chello.nl> LKML-Reference: <20110115015817.069769529@google.com> Signed-off-by: Ingo Molnar <mingo@elte.hu>
Diffstat (limited to 'kernel')
-rw-r--r--kernel/sched_fair.c32
1 files changed, 16 insertions, 16 deletions
diff --git a/kernel/sched_fair.c b/kernel/sched_fair.c
index c62ebae65cf..414145cf534 100644
--- a/kernel/sched_fair.c
+++ b/kernel/sched_fair.c
@@ -1362,27 +1362,27 @@ static long effective_load(struct task_group *tg, int cpu, long wl, long wg)
return wl;
for_each_sched_entity(se) {
- long S, rw, s, a, b;
+ long lw, w;
- S = se->my_q->tg->shares;
- s = se->load.weight;
- rw = se->my_q->load.weight;
+ tg = se->my_q->tg;
+ w = se->my_q->load.weight;
- a = S*(rw + wl);
- b = S*rw + s*wg;
+ /* use this cpu's instantaneous contribution */
+ lw = atomic_read(&tg->load_weight);
+ lw -= se->my_q->load_contribution;
+ lw += w + wg;
- wl = s*(a-b);
+ wl += w;
- if (likely(b))
- wl /= b;
+ if (lw > 0 && wl < lw)
+ wl = (wl * tg->shares) / lw;
+ else
+ wl = tg->shares;
- /*
- * Assume the group is already running and will
- * thus already be accounted for in the weight.
- *
- * That is, moving shares between CPUs, does not
- * alter the group weight.
- */
+ /* zero point is MIN_SHARES */
+ if (wl < MIN_SHARES)
+ wl = MIN_SHARES;
+ wl -= se->load.weight;
wg = 0;
}