[PATCH 29/30] sched: incremental effective_load()

Peter Zijlstra
2008-06-27T12:01:51Z

[-- Attachment #1: sched-incremental-wake_affine.patch --]
[-- Type: text/plain, Size: 2182 bytes --]

Increase the accuracy of the effective_load values.

Not only consider the current increment (as per the attempted wakeup), but
also consider the delta between when we last adjusted the shares and the
current situation.

Signed-off-by: Peter Zijlstra <peterz@infradead.org>
---
kernel/sched.c | 6 ++++++
kernel/sched_fair.c | 18 +++++++++++++++---
2 files changed, 21 insertions(+), 3 deletions(-)

Index: linux-2.6/kernel/sched_fair.c
===================================================================
--- linux-2.6.orig/kernel/sched_fair.c
+++ linux-2.6/kernel/sched_fair.c
@@ -1074,10 +1074,22 @@ static inline int wake_idle(int cpu, str
static const struct sched_class fair_sched_class;

#ifdef CONFIG_FAIR_GROUP_SCHED
-static unsigned long effective_load(struct task_group *tg, int cpu,
- unsigned long wl, unsigned long wg)
+static long effective_load(struct task_group *tg, int cpu,
+ long wl, long wg)
{
struct sched_entity *se = tg->se[cpu];
+ long more_w;
+
+ if (!tg->parent)
+ return wl;
+
+ /*
+ * Instead of using this increment, also add the difference
+ * between when the shares were last updated and now.
+ */
+ more_w = se->my_q->load.weight - se->my_q->rq_weight;
+ wl += more_w;
+ wg += more_w;

for_each_sched_entity(se) {
#define D(n) (likely(n) ? (n) : 1)
@@ -1086,7 +1098,7 @@ static unsigned long effective_load(stru

S = se->my_q->tg->shares;
s = se->my_q->shares;
- rw = se->my_q->load.weight;
+ rw = se->my_q->rq_weight;

a = S*(rw + wl);
b = S*rw + s*wg;
Index: linux-2.6/kernel/sched.c
===================================================================
--- linux-2.6.orig/kernel/sched.c
+++ linux-2.6/kernel/sched.c
@@ -427,6 +427,11 @@ struct cfs_rq {
* this cpu's part of tg->shares
*/
unsigned long shares;
+
+ /*
+ * load.weight at the time we set shares
+ */
+ unsigned long rq_weight;
#endif
#endif
};
@@ -1527,6 +1532,7 @@ __update_group_shares_cpu(struct task_gr
* record the actual number of shares, not the boosted amount.
*/
tg->cfs_rq[cpu]->shares = boost ? 0 : shares;
+ tg->cfs_rq[cpu]->rq_weight = rq_weight;

if (shares < MIN_SHARES)
shares = MIN_SHARES;

--