[RFC tg_shares_up improvements - v1 10/12] sched: allow update_cfs_load to update global load

pjt
2010-10-16T04:55:11Z

[-- Attachment #1: sched-tg-global_update_load.patch --]
[-- Type: text/plain, Size: 4070 bytes --]

Refactor the global load updates from update_shares_cpu() so that
update_cfs_load() can update global load when it is more than ~10% out of sync.

The new global_load parameter allows us to force an update, regardless of
the error factor so that we can synchronize w/ update_shares().

Signed-off-by: Paul Turner <pjt@google.com>

---
kernel/sched_fair.c | 42 ++++++++++++++++++++++++++++--------------
1 file changed, 28 insertions(+), 14 deletions(-)

Index: kernel/sched_fair.c
===================================================================
--- kernel/sched_fair.c.orig
+++ kernel/sched_fair.c
@@ -538,7 +538,7 @@ static u64 sched_vslice(struct cfs_rq *c
return calc_delta_fair(sched_slice(cfs_rq, se), se);
}

-static void update_cfs_load(struct cfs_rq *cfs_rq);
+static void update_cfs_load(struct cfs_rq *cfs_rq, int global_update);
static void update_cfs_shares(struct cfs_rq *cfs_rq, long weight_delta);

/*
@@ -563,7 +563,7 @@ __update_curr(struct cfs_rq *cfs_rq, str

cfs_rq->load_unacc_exec_time += delta_exec;
if (cfs_rq->load_unacc_exec_time > sysctl_sched_shares_window) {
- update_cfs_load(cfs_rq);
+ update_cfs_load(cfs_rq, 0);
update_cfs_shares(cfs_rq, 0);
}
}
@@ -701,7 +701,22 @@ account_entity_dequeue(struct cfs_rq *cf
}

#if defined CONFIG_SMP && defined CONFIG_FAIR_GROUP_SCHED
-static void update_cfs_load(struct cfs_rq *cfs_rq)
+static void update_cfs_rq_load_contribution(struct cfs_rq *cfs_rq,
+ int global_update)
+{
+ struct task_group *tg = cfs_rq->tg;
+ long load_avg;
+
+ load_avg = div64_u64(cfs_rq->load_avg, cfs_rq->load_period+1);
+ load_avg -= cfs_rq->load_contribution;
+
+ if (global_update || abs(load_avg) > cfs_rq->load_contribution / 8) {
+ atomic_add(load_avg, &tg->load_weight);
+ cfs_rq->load_contribution += load_avg;
+ }
+}
+
+static void update_cfs_load(struct cfs_rq *cfs_rq, int global_update)
{
u64 period = sysctl_sched_shares_window;
u64 now, delta;
@@ -728,6 +743,11 @@ static void update_cfs_load(struct cfs_r
cfs_rq->load_avg += delta * load;
}

+ /* consider updating load contribution on each fold or truncate */
+ if (global_update || cfs_rq->load_period > period
+ || !cfs_rq->load_period)
+ update_cfs_rq_load_contribution(cfs_rq, global_update);
+
while (cfs_rq->load_period > period) {
/*
* Inline assembly required to prevent the compiler
@@ -917,7 +937,7 @@ enqueue_entity(struct cfs_rq *cfs_rq, st
* Update run-time statistics of the 'current'.
*/
update_curr(cfs_rq);
- update_cfs_load(cfs_rq);
+ update_cfs_load(cfs_rq, 0);
update_cfs_shares(cfs_rq_of(se), se->load.weight);
account_entity_enqueue(cfs_rq, se);

@@ -978,7 +998,7 @@ dequeue_entity(struct cfs_rq *cfs_rq, st
if (se != cfs_rq->curr)
__dequeue_entity(cfs_rq, se);
se->on_rq = 0;
- update_cfs_load(cfs_rq);
+ update_cfs_load(cfs_rq, 0);
account_entity_dequeue(cfs_rq, se);
update_min_vruntime(cfs_rq);
update_cfs_shares(cfs_rq_of(se), 0);
@@ -1213,7 +1233,7 @@ enqueue_task_fair(struct rq *rq, struct
for_each_sched_entity(se) {
struct cfs_rq *cfs_rq = cfs_rq_of(se);

- update_cfs_load(cfs_rq);
+ update_cfs_load(cfs_rq, 0);
update_cfs_shares(cfs_rq, 0);
}

@@ -1243,7 +1263,7 @@ static void dequeue_task_fair(struct rq
for_each_sched_entity(se) {
struct cfs_rq *cfs_rq = cfs_rq_of(se);

- update_cfs_load(cfs_rq);
+ update_cfs_load(cfs_rq, 0);
update_cfs_shares(cfs_rq, 0);
}

@@ -2045,7 +2065,6 @@ static int update_shares_cpu(struct task
struct cfs_rq *cfs_rq;
unsigned long flags;
struct rq *rq;
- long load_avg;

if (!tg->se[cpu])
return 0;
@@ -2056,12 +2075,7 @@ static int update_shares_cpu(struct task
raw_spin_lock_irqsave(&rq->lock, flags);

update_rq_clock(rq);
- update_cfs_load(cfs_rq);
-
- load_avg = div64_u64(cfs_rq->load_avg, cfs_rq->load_period+1);
- load_avg -= cfs_rq->load_contribution;
- atomic_add(load_avg, &tg->load_weight);
- cfs_rq->load_contribution += load_avg;
+ update_cfs_load(cfs_rq, 1);

/*
* We need to update shares after updating tg->load_weight in

--