[tip:sched/core] sched: Fix SD_POWERSAVING_BALANCE|SD_PREFER_LOCAL vs SD_WAKE_AFFINE

tip-bot for Peter Zijlstra
2009-09-17T08:55:24Z

Commit-ID: 29cd8bae396583a2ee9a3340db8c5102acf9f6fd
Gitweb: http://git.kernel.org/tip/29cd8bae396583a2ee9a3340db8c5102acf9f6fd
Author: Peter Zijlstra <a.p.zijlstra@chello.nl>
AuthorDate: Thu, 17 Sep 2009 09:01:14 +0200
Committer: Ingo Molnar <mingo@elte.hu>
CommitDate: Thu, 17 Sep 2009 10:40:31 +0200

sched: Fix SD_POWERSAVING_BALANCE|SD_PREFER_LOCAL vs SD_WAKE_AFFINE

The SD_POWERSAVING_BALANCE|SD_PREFER_LOCAL code can break out of
the domain iteration early, making us miss the SD_WAKE_AFFINE bits.

Fix this by continuing iteration until there is no need for a
larger domain.

This also cleans up the cgroup stuff a bit, but not having two
update_shares() invocations.

Signed-off-by: Peter Zijlstra <a.p.zijlstra@chello.nl>
LKML-Reference: <new-submission>
Signed-off-by: Ingo Molnar <mingo@elte.hu>

---
kernel/sched_fair.c | 42 +++++++++++++++++++++++++++---------------
1 files changed, 27 insertions(+), 15 deletions(-)

diff --git a/kernel/sched_fair.c b/kernel/sched_fair.c
index ffee827..10d218a 100644
--- a/kernel/sched_fair.c
+++ b/kernel/sched_fair.c
@@ -1333,11 +1333,12 @@ find_idlest_cpu(struct sched_group *group, struct task_struct *p, int this_cpu)
*/
static int select_task_rq_fair(struct task_struct *p, int sd_flag, int wake_flags)
{
- struct sched_domain *tmp, *shares = NULL, *sd = NULL;
+ struct sched_domain *tmp, *affine_sd = NULL, *sd = NULL;
int cpu = smp_processor_id();
int prev_cpu = task_cpu(p);
int new_cpu = cpu;
int want_affine = 0;
+ int want_sd = 1;
int sync = wake_flags & WF_SYNC;

if (sd_flag & SD_BALANCE_WAKE) {
@@ -1369,33 +1370,44 @@ static int select_task_rq_fair(struct task_struct *p, int sd_flag, int wake_flag
nr_running /= 2;

if (nr_running < capacity)
- break;
+ want_sd = 0;
}

if (want_affine && (tmp->flags & SD_WAKE_AFFINE) &&
cpumask_test_cpu(prev_cpu, sched_domain_span(tmp))) {

- if (sched_feat(LB_SHARES_UPDATE)) {
- update_shares(tmp);
- shares = tmp;
- }
-
- if (wake_affine(tmp, p, sync)) {
- new_cpu = cpu;
- goto out;
- }
-
+ affine_sd = tmp;
want_affine = 0;
}

+ if (!want_sd && !want_affine)
+ break;
+
if (!(tmp->flags & sd_flag))
continue;

- sd = tmp;
+ if (want_sd)
+ sd = tmp;
+ }
+
+ if (sched_feat(LB_SHARES_UPDATE)) {
+ /*
+ * Pick the largest domain to update shares over
+ */
+ tmp = sd;
+ if (affine_sd && (!tmp ||
+ cpumask_weight(sched_domain_span(affine_sd)) >
+ cpumask_weight(sched_domain_span(sd))))
+ tmp = affine_sd;
+
+ if (tmp)
+ update_shares(tmp);
}

- if (sd && sd != shares && sched_feat(LB_SHARES_UPDATE))
- update_shares(sd);
+ if (affine_sd && wake_affine(affine_sd, p, sync)) {
+ new_cpu = cpu;
+ goto out;
+ }

while (sd) {
int load_idx = sd->forkexec_idx;