[RFC tg_shares_up improvements - v1 09/12] sched: demand based update_cfs_load()

pjt
2010-10-16T04:54:31Z

[-- Attachment #1: sched-tg-demand_based_update_cfs_load.patch --]
[-- Type: text/plain, Size: 2211 bytes --]

When the system is busy dilation of rq->next_balance makes lb->update_shares()
insufficiently frequent for threads which don't sleep (no dequeue/enqueue
updates). Adjust for this by making demand based updates based on the
accumulation of execution time sufficient to wrap our averaging window.

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

---
kernel/sched.c | 9 ++++++++-
kernel/sched_fair.c | 10 ++++++++++
2 files changed, 18 insertions(+), 1 deletion(-)

Index: kernel/sched.c
===================================================================
--- kernel/sched.c.orig
+++ kernel/sched.c
@@ -355,9 +355,16 @@ struct cfs_rq {
*/
unsigned long h_load;

+ /*
+ * Maintaining per-cpu shares distribution for group scheduling
+ *
+ * load_stamp is the last time we updated the load average
+ * load_last is the last time we updated the load average and saw load
+ * load_unacc_exec_time is currently unaccounted execution time
+ */
u64 load_avg;
u64 load_period;
- u64 load_stamp, load_last;
+ u64 load_stamp, load_last, load_unacc_exec_time;

unsigned long load_contribution;
#endif
Index: kernel/sched_fair.c
===================================================================
--- kernel/sched_fair.c.orig
+++ kernel/sched_fair.c
@@ -538,6 +538,9 @@ 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_shares(struct cfs_rq *cfs_rq, long weight_delta);
+
/*
* Update the current task's runtime statistics. Skip current tasks that
* are not in our scheduling class.
@@ -557,6 +560,12 @@ __update_curr(struct cfs_rq *cfs_rq, str

curr->vruntime += delta_exec_weighted;
update_min_vruntime(cfs_rq);
+
+ 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_shares(cfs_rq, 0);
+ }
}

static void update_curr(struct cfs_rq *cfs_rq)
@@ -712,6 +721,7 @@ static void update_cfs_load(struct cfs_r
}

cfs_rq->load_stamp = now;
+ cfs_rq->load_unacc_exec_time = 0;
cfs_rq->load_period += delta;
if (load) {
cfs_rq->load_last = now;

--