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From: Michael Neuling on 9 Apr 2010 02:30
need_active_balance() gates the asymmetric packing based due to power
save logic, but for packing we don't care.

This marks the type of balanace we are attempting to do perform from
f_b_g() and stops need_active_balance() power save logic gating a
balance in the asymmetric packing case.

Signed-off-by: Michael Neuling <mikey(a)neuling.org>

---

kernel/sched_fair.c | 24 +++++++++++++++++++-----
1 file changed, 19 insertions(+), 5 deletions(-)

Index: linux-2.6-ozlabs/kernel/sched_fair.c
===================================================================
--- linux-2.6-ozlabs.orig/kernel/sched_fair.c
+++ linux-2.6-ozlabs/kernel/sched_fair.c
@@ -91,6 +91,13 @@ const_debug unsigned int sysctl_sched_mi

static const struct sched_class fair_sched_class;

+enum balance_type {
+ BALANCE_NONE = 0,
+ BALANCE_LOAD,
+ BALANCE_POWER,
+ BALANCE_PACKING
+};
+
/**************************************************************
* CFS operations on generic schedulable entities:
*/
@@ -2783,7 +2790,8 @@ static inline void calculate_imbalance(s
static struct sched_group *
find_busiest_group(struct sched_domain *sd, int this_cpu,
unsigned long *imbalance, enum cpu_idle_type idle,
- int *sd_idle, const struct cpumask *cpus, int *balance)
+ int *sd_idle, const struct cpumask *cpus, int *balance,
+ enum balance_type *bt)
{
struct sd_lb_stats sds;

@@ -2808,6 +2816,7 @@ find_busiest_group(struct sched_domain *
if (!(*balance))
goto ret;

+ *bt = BALANCE_PACKING;
if ((idle == CPU_IDLE || idle == CPU_NEWLY_IDLE) &&
check_asym_packing(sd, &sds, this_cpu, imbalance))
return sds.busiest;
@@ -2828,6 +2837,7 @@ find_busiest_group(struct sched_domain *

/* Looks like there is an imbalance. Compute it */
calculate_imbalance(&sds, this_cpu, imbalance);
+ *bt = BALANCE_LOAD;
return sds.busiest;

out_balanced:
@@ -2835,10 +2845,12 @@ out_balanced:
* There is no obvious imbalance. But check if we can do some balancing
* to save power.
*/
+ *bt = BALANCE_POWER;
if (check_power_save_busiest_group(&sds, this_cpu, imbalance))
return sds.busiest;
ret:
*imbalance = 0;
+ *bt = BALANCE_NONE;
return NULL;
}

@@ -2899,9 +2911,10 @@ find_busiest_queue(struct sched_group *g
/* Working cpumask for load_balance and load_balance_newidle. */
static DEFINE_PER_CPU(cpumask_var_t, load_balance_tmpmask);

-static int need_active_balance(struct sched_domain *sd, int sd_idle, int idle)
+static int need_active_balance(struct sched_domain *sd, int sd_idle, int idle,
+ enum balance_type *bt)
{
- if (idle == CPU_NEWLY_IDLE) {
+ if (idle == CPU_NEWLY_IDLE && *bt != BALANCE_PACKING) {
/*
* The only task running in a non-idle cpu can be moved to this
* cpu in an attempt to completely freeup the other CPU
@@ -2946,6 +2959,7 @@ static int load_balance(int this_cpu, st
struct rq *busiest;
unsigned long flags;
struct cpumask *cpus = __get_cpu_var(load_balance_tmpmask);
+ enum balance_type bt;

cpumask_copy(cpus, cpu_active_mask);

@@ -2964,7 +2978,7 @@ static int load_balance(int this_cpu, st
redo:
update_shares(sd);
group = find_busiest_group(sd, this_cpu, &imbalance, idle, &sd_idle,
- cpus, balance);
+ cpus, balance, &bt);

if (*balance == 0)
goto out_balanced;
@@ -3018,7 +3032,7 @@ redo:
schedstat_inc(sd, lb_failed[idle]);
sd->nr_balance_failed++;

- if (need_active_balance(sd, sd_idle, idle)) {
+ if (need_active_balance(sd, sd_idle, idle, &bt)) {
raw_spin_lock_irqsave(&busiest->lock, flags);

/* don't kick the migration_thread, if the curr
--
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