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Subject[tip:sched/balancing] sched: Simple helper functions for find_busiest_group()
Commit-ID:  67bb6c036d1fc3d332c8527a36a546e3e72e822c
Gitweb: http://git.kernel.org/tip/67bb6c036d1fc3d332c8527a36a546e3e72e822c
Author: Gautham R Shenoy <ego@in.ibm.com>
AuthorDate: Wed, 25 Mar 2009 14:43:35 +0530
Committer: Ingo Molnar <mingo@elte.hu>
CommitDate: Wed, 25 Mar 2009 10:30:44 +0100

sched: Simple helper functions for find_busiest_group()

Impact: cleanup

Currently the load idx calculation code is in find_busiest_group().
Move that to a static inline helper function.

Similary, to find the first cpu of a sched_group we use
cpumask_first(sched_group_cpus(group))

Use a helper to that. It improves readability in some cases.

Signed-off-by: Gautham R Shenoy <ego@in.ibm.com>
Acked-by: Peter Zijlstra <a.p.zijlstra@chello.nl>
Cc: Suresh Siddha <suresh.b.siddha@intel.com>
Cc: "Balbir Singh" <balbir@in.ibm.com>
Cc: Nick Piggin <nickpiggin@yahoo.com.au>
Cc: "Dhaval Giani" <dhaval@linux.vnet.ibm.com>
Cc: Bharata B Rao <bharata@linux.vnet.ibm.com>
Cc: "Vaidyanathan Srinivasan" <svaidy@linux.vnet.ibm.com>
LKML-Reference: <20090325091335.13992.55424.stgit@sofia.in.ibm.com>
Signed-off-by: Ingo Molnar <mingo@elte.hu>


---
kernel/sched.c | 55 +++++++++++++++++++++++++++++++++++++++++++------------
1 files changed, 43 insertions(+), 12 deletions(-)

diff --git a/kernel/sched.c b/kernel/sched.c
index 7b389c7..6aec1e7 100644
--- a/kernel/sched.c
+++ b/kernel/sched.c
@@ -3189,6 +3189,43 @@ static int move_one_task(struct rq *this_rq, int this_cpu, struct rq *busiest,

return 0;
}
+/********** Helpers for find_busiest_group ************************/
+
+/**
+ * group_first_cpu - Returns the first cpu in the cpumask of a sched_group.
+ * @group: The group whose first cpu is to be returned.
+ */
+static inline unsigned int group_first_cpu(struct sched_group *group)
+{
+ return cpumask_first(sched_group_cpus(group));
+}
+
+/**
+ * get_sd_load_idx - Obtain the load index for a given sched domain.
+ * @sd: The sched_domain whose load_idx is to be obtained.
+ * @idle: The Idle status of the CPU for whose sd load_icx is obtained.
+ */
+static inline int get_sd_load_idx(struct sched_domain *sd,
+ enum cpu_idle_type idle)
+{
+ int load_idx;
+
+ switch (idle) {
+ case CPU_NOT_IDLE:
+ load_idx = sd->busy_idx;
+ break;
+
+ case CPU_NEWLY_IDLE:
+ load_idx = sd->newidle_idx;
+ break;
+ default:
+ load_idx = sd->idle_idx;
+ break;
+ }
+
+ return load_idx;
+}
+/******* find_busiest_group() helpers end here *********************/

/*
* find_busiest_group finds and returns the busiest CPU group within the
@@ -3217,12 +3254,7 @@ find_busiest_group(struct sched_domain *sd, int this_cpu,
busiest_load_per_task = busiest_nr_running = 0;
this_load_per_task = this_nr_running = 0;

- if (idle == CPU_NOT_IDLE)
- load_idx = sd->busy_idx;
- else if (idle == CPU_NEWLY_IDLE)
- load_idx = sd->newidle_idx;
- else
- load_idx = sd->idle_idx;
+ load_idx = get_sd_load_idx(sd, idle);

do {
unsigned long load, group_capacity, max_cpu_load, min_cpu_load;
@@ -3238,7 +3270,7 @@ find_busiest_group(struct sched_domain *sd, int this_cpu,
sched_group_cpus(group));

if (local_group)
- balance_cpu = cpumask_first(sched_group_cpus(group));
+ balance_cpu = group_first_cpu(group);

/* Tally up the load of all CPUs in the group */
sum_weighted_load = sum_nr_running = avg_load = 0;
@@ -3359,8 +3391,7 @@ find_busiest_group(struct sched_domain *sd, int this_cpu,
*/
if ((sum_nr_running < min_nr_running) ||
(sum_nr_running == min_nr_running &&
- cpumask_first(sched_group_cpus(group)) >
- cpumask_first(sched_group_cpus(group_min)))) {
+ group_first_cpu(group) > group_first_cpu(group_min))) {
group_min = group;
min_nr_running = sum_nr_running;
min_load_per_task = sum_weighted_load /
@@ -3375,8 +3406,8 @@ find_busiest_group(struct sched_domain *sd, int this_cpu,
if (sum_nr_running <= group_capacity - 1) {
if (sum_nr_running > leader_nr_running ||
(sum_nr_running == leader_nr_running &&
- cpumask_first(sched_group_cpus(group)) <
- cpumask_first(sched_group_cpus(group_leader)))) {
+ group_first_cpu(group) <
+ group_first_cpu(group_leader))) {
group_leader = group;
leader_nr_running = sum_nr_running;
}
@@ -3504,7 +3535,7 @@ out_balanced:
*imbalance = min_load_per_task;
if (sched_mc_power_savings >= POWERSAVINGS_BALANCE_WAKEUP) {
cpu_rq(this_cpu)->rd->sched_mc_preferred_wakeup_cpu =
- cpumask_first(sched_group_cpus(group_leader));
+ group_first_cpu(group_leader);
}
return group_min;
}

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