Stagger load balancing in build_sched_domains
Instead of dealing with the staggering of load balancing
during actual load balancing we just do it once when the sched domains
set up.
Signed-off-by: Christoph Lameter <[email protected]>
Index: linux-2.6.19-rc3/kernel/sched.c
===================================================================
--- linux-2.6.19-rc3.orig/kernel/sched.c 2006-10-27 15:35:40.221104772 -0500
+++ linux-2.6.19-rc3/kernel/sched.c 2006-10-27 15:37:36.526511796 -0500
@@ -2848,17 +2848,10 @@ static void update_load(struct rq *this_
*
* Balancing parameters are set up in arch_init_sched_domains.
*/
-
-/* Don't have all balancing operations going off at once: */
-static inline unsigned long cpu_offset(int cpu)
-{
- return jiffies + cpu * HZ / NR_CPUS;
-}
-
static void
rebalance_tick(int this_cpu, struct rq *this_rq, enum idle_type idle)
{
- unsigned long interval, j = cpu_offset(this_cpu);
+ unsigned long interval;
struct sched_domain *sd;
for_each_domain(this_cpu, sd) {
@@ -2874,7 +2867,7 @@ rebalance_tick(int this_cpu, struct rq *
if (unlikely(!interval))
interval = 1;
- if (j - sd->last_balance >= interval) {
+ if (jiffies - sd->last_balance >= interval) {
if (load_balance(this_cpu, this_rq, sd, idle)) {
/*
* We've pulled tasks over so either we're no
@@ -6327,6 +6320,16 @@ static void init_sched_groups_power(int
}
/*
+ * Calculate jiffies start to use for each cpu. On sched domain
+ * initialization this jiffy value is used to stagger the load balancing
+ * of the cpus so that they do not load balance all at at the same time.
+ */
+static inline unsigned long cpu_offset(int cpu)
+{
+ return jiffies + cpu * HZ / NR_CPUS;
+}
+
+/*
* Build sched domains for a given set of cpus and attach the sched domains
* to the individual cpus
*/
@@ -6382,6 +6385,7 @@ static int build_sched_domains(const cpu
sd->span = *cpu_map;
group = cpu_to_allnodes_group(i, cpu_map);
sd->groups = &sched_group_allnodes[group];
+ sd->last_balance = cpu_offset(i);
p = sd;
} else
p = NULL;
@@ -6390,6 +6394,7 @@ static int build_sched_domains(const cpu
*sd = SD_NODE_INIT;
sd->span = sched_domain_node_span(cpu_to_node(i));
sd->parent = p;
+ sd->last_balance = cpu_offset(i);
if (p)
p->child = sd;
cpus_and(sd->span, sd->span, *cpu_map);
@@ -6401,6 +6406,7 @@ static int build_sched_domains(const cpu
*sd = SD_CPU_INIT;
sd->span = nodemask;
sd->parent = p;
+ sd->last_balance = cpu_offset(i);
if (p)
p->child = sd;
sd->groups = &sched_group_phys[group];
@@ -6413,6 +6419,7 @@ static int build_sched_domains(const cpu
sd->span = cpu_coregroup_map(i);
cpus_and(sd->span, sd->span, *cpu_map);
sd->parent = p;
+ sd->last_balance = cpu_offset(i);
p->child = sd;
sd->groups = &sched_group_core[group];
#endif
@@ -6425,6 +6432,7 @@ static int build_sched_domains(const cpu
sd->span = cpu_sibling_map[i];
cpus_and(sd->span, sd->span, *cpu_map);
sd->parent = p;
+ sd->last_balance = cpu_offset(i);
p->child = sd;
sd->groups = &sched_group_cpus[group];
#endif
-
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