Commit-ID: bbdacdfed2f5fa50a2cc9f500a36e05990a0837d
Gitweb: http://git.kernel.org/tip/bbdacdfed2f5fa50a2cc9f500a36e05990a0837d
Author: Peter Zijlstra <peterz@xxxxxxxxxxxxx>
AuthorDate: Thu, 10 Aug 2017 17:10:26 +0200
Committer: Ingo Molnar <mingo@xxxxxxxxxx>
CommitDate: Fri, 25 Aug 2017 11:12:20 +0200
sched/debug: Optimize sched_domain sysctl generation
Currently we unconditionally destroy all sysctl bits and regenerate
them after we've rebuild the domains (even if that rebuild is a
no-op).
And since we unconditionally (re)build the sysctl for all possible
CPUs, onlining all CPUs gets us O(n^2) time. Instead change this to
only rebuild the bits for CPUs we've actually installed new domains
on.
Reported-by: Ofer Levi(SW) <oferle@xxxxxxxxxxxx>
Signed-off-by: Peter Zijlstra (Intel) <peterz@xxxxxxxxxxxxx>
Cc: Linus Torvalds <torvalds@xxxxxxxxxxxxxxxxxxxx>
Cc: Peter Zijlstra <peterz@xxxxxxxxxxxxx>
Cc: Thomas Gleixner <tglx@xxxxxxxxxxxxx>
Signed-off-by: Ingo Molnar <mingo@xxxxxxxxxx>
---
kernel/sched/debug.c | 68 +++++++++++++++++++++++++++++++++++++++----------
kernel/sched/sched.h | 4 +++
kernel/sched/topology.c | 1 +
3 files changed, 59 insertions(+), 14 deletions(-)
diff --git a/kernel/sched/debug.c b/kernel/sched/debug.c
index cfd84f7..4a23bbc 100644
--- a/kernel/sched/debug.c
+++ b/kernel/sched/debug.c
@@ -327,38 +327,78 @@ static struct ctl_table *sd_alloc_ctl_cpu_table(int cpu)
return table;
}
+static cpumask_var_t sd_sysctl_cpus;
static struct ctl_table_header *sd_sysctl_header;
+
void register_sched_domain_sysctl(void)
{
- int i, cpu_num = num_possible_cpus();
- struct ctl_table *entry = sd_alloc_ctl_entry(cpu_num + 1);
+ static struct ctl_table *cpu_entries;
+ static struct ctl_table **cpu_idx;
char buf[32];
+ int i;
- WARN_ON(sd_ctl_dir[0].child);
- sd_ctl_dir[0].child = entry;
+ if (!cpu_entries) {
+ cpu_entries = sd_alloc_ctl_entry(num_possible_cpus() + 1);
+ if (!cpu_entries)
+ return;
- if (entry == NULL)
- return;
+ WARN_ON(sd_ctl_dir[0].child);
+ sd_ctl_dir[0].child = cpu_entries;
+ }
- for_each_possible_cpu(i) {
- snprintf(buf, 32, "cpu%d", i);
- entry->procname = kstrdup(buf, GFP_KERNEL);
- entry->mode = 0555;
- entry->child = sd_alloc_ctl_cpu_table(i);
- entry++;
+ if (!cpu_idx) {
+ struct ctl_table *e = cpu_entries;
+
+ cpu_idx = kcalloc(nr_cpu_ids, sizeof(struct ctl_table*), GFP_KERNEL);
+ if (!cpu_idx)
+ return;
+
+ /* deal with sparse possible map */
+ for_each_possible_cpu(i) {
+ cpu_idx[i] = e;
+ e++;
+ }
+ }
+
+ if (!cpumask_available(sd_sysctl_cpus)) {
+ if (!alloc_cpumask_var(&sd_sysctl_cpus, GFP_KERNEL))
+ return;
+
+ /* init to possible to not have holes in @cpu_entries */
+ cpumask_copy(sd_sysctl_cpus, cpu_possible_mask);
+ }
+
+ for_each_cpu(i, sd_sysctl_cpus) {
+ struct ctl_table *e = cpu_idx[i];
+
+ if (e->child)
+ sd_free_ctl_entry(&e->child);
+
+ if (!e->procname) {
+ snprintf(buf, 32, "cpu%d", i);
+ e->procname = kstrdup(buf, GFP_KERNEL);
+ }
+ e->mode = 0555;
+ e->child = sd_alloc_ctl_cpu_table(i);
+
+ __cpumask_clear_cpu(i, sd_sysctl_cpus);
}
WARN_ON(sd_sysctl_header);
sd_sysctl_header = register_sysctl_table(sd_ctl_root);
}
+void dirty_sched_domain_sysctl(int cpu)
+{
+ if (cpumask_available(sd_sysctl_cpus))
+ __cpumask_set_cpu(cpu, sd_sysctl_cpus);
+}
+
/* may be called multiple times per register */
void unregister_sched_domain_sysctl(void)
{
unregister_sysctl_table(sd_sysctl_header);
sd_sysctl_header = NULL;
- if (sd_ctl_dir[0].child)
- sd_free_ctl_entry(&sd_ctl_dir[0].child);
}
#endif /* CONFIG_SYSCTL */
#endif /* CONFIG_SMP */
diff --git a/kernel/sched/sched.h b/kernel/sched/sched.h
index eeef1a3..25e5cb1 100644
--- a/kernel/sched/sched.h
+++ b/kernel/sched/sched.h
@@ -1120,11 +1120,15 @@ extern int group_balance_cpu(struct sched_group *sg);
#if defined(CONFIG_SCHED_DEBUG) && defined(CONFIG_SYSCTL)
void register_sched_domain_sysctl(void);
+void dirty_sched_domain_sysctl(int cpu);
void unregister_sched_domain_sysctl(void);
#else
static inline void register_sched_domain_sysctl(void)
{
}
+static inline void dirty_sched_domain_sysctl(int cpu)
+{
+}
static inline void unregister_sched_domain_sysctl(void)
{
}
diff --git a/kernel/sched/topology.c b/kernel/sched/topology.c
index 727daa2..6f7b439 100644
--- a/kernel/sched/topology.c
+++ b/kernel/sched/topology.c
@@ -459,6 +459,7 @@ cpu_attach_domain(struct sched_domain *sd, struct root_domain *rd, int cpu)
rq_attach_root(rq, rd);
tmp = rq->sd;
rcu_assign_pointer(rq->sd, sd);
+ dirty_sched_domain_sysctl(cpu);
destroy_sched_domains(tmp);
update_top_cache_domain(cpu);
--
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