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sched/topology: Add static_key for asymmetric CPU capacity optimizations

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The existing asymmetric CPU capacity code should cause minimal overhead
for others. Putting it behind a static_key, it has been done for SMT
optimizations, would make it easier to extend and improve without
causing harm to others moving forward.

Signed-off-by: Morten Rasmussen <[email protected]>
Signed-off-by: Peter Zijlstra (Intel) <[email protected]>
Cc: Linus Torvalds <[email protected]>
Cc: Peter Zijlstra <[email protected]>
Cc: Thomas Gleixner <[email protected]>
Cc: [email protected]
Cc: [email protected]
Cc: [email protected]
Cc: [email protected]
Link: http://lkml.kernel.org/r/[email protected]
Signed-off-by: Ingo Molnar <[email protected]>
This commit is contained in:
Morten Rasmussen authored and Ingo Molnar committed 2018-09-10 11:05:48 +02:00
1 parent e1799a80a4
commit df054e8445
3 files changed
+12 -1
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kernel/sched/fair.c
+3
View File
@@ -6188,6 +6188,9 @@ static int wake_cap(struct task_struct *p, int cpu, int prev_cpu)
{
long min_cap, max_cap;
if (!static_branch_unlikely(&sched_asym_cpucapacity))
return 0;
min_cap = min(capacity_orig_of(prev_cpu), capacity_orig_of(cpu));
max_cap = cpu_rq(cpu)->rd->max_cpu_capacity;
kernel/sched/sched.h
+1
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@@ -1185,6 +1185,7 @@ DECLARE_PER_CPU(int, sd_llc_id);
DECLARE_PER_CPU(struct sched_domain_shared *, sd_llc_shared);
DECLARE_PER_CPU(struct sched_domain *, sd_numa);
DECLARE_PER_CPU(struct sched_domain *, sd_asym);
extern struct static_key_false sched_asym_cpucapacity;
struct sched_group_capacity {
atomic_t ref;
kernel/sched/topology.c
+8 -1
View File
@@ -398,6 +398,7 @@ DEFINE_PER_CPU(int, sd_llc_id);
DEFINE_PER_CPU(struct sched_domain_shared *, sd_llc_shared);
DEFINE_PER_CPU(struct sched_domain *, sd_numa);
DEFINE_PER_CPU(struct sched_domain *, sd_asym);
DEFINE_STATIC_KEY_FALSE(sched_asym_cpucapacity);
static void update_top_cache_domain(int cpu)
{
@@ -1705,6 +1706,7 @@ build_sched_domains(const struct cpumask *cpu_map, struct sched_domain_attr *att
struct rq *rq = NULL;
int i, ret = -ENOMEM;
struct sched_domain_topology_level *tl_asym;
bool has_asym = false;
alloc_state = __visit_domain_allocation_hell(&d, cpu_map);
if (alloc_state != sa_rootdomain)
@@ -1720,8 +1722,10 @@ build_sched_domains(const struct cpumask *cpu_map, struct sched_domain_attr *att
for_each_sd_topology(tl) {
int dflags = 0;
if (tl == tl_asym)
if (tl == tl_asym) {
dflags |= SD_ASYM_CPUCAPACITY;
has_asym = true;
}
sd = build_sched_domain(tl, cpu_map, attr, sd, dflags, i);
@@ -1773,6 +1777,9 @@ build_sched_domains(const struct cpumask *cpu_map, struct sched_domain_attr *att
}
rcu_read_unlock();
if (has_asym)
static_branch_enable_cpuslocked(&sched_asym_cpucapacity);
if (rq && sched_debug_enabled) {
pr_info("root domain span: %*pbl (max cpu_capacity = %lu)\n",
cpumask_pr_args(cpu_map), rq->rd->max_cpu_capacity);