Re: [PATCHv4 01/12] sched: Add static_key for asymmetric cpu capacity optimizations
On Tue, Jul 31, 2018 at 12:59:16PM +0200, Peter Zijlstra wrote: > > Combined with that SD_ASYM.. rework I ended up with the below. > > Holler if you want it changed :-) Looks good to me. Thanks, Morten
Re: [PATCHv4 01/12] sched: Add static_key for asymmetric cpu capacity optimizations
On Tue, Jul 31, 2018 at 12:59:16PM +0200, Peter Zijlstra wrote: > > Combined with that SD_ASYM.. rework I ended up with the below. > > Holler if you want it changed :-) Looks good to me. Thanks, Morten
Re: [PATCHv4 01/12] sched: Add static_key for asymmetric cpu capacity optimizations
Combined with that SD_ASYM.. rework I ended up with the below.
Holler if you want it changed :-)
---
Subject: sched: Add static_key for asymmetric cpu capacity optimizations
From: Morten Rasmussen
Date: Wed, 4 Jul 2018 11:17:39 +0100
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.
cc: Ingo Molnar
cc: Peter Zijlstra
Cc: valentin.schnei...@arm.com
Cc: mi...@redhat.com
Cc: vincent.guit...@linaro.org
Cc: dietmar.eggem...@arm.com
Cc: gaku.inami...@renesas.com
Signed-off-by: Morten Rasmussen
Signed-off-by: Peter Zijlstra (Intel)
Link:
http://lkml.kernel.org/r/1530699470-29808-2-git-send-email-morten.rasmus...@arm.com
---
kernel/sched/fair.c |3 +++
kernel/sched/sched.h|1 +
kernel/sched/topology.c |9 -
3 files changed, 12 insertions(+), 1 deletion(-)
--- a/kernel/sched/fair.c
+++ b/kernel/sched/fair.c
@@ -6186,6 +6186,9 @@ static int wake_cap(struct task_struct *
{
long min_cap, max_cap;
+ if (!static_branch_unlikely(_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;
--- a/kernel/sched/sched.h
+++ b/kernel/sched/sched.h
@@ -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_tref;
--- a/kernel/sched/topology.c
+++ b/kernel/sched/topology.c
@@ -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)
{
@@ -1708,6 +1709,7 @@ build_sched_domains(const struct cpumask
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(, cpu_map);
if (alloc_state != sa_rootdomain)
@@ -1723,8 +1725,10 @@ build_sched_domains(const struct cpumask
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);
@@ -1776,6 +1780,9 @@ build_sched_domains(const struct cpumask
}
rcu_read_unlock();
+ if (has_asym)
+ static_branch_enable_cpuslocked(_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);
Re: [PATCHv4 01/12] sched: Add static_key for asymmetric cpu capacity optimizations
Combined with that SD_ASYM.. rework I ended up with the below.
Holler if you want it changed :-)
---
Subject: sched: Add static_key for asymmetric cpu capacity optimizations
From: Morten Rasmussen
Date: Wed, 4 Jul 2018 11:17:39 +0100
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.
cc: Ingo Molnar
cc: Peter Zijlstra
Cc: valentin.schnei...@arm.com
Cc: mi...@redhat.com
Cc: vincent.guit...@linaro.org
Cc: dietmar.eggem...@arm.com
Cc: gaku.inami...@renesas.com
Signed-off-by: Morten Rasmussen
Signed-off-by: Peter Zijlstra (Intel)
Link:
http://lkml.kernel.org/r/1530699470-29808-2-git-send-email-morten.rasmus...@arm.com
---
kernel/sched/fair.c |3 +++
kernel/sched/sched.h|1 +
kernel/sched/topology.c |9 -
3 files changed, 12 insertions(+), 1 deletion(-)
--- a/kernel/sched/fair.c
+++ b/kernel/sched/fair.c
@@ -6186,6 +6186,9 @@ static int wake_cap(struct task_struct *
{
long min_cap, max_cap;
+ if (!static_branch_unlikely(_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;
--- a/kernel/sched/sched.h
+++ b/kernel/sched/sched.h
@@ -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_tref;
--- a/kernel/sched/topology.c
+++ b/kernel/sched/topology.c
@@ -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)
{
@@ -1708,6 +1709,7 @@ build_sched_domains(const struct cpumask
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(, cpu_map);
if (alloc_state != sa_rootdomain)
@@ -1723,8 +1725,10 @@ build_sched_domains(const struct cpumask
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);
@@ -1776,6 +1780,9 @@ build_sched_domains(const struct cpumask
}
rcu_read_unlock();
+ if (has_asym)
+ static_branch_enable_cpuslocked(_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);
