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Message-Id: <1505860632-11275-3-git-send-email-rohit.k.jain@oracle.com>
Date: Tue, 19 Sep 2017 15:37:12 -0700
From: Rohit Jain <rohit.k.jain@...cle.com>
To: linux-kernel@...r.kernel.org, eas-dev@...ts.linaro.org
Cc: peterz@...radead.org, mingo@...hat.com, joelaf@...gle.com
Subject: [PATCH 2/2] sched: Actual changes after adding SCHED_SOFT_AFFINITY to make it work with the scheduler
These are the changes which change the scheduler behavior based on the
cpus_preferred mask. Keep in mind that when the system call changes
cpus_allowed mask, cpus_preferred and cpus_allowed become the same.
Signed-off-by: Rohit Jain <rohit.k.jain@...cle.com>
---
kernel/sched/cpudeadline.c | 4 +-
kernel/sched/cpupri.c | 4 +-
kernel/sched/fair.c | 116 +++++++++++++++++++++++++++++++++------------
3 files changed, 91 insertions(+), 33 deletions(-)
diff --git a/kernel/sched/cpudeadline.c b/kernel/sched/cpudeadline.c
index 8d9562d..32135b9 100644
--- a/kernel/sched/cpudeadline.c
+++ b/kernel/sched/cpudeadline.c
@@ -127,13 +127,13 @@ int cpudl_find(struct cpudl *cp, struct task_struct *p,
const struct sched_dl_entity *dl_se = &p->dl;
if (later_mask &&
- cpumask_and(later_mask, cp->free_cpus, &p->cpus_allowed)) {
+ cpumask_and(later_mask, cp->free_cpus, &p->cpus_preferred)) {
return 1;
} else {
int best_cpu = cpudl_maximum(cp);
WARN_ON(best_cpu != -1 && !cpu_present(best_cpu));
- if (cpumask_test_cpu(best_cpu, &p->cpus_allowed) &&
+ if (cpumask_test_cpu(best_cpu, &p->cpus_preferred) &&
dl_time_before(dl_se->deadline, cp->elements[0].dl)) {
if (later_mask)
cpumask_set_cpu(best_cpu, later_mask);
diff --git a/kernel/sched/cpupri.c b/kernel/sched/cpupri.c
index 2511aba..9641b8d 100644
--- a/kernel/sched/cpupri.c
+++ b/kernel/sched/cpupri.c
@@ -103,11 +103,11 @@ int cpupri_find(struct cpupri *cp, struct task_struct *p,
if (skip)
continue;
- if (cpumask_any_and(&p->cpus_allowed, vec->mask) >= nr_cpu_ids)
+ if (cpumask_any_and(&p->cpus_preferred, vec->mask) >= nr_cpu_ids)
continue;
if (lowest_mask) {
- cpumask_and(lowest_mask, &p->cpus_allowed, vec->mask);
+ cpumask_and(lowest_mask, &p->cpus_preferred, vec->mask);
/*
* We have to ensure that we have at least one bit
diff --git a/kernel/sched/fair.c b/kernel/sched/fair.c
index eca6a57..35e73c7 100644
--- a/kernel/sched/fair.c
+++ b/kernel/sched/fair.c
@@ -5805,7 +5805,7 @@ find_idlest_group(struct sched_domain *sd, struct task_struct *p,
/* Skip over this group if it has no CPUs allowed */
if (!cpumask_intersects(sched_group_span(group),
- &p->cpus_allowed))
+ &p->cpus_preferred))
continue;
local_group = cpumask_test_cpu(this_cpu,
@@ -5925,7 +5925,7 @@ find_idlest_cpu(struct sched_group *group, struct task_struct *p, int this_cpu)
return cpumask_first(sched_group_span(group));
/* Traverse only the allowed CPUs */
- for_each_cpu_and(i, sched_group_span(group), &p->cpus_allowed) {
+ for_each_cpu_and(i, sched_group_span(group), &p->cpus_preferred) {
if (idle_cpu(i)) {
struct rq *rq = cpu_rq(i);
struct cpuidle_state *idle = idle_get_state(rq);
@@ -6011,6 +6011,27 @@ void __update_idle_core(struct rq *rq)
rcu_read_unlock();
}
+static inline int
+scan_cpu_mask_for_idle_cores(struct cpumask *cpus, int target)
+{
+ int core, cpu;
+
+ for_each_cpu_wrap(core, cpus, target) {
+ bool idle = true;
+
+ for_each_cpu(cpu, cpu_smt_mask(core)) {
+ cpumask_clear_cpu(cpu, cpus);
+ if (!idle_cpu(cpu))
+ idle = false;
+ }
+
+ if (idle)
+ return core;
+ }
+
+ return -1;
+}
+
/*
* Scan the entire LLC domain for idle cores; this dynamically switches off if
* there are no idle cores left in the system; tracked through
@@ -6019,7 +6040,8 @@ void __update_idle_core(struct rq *rq)
static int select_idle_core(struct task_struct *p, struct sched_domain *sd, int target)
{
struct cpumask *cpus = this_cpu_cpumask_var_ptr(select_idle_mask);
- int core, cpu;
+ struct cpumask *pcpus = this_cpu_cpumask_var_ptr(select_idle_mask);
+ int core;
if (!static_branch_likely(&sched_smt_present))
return -1;
@@ -6028,20 +6050,21 @@ static int select_idle_core(struct task_struct *p, struct sched_domain *sd, int
return -1;
cpumask_and(cpus, sched_domain_span(sd), &p->cpus_allowed);
+ cpumask_and(pcpus, cpus, &p->cpus_preferred);
+ core = scan_cpu_mask_for_idle_cores(pcpus, target);
- for_each_cpu_wrap(core, cpus, target) {
- bool idle = true;
+ if (core >= 0)
+ return core;
- for_each_cpu(cpu, cpu_smt_mask(core)) {
- cpumask_clear_cpu(cpu, cpus);
- if (!idle_cpu(cpu))
- idle = false;
- }
+ if (cpumask_equal(cpus, pcpus))
+ goto out;
- if (idle)
- return core;
- }
+ cpumask_andnot(cpus, cpus, pcpus);
+ core = scan_cpu_mask_for_idle_cores(cpus, target);
+ if (core >= 0)
+ return core;
+out:
/*
* Failed to find an idle core; stop looking for one.
*/
@@ -6050,24 +6073,40 @@ static int select_idle_core(struct task_struct *p, struct sched_domain *sd, int
return -1;
}
+static inline int
+scan_cpu_mask_for_idle_smt(struct cpumask *cpus, int target)
+{
+ int cpu;
+
+ for_each_cpu(cpu, cpu_smt_mask(target)) {
+ if (!cpumask_test_cpu(cpu, cpus))
+ continue;
+ if (idle_cpu(cpu))
+ return cpu;
+ }
+
+ return -1;
+}
+
/*
* Scan the local SMT mask for idle CPUs.
*/
static int select_idle_smt(struct task_struct *p, struct sched_domain *sd, int target)
{
+ struct cpumask *cpus = &p->cpus_allowed;
int cpu;
if (!static_branch_likely(&sched_smt_present))
return -1;
- for_each_cpu(cpu, cpu_smt_mask(target)) {
- if (!cpumask_test_cpu(cpu, &p->cpus_allowed))
- continue;
- if (idle_cpu(cpu))
- return cpu;
- }
+ cpu = scan_cpu_mask_for_idle_smt(&p->cpus_preferred, target);
- return -1;
+ if (cpu >= 0 || cpumask_equal(&p->cpus_preferred, cpus))
+ return cpu;
+
+ cpumask_andnot(cpus, cpus, &p->cpus_preferred);
+
+ return scan_cpu_mask_for_idle_smt(cpus, target);
}
#else /* CONFIG_SCHED_SMT */
@@ -6084,6 +6123,24 @@ static inline int select_idle_smt(struct task_struct *p, struct sched_domain *sd
#endif /* CONFIG_SCHED_SMT */
+static inline int
+scan_cpu_mask_for_idle_cpu(struct cpumask *cpus, int target,
+ struct sched_domain *sd, int nr)
+{
+ int cpu;
+
+ for_each_cpu_wrap(cpu, sched_domain_span(sd), target) {
+ if (!--nr)
+ return -1;
+ if (!cpumask_test_cpu(cpu, cpus))
+ continue;
+ if (idle_cpu(cpu))
+ break;
+ }
+
+ return cpu;
+}
+
/*
* Scan the LLC domain for idle CPUs; this is dynamically regulated by
* comparing the average scan cost (tracked in sd->avg_scan_cost) against the
@@ -6092,6 +6149,7 @@ static inline int select_idle_smt(struct task_struct *p, struct sched_domain *sd
static int select_idle_cpu(struct task_struct *p, struct sched_domain *sd, int target)
{
struct sched_domain *this_sd;
+ struct cpumask *cpus = this_cpu_cpumask_var_ptr(select_idle_mask);
u64 avg_cost, avg_idle;
u64 time, cost;
s64 delta;
@@ -6121,15 +6179,15 @@ static int select_idle_cpu(struct task_struct *p, struct sched_domain *sd, int t
time = local_clock();
- for_each_cpu_wrap(cpu, sched_domain_span(sd), target) {
- if (!--nr)
- return -1;
- if (!cpumask_test_cpu(cpu, &p->cpus_allowed))
- continue;
- if (idle_cpu(cpu))
- break;
- }
+ cpu = scan_cpu_mask_for_idle_cpu(&p->cpus_preferred, target, sd, nr);
+
+ if (cpu >= 0 || cpumask_equal(&p->cpus_preferred, &p->cpus_allowed))
+ goto out;
+ cpumask_andnot(cpus, &p->cpus_allowed, &p->cpus_preferred);
+
+ cpu = scan_cpu_mask_for_idle_cpu(cpus, target, sd, nr);
+out:
time = local_clock() - time;
cost = this_sd->avg_scan_cost;
delta = (s64)(time - cost) / 8;
@@ -6279,7 +6337,7 @@ select_task_rq_fair(struct task_struct *p, int prev_cpu, int sd_flag, int wake_f
if (sd_flag & SD_BALANCE_WAKE) {
record_wakee(p);
want_affine = !wake_wide(p) && !wake_cap(p, cpu, prev_cpu)
- && cpumask_test_cpu(cpu, &p->cpus_allowed);
+ && cpumask_test_cpu(cpu, &p->cpus_preferred);
}
rcu_read_lock();
--
2.7.4
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