[PATCH 3/5] sched: Introduce CONFIG_GROUP_SCHED_WEIGHT

Tejun Heo
2024-08-26T22:58:30Z

sched_ext will soon add cgroup cpu.weigh support. The cgroup interface code
is currently gated behind CONFIG_FAIR_GROUP_SCHED. As the fair class and/or
SCX may implement the feature, put the interface code behind the new
CONFIG_CGROUP_SCHED_WEIGHT which is selected by CONFIG_FAIR_GROUP_SCHED.
This allows either sched class to enable the itnerface code without ading
more complex CONFIG tests.

When !CONFIG_FAIR_GROUP_SCHED, a dummy version of sched_group_set_shares()
is added to support later CONFIG_CGROUP_SCHED_WEIGHT &&
!CONFIG_FAIR_GROUP_SCHED builds.

No functional changes.

Signed-off-by: Tejun Heo <tj@kernel.org>
---
init/Kconfig | 4 ++++
kernel/sched/core.c | 14 +++++++-------
kernel/sched/sched.h | 4 +++-
3 files changed, 14 insertions(+), 8 deletions(-)

diff --git a/init/Kconfig b/init/Kconfig
index a465ea9525bd..84332d3594d0 100644
--- a/init/Kconfig
+++ b/init/Kconfig
@@ -1024,9 +1024,13 @@ menuconfig CGROUP_SCHED
tasks.

if CGROUP_SCHED
+config GROUP_SCHED_WEIGHT
+ def_bool n
+
config FAIR_GROUP_SCHED
bool "Group scheduling for SCHED_OTHER"
depends on CGROUP_SCHED
+ select GROUP_SCHED_WEIGHT
default CGROUP_SCHED

config CFS_BANDWIDTH
diff --git a/kernel/sched/core.c b/kernel/sched/core.c
index 4de62872a346..5cdf7b6a40f7 100644
--- a/kernel/sched/core.c
+++ b/kernel/sched/core.c
@@ -9208,7 +9208,7 @@ static int cpu_uclamp_max_show(struct seq_file *sf, void *v)
}
#endif /* CONFIG_UCLAMP_TASK_GROUP */

-#ifdef CONFIG_FAIR_GROUP_SCHED
+#ifdef CONFIG_GROUP_SCHED_WEIGHT
static unsigned long tg_weight(struct task_group *tg)
{
return scale_load_down(tg->shares);
@@ -9227,6 +9227,7 @@ static u64 cpu_shares_read_u64(struct cgroup_subsys_state *css,
{
return tg_weight(css_tg(css));
}
+#endif /* CONFIG_GROUP_SCHED_WEIGHT */

#ifdef CONFIG_CFS_BANDWIDTH
static DEFINE_MUTEX(cfs_constraints_mutex);
@@ -9572,7 +9573,6 @@ static int cpu_cfs_local_stat_show(struct seq_file *sf, void *v)
return 0;
}
#endif /* CONFIG_CFS_BANDWIDTH */
-#endif /* CONFIG_FAIR_GROUP_SCHED */

#ifdef CONFIG_RT_GROUP_SCHED
static int cpu_rt_runtime_write(struct cgroup_subsys_state *css,
@@ -9600,7 +9600,7 @@ static u64 cpu_rt_period_read_uint(struct cgroup_subsys_state *css,
}
#endif /* CONFIG_RT_GROUP_SCHED */

-#ifdef CONFIG_FAIR_GROUP_SCHED
+#ifdef CONFIG_GROUP_SCHED_WEIGHT
static s64 cpu_idle_read_s64(struct cgroup_subsys_state *css,
struct cftype *cft)
{
@@ -9615,7 +9615,7 @@ static int cpu_idle_write_s64(struct cgroup_subsys_state *css,
#endif

static struct cftype cpu_legacy_files[] = {
-#ifdef CONFIG_FAIR_GROUP_SCHED
+#ifdef CONFIG_GROUP_SCHED_WEIGHT
{
.name = "shares",
.read_u64 = cpu_shares_read_u64,
@@ -9725,7 +9725,7 @@ static int cpu_local_stat_show(struct seq_file *sf,
return 0;
}

-#ifdef CONFIG_FAIR_GROUP_SCHED
+#ifdef CONFIG_GROUP_SCHED_WEIGHT

static u64 cpu_weight_read_u64(struct cgroup_subsys_state *css,
struct cftype *cft)
@@ -9779,7 +9779,7 @@ static int cpu_weight_nice_write_s64(struct cgroup_subsys_state *css,

return sched_group_set_shares(css_tg(css), scale_load(weight));
}
-#endif
+#endif /* CONFIG_GROUP_SCHED_WEIGHT */

static void __maybe_unused cpu_period_quota_print(struct seq_file *sf,
long period, long quota)
@@ -9839,7 +9839,7 @@ static ssize_t cpu_max_write(struct kernfs_open_file *of,
#endif

static struct cftype cpu_files[] = {
-#ifdef CONFIG_FAIR_GROUP_SCHED
+#ifdef CONFIG_GROUP_SCHED_WEIGHT
{
.name = "weight",
.flags = CFTYPE_NOT_ON_ROOT,
diff --git a/kernel/sched/sched.h b/kernel/sched/sched.h
index 07333c545ddc..b471fcd5950c 100644
--- a/kernel/sched/sched.h
+++ b/kernel/sched/sched.h
@@ -484,7 +484,7 @@ struct task_group {

};

-#ifdef CONFIG_FAIR_GROUP_SCHED
+#ifdef CONFIG_GROUP_SCHED_WEIGHT
#define ROOT_TASK_GROUP_LOAD NICE_0_LOAD

/*
@@ -576,6 +576,8 @@ extern void set_task_rq_fair(struct sched_entity *se,
static inline void set_task_rq_fair(struct sched_entity *se,
struct cfs_rq *prev, struct cfs_rq *next) { }
#endif /* CONFIG_SMP */
+#else /* !CONFIG_FAIR_GROUP_SCHED */
+static inline int sched_group_set_shares(struct task_group *tg, unsigned long shares) { return 0; }
#endif /* CONFIG_FAIR_GROUP_SCHED */

#else /* CONFIG_CGROUP_SCHED */
--
2.46.0