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sched_ext: Add support for cgroup bandwidth control interface

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From 077814f57f8acce13f91dc34bbd2b7e4911fbf25 Mon Sep 17 00:00:00 2001
From: Tejun Heo <tj@kernel.org>
Date: Fri, 13 Jun 2025 15:06:47 -1000

- Add CONFIG_GROUP_SCHED_BANDWIDTH which is selected by both
  CONFIG_CFS_BANDWIDTH and EXT_GROUP_SCHED.

- Put bandwidth control interface files for both cgroup v1 and v2 under
  CONFIG_GROUP_SCHED_BANDWIDTH.

- Update tg_bandwidth() to fetch configuration parameters from fair if
  CONFIG_CFS_BANDWIDTH, SCX otherwise.

- Update tg_set_bandwidth() to update the parameters for both fair and SCX.

- Add bandwidth control parameters to struct scx_cgroup_init_args.

- Add sched_ext_ops.cgroup_set_bandwidth() which is invoked on bandwidth
  control parameter updates.

- Update scx_qmap and maximal selftest to test the new feature.

Signed-off-by: Tejun Heo <tj@kernel.org>
This commit is contained in:
Tejun Heo 2025-06-13 15:34:22 -10:00
parent 6e6558a6bc
commit ddceadce63
8 changed files with 127 additions and 10 deletions
Show stats Download patch file Download diff file Expand all files Collapse all files

3
include/linux/sched/ext.h
View file

@ -219,6 +219,9 @@ struct scx_task_group {
#ifdef CONFIG_EXT_GROUP_SCHED
u32 flags; /* SCX_TG_* */
u32 weight;
u64 bw_period_us;
u64 bw_quota_us;
u64 bw_burst_us;
#endif
};

5
init/Kconfig
View file

@ -1065,6 +1065,9 @@ if CGROUP_SCHED
config GROUP_SCHED_WEIGHT
def_bool n
config GROUP_SCHED_BANDWIDTH
def_bool n
config FAIR_GROUP_SCHED
bool "Group scheduling for SCHED_OTHER"
depends on CGROUP_SCHED
@ -1074,6 +1077,7 @@ config FAIR_GROUP_SCHED
config CFS_BANDWIDTH
bool "CPU bandwidth provisioning for FAIR_GROUP_SCHED"
depends on FAIR_GROUP_SCHED
select GROUP_SCHED_BANDWIDTH
default n
help
This option allows users to define CPU bandwidth rates (limits) for
@ -1108,6 +1112,7 @@ config EXT_GROUP_SCHED
bool
depends on SCHED_CLASS_EXT && CGROUP_SCHED
select GROUP_SCHED_WEIGHT
select GROUP_SCHED_BANDWIDTH
default y
endif #CGROUP_SCHED

29
kernel/sched/core.c
View file

@ -9545,7 +9545,9 @@ static int cpu_cfs_local_stat_show(struct seq_file *sf, void *v)
return 0;
}
#endif /* CONFIG_CFS_BANDWIDTH */
#ifdef CONFIG_GROUP_SCHED_BANDWIDTH
const u64 max_bw_quota_period_us = 1 * USEC_PER_SEC; /* 1s */
static const u64 min_bw_quota_period_us = 1 * USEC_PER_MSEC; /* 1ms */
/* More than 203 days if BW_SHIFT equals 20. */
@ -9554,12 +9556,21 @@ static const u64 max_bw_runtime_us = MAX_BW;
static void tg_bandwidth(struct task_group *tg,
u64 *period_us_p, u64 *quota_us_p, u64 *burst_us_p)
{
#ifdef CONFIG_CFS_BANDWIDTH
if (period_us_p)
*period_us_p = tg_get_cfs_period(tg);
if (quota_us_p)
*quota_us_p = tg_get_cfs_quota(tg);
if (burst_us_p)
*burst_us_p = tg_get_cfs_burst(tg);
#else /* !CONFIG_CFS_BANDWIDTH */
if (period_us_p)
*period_us_p = tg->scx.bw_period_us;
if (quota_us_p)
*quota_us_p = tg->scx.bw_quota_us;
if (burst_us_p)
*burst_us_p = tg->scx.bw_burst_us;
#endif /* CONFIG_CFS_BANDWIDTH */
}
static u64 cpu_period_read_u64(struct cgroup_subsys_state *css,
@ -9575,6 +9586,7 @@ static int tg_set_bandwidth(struct task_group *tg,
u64 period_us, u64 quota_us, u64 burst_us)
{
const u64 max_usec = U64_MAX / NSEC_PER_USEC;
int ret = 0;
if (tg == &root_task_group)
return -EINVAL;
@ -9612,7 +9624,12 @@ static int tg_set_bandwidth(struct task_group *tg,
burst_us + quota_us > max_bw_runtime_us))
return -EINVAL;
return tg_set_cfs_bandwidth(tg, period_us, quota_us, burst_us);
#ifdef CONFIG_CFS_BANDWIDTH
ret = tg_set_cfs_bandwidth(tg, period_us, quota_us, burst_us);
#endif /* CONFIG_CFS_BANDWIDTH */
if (!ret)
scx_group_set_bandwidth(tg, period_us, quota_us, burst_us);
return ret;
}
static s64 cpu_quota_read_s64(struct cgroup_subsys_state *css,
@ -9665,7 +9682,7 @@ static int cpu_burst_write_u64(struct cgroup_subsys_state *css,
tg_bandwidth(tg, &period_us, &quota_us, NULL);
return tg_set_bandwidth(tg, period_us, quota_us, burst_us);
}
#endif /* CONFIG_CFS_BANDWIDTH */
#endif /* CONFIG_GROUP_SCHED_BANDWIDTH */
#ifdef CONFIG_RT_GROUP_SCHED
static int cpu_rt_runtime_write(struct cgroup_subsys_state *css,
@ -9725,7 +9742,7 @@ static struct cftype cpu_legacy_files[] = {
.write_s64 = cpu_idle_write_s64,
},
#endif
#ifdef CONFIG_CFS_BANDWIDTH
#ifdef CONFIG_GROUP_SCHED_BANDWIDTH
{
.name = "cfs_period_us",
.read_u64 = cpu_period_read_u64,
@ -9741,6 +9758,8 @@ static struct cftype cpu_legacy_files[] = {
.read_u64 = cpu_burst_read_u64,
.write_u64 = cpu_burst_write_u64,
},
#endif
#ifdef CONFIG_CFS_BANDWIDTH
{
.name = "stat",
.seq_show = cpu_cfs_stat_show,
@ -9954,7 +9973,7 @@ static int __maybe_unused cpu_period_quota_parse(char *buf, u64 *period_us_p,
return 0;
}
#ifdef CONFIG_CFS_BANDWIDTH
#ifdef CONFIG_GROUP_SCHED_BANDWIDTH
static int cpu_max_show(struct seq_file *sf, void *v)
{
struct task_group *tg = css_tg(seq_css(sf));
@ -10001,7 +10020,7 @@ static struct cftype cpu_files[] = {
.write_s64 = cpu_idle_write_s64,
},
#endif
#ifdef CONFIG_CFS_BANDWIDTH
#ifdef CONFIG_GROUP_SCHED_BANDWIDTH
{
.name = "max",
.flags = CFTYPE_NOT_ON_ROOT,

66
kernel/sched/ext.c
View file

@ -203,6 +203,11 @@ struct scx_exit_task_args {
struct scx_cgroup_init_args {
/* the weight of the cgroup [1..10000] */
u32 weight;
/* bandwidth control parameters from cpu.max and cpu.max.burst */
u64 bw_period_us;
u64 bw_quota_us;
u64 bw_burst_us;
};
enum scx_cpu_preempt_reason {
@ -664,9 +669,31 @@ struct sched_ext_ops {
* @cgrp: cgroup whose weight is being updated
* @weight: new weight [1..10000]
*
* Update @tg's weight to @weight.
* Update @cgrp's weight to @weight.
*/
void (*cgroup_set_weight)(struct cgroup *cgrp, u32 weight);
/**
* @cgroup_set_bandwidth: A cgroup's bandwidth is being changed
* @cgrp: cgroup whose bandwidth is being updated
* @period_us: bandwidth control period
* @quota_us: bandwidth control quota
* @burst_us: bandwidth control burst
*
* Update @cgrp's bandwidth control parameters. This is from the cpu.max
* cgroup interface.
*
* @quota_us / @period_us determines the CPU bandwidth @cgrp is entitled
* to. For example, if @period_us is 1_000_000 and @quota_us is
* 2_500_000. @cgrp is entitled to 2.5 CPUs. @burst_us can be
* interpreted in the same fashion and specifies how much @cgrp can
* burst temporarily. The specific control mechanism and thus the
* interpretation of @period_us and burstiness is upto to the BPF
* scheduler.
*/
void (*cgroup_set_bandwidth)(struct cgroup *cgrp,
u64 period_us, u64 quota_us, u64 burst_us);
#endif /* CONFIG_EXT_GROUP_SCHED */
/*
@ -4059,6 +4086,8 @@ static bool scx_cgroup_enabled;
void scx_tg_init(struct task_group *tg)
{
tg->scx.weight = CGROUP_WEIGHT_DFL;
tg->scx.bw_period_us = default_bw_period_us();
tg->scx.bw_quota_us = RUNTIME_INF;
}
int scx_tg_online(struct task_group *tg)
@ -4073,7 +4102,10 @@ int scx_tg_online(struct task_group *tg)
if (scx_cgroup_enabled) {
if (SCX_HAS_OP(sch, cgroup_init)) {
struct scx_cgroup_init_args args =
{ .weight = tg->scx.weight };
{ .weight = tg->scx.weight,
.bw_period_us = tg->scx.bw_period_us,
.bw_quota_us = tg->scx.bw_quota_us,
.bw_burst_us = tg->scx.bw_burst_us };
ret = SCX_CALL_OP_RET(sch, SCX_KF_UNLOCKED, cgroup_init,
NULL, tg->css.cgroup, &args);
@ -4225,6 +4257,27 @@ void scx_group_set_idle(struct task_group *tg, bool idle)
/* TODO: Implement ops->cgroup_set_idle() */
}
void scx_group_set_bandwidth(struct task_group *tg,
u64 period_us, u64 quota_us, u64 burst_us)
{
struct scx_sched *sch = scx_root;
percpu_down_read(&scx_cgroup_rwsem);
if (scx_cgroup_enabled && SCX_HAS_OP(sch, cgroup_set_bandwidth) &&
(tg->scx.bw_period_us != period_us ||
tg->scx.bw_quota_us != quota_us ||
tg->scx.bw_burst_us != burst_us))
SCX_CALL_OP(sch, SCX_KF_UNLOCKED, cgroup_set_bandwidth, NULL,
tg_cgrp(tg), period_us, quota_us, burst_us);
tg->scx.bw_period_us = period_us;
tg->scx.bw_quota_us = quota_us;
tg->scx.bw_burst_us = burst_us;
percpu_up_read(&scx_cgroup_rwsem);
}
static void scx_cgroup_lock(void)
{
percpu_down_write(&scx_cgroup_rwsem);
@ -4400,7 +4453,12 @@ static int scx_cgroup_init(struct scx_sched *sch)
rcu_read_lock();
css_for_each_descendant_pre(css, &root_task_group.css) {
struct task_group *tg = css_tg(css);
struct scx_cgroup_init_args args = { .weight = tg->scx.weight };
struct scx_cgroup_init_args args = {
.weight = tg->scx.weight,
.bw_period_us = tg->scx.bw_period_us,
.bw_quota_us = tg->scx.bw_quota_us,
.bw_burst_us = tg->scx.bw_burst_us,
};
if ((tg->scx.flags &
(SCX_TG_ONLINE | SCX_TG_INITED)) != SCX_TG_ONLINE)
@ -5902,6 +5960,7 @@ static s32 sched_ext_ops__cgroup_prep_move(struct task_struct *p, struct cgroup
static void sched_ext_ops__cgroup_move(struct task_struct *p, struct cgroup *from, struct cgroup *to) {}
static void sched_ext_ops__cgroup_cancel_move(struct task_struct *p, struct cgroup *from, struct cgroup *to) {}
static void sched_ext_ops__cgroup_set_weight(struct cgroup *cgrp, u32 weight) {}
static void sched_ext_ops__cgroup_set_bandwidth(struct cgroup *cgrp, u64 period_us, u64 quota_us, u64 burst_us) {}
#endif
static void sched_ext_ops__cpu_online(s32 cpu) {}
static void sched_ext_ops__cpu_offline(s32 cpu) {}
@ -5939,6 +5998,7 @@ static struct sched_ext_ops __bpf_ops_sched_ext_ops = {
.cgroup_move = sched_ext_ops__cgroup_move,
.cgroup_cancel_move = sched_ext_ops__cgroup_cancel_move,
.cgroup_set_weight = sched_ext_ops__cgroup_set_weight,
.cgroup_set_bandwidth = sched_ext_ops__cgroup_set_bandwidth,
#endif
.cpu_online = sched_ext_ops__cpu_online,
.cpu_offline = sched_ext_ops__cpu_offline,

2
kernel/sched/ext.h
View file

@ -104,6 +104,7 @@ void scx_cgroup_finish_attach(void);
void scx_cgroup_cancel_attach(struct cgroup_taskset *tset);
void scx_group_set_weight(struct task_group *tg, unsigned long cgrp_weight);
void scx_group_set_idle(struct task_group *tg, bool idle);
void scx_group_set_bandwidth(struct task_group *tg, u64 period_us, u64 quota_us, u64 burst_us);
#else /* CONFIG_EXT_GROUP_SCHED */
static inline void scx_tg_init(struct task_group *tg) {}
static inline int scx_tg_online(struct task_group *tg) { return 0; }
@ -114,5 +115,6 @@ static inline void scx_cgroup_finish_attach(void) {}
static inline void scx_cgroup_cancel_attach(struct cgroup_taskset *tset) {}
static inline void scx_group_set_weight(struct task_group *tg, unsigned long cgrp_weight) {}
static inline void scx_group_set_idle(struct task_group *tg, bool idle) {}
static inline void scx_group_set_bandwidth(struct task_group *tg, u64 period_us, u64 quota_us, u64 burst_us) {}
#endif /* CONFIG_EXT_GROUP_SCHED */
#endif /* CONFIG_CGROUP_SCHED */

4
kernel/sched/sched.h
View file

@ -402,7 +402,7 @@ static inline bool dl_server_active(struct sched_dl_entity *dl_se)
extern struct list_head task_groups;
#ifdef CONFIG_CFS_BANDWIDTH
#ifdef CONFIG_GROUP_SCHED_BANDWIDTH
extern const u64 max_bw_quota_period_us;
/*
@ -413,7 +413,7 @@ static inline u64 default_bw_period_us(void)
{
return 100000ULL;
}
#endif /* CONFIG_CFS_BANDWIDTH */
#endif /* CONFIG_GROUP_SCHED_BANDWIDTH */
struct cfs_bandwidth {
#ifdef CONFIG_CFS_BANDWIDTH

23
tools/sched_ext/scx_qmap.bpf.c
View file

@ -615,6 +615,26 @@ void BPF_STRUCT_OPS(qmap_dump_task, struct scx_dump_ctx *dctx, struct task_struc
taskc->force_local, taskc->core_sched_seq);
}
s32 BPF_STRUCT_OPS(qmap_cgroup_init, struct cgroup *cgrp, struct scx_cgroup_init_args *args)
{
bpf_printk("CGRP INIT %llu weight=%u period=%lu quota=%ld burst=%lu",
cgrp->kn->id, args->weight, args->bw_period_us,
args->bw_quota_us, args->bw_burst_us);
return 0;
}
void BPF_STRUCT_OPS(qmap_cgroup_set_weight, struct cgroup *cgrp, u32 weight)
{
bpf_printk("CGRP SET %llu weight=%u", cgrp->kn->id, weight);
}
void BPF_STRUCT_OPS(qmap_cgroup_set_bandwidth, struct cgroup *cgrp,
u64 period_us, u64 quota_us, u64 burst_us)
{
bpf_printk("CGRP SET %llu period=%lu quota=%ld burst=%lu", cgrp->kn->id,
period_us, quota_us, burst_us);
}
/*
* Print out the online and possible CPU map using bpf_printk() as a
* demonstration of using the cpumask kfuncs and ops.cpu_on/offline().
@ -840,6 +860,9 @@ SCX_OPS_DEFINE(qmap_ops,
.dump = (void *)qmap_dump,
.dump_cpu = (void *)qmap_dump_cpu,
.dump_task = (void *)qmap_dump_task,
.cgroup_init = (void *)qmap_cgroup_init,
.cgroup_set_weight = (void *)qmap_cgroup_set_weight,
.cgroup_set_bandwidth = (void *)qmap_cgroup_set_bandwidth,
.cpu_online = (void *)qmap_cpu_online,
.cpu_offline = (void *)qmap_cpu_offline,
.init = (void *)qmap_init,

5
tools/testing/selftests/sched_ext/maximal.bpf.c
View file

@ -123,6 +123,10 @@ void BPF_STRUCT_OPS(maximal_cgroup_cancel_move, struct task_struct *p,
void BPF_STRUCT_OPS(maximal_cgroup_set_weight, struct cgroup *cgrp, u32 weight)
{}
void BPF_STRUCT_OPS(maximal_cgroup_set_bandwidth, struct cgroup *cgrp,
u64 period_us, u64 quota_us, u64 burst_us)
{}
s32 BPF_STRUCT_OPS_SLEEPABLE(maximal_init)
{
return scx_bpf_create_dsq(DSQ_ID, -1);
@ -160,6 +164,7 @@ struct sched_ext_ops maximal_ops = {
.cgroup_move = (void *) maximal_cgroup_move,
.cgroup_cancel_move = (void *) maximal_cgroup_cancel_move,
.cgroup_set_weight = (void *) maximal_cgroup_set_weight,
.cgroup_set_bandwidth = (void *) maximal_cgroup_set_bandwidth,
.init = (void *) maximal_init,
.exit = (void *) maximal_exit,
.name = "maximal",