We need to run RT threads in cgroup unified hierarchy, but we can't
since the default rt_bandwidth.rt_runtime of non-root task_group is 0
and we haven't interface to update it.
This patch add RT bandwidth interface "cpu.max.rt" and update the
documentation accordingly.
Signed-off-by: Chengming Zhou <zhouchengming@xxxxxxxxxxxxx>
---
v2:
- minor fix for documentation per Randy's review. Thanks.
---
Documentation/admin-guide/cgroup-v2.rst | 13 +++++++++++
kernel/sched/core.c | 31 +++++++++++++++++++++++++
kernel/sched/rt.c | 2 +-
kernel/sched/sched.h | 1 +
4 files changed, 46 insertions(+), 1 deletion(-)
diff --git a/Documentation/admin-guide/cgroup-v2.rst b/Documentation/admin-guide/cgroup-v2.rst
index 176298f2f4de..3d67366c99e1 100644
--- a/Documentation/admin-guide/cgroup-v2.rst
+++ b/Documentation/admin-guide/cgroup-v2.rst
@@ -1055,6 +1055,19 @@ All time durations are in microseconds.
The burst in the range [0, $MAX].
+ cpu.max.rt
+ A read-write two-value file which exists on all cgroups when
+ CONFIG_RT_GROUP_SCHED is enabled, to control CPU bandwidth for
+ RT threads in the task group.
+
+ The maximum bandwidth limit. It's in the following format::
+
+ $MAX $PERIOD
+
+ which indicates that RT threads in the group may consume up to
+ $MAX in each $PERIOD duration. "max" for $MAX indicates no
+ limit. If only one number is written, $MAX is updated.
+
cpu.pressure
A read-write nested-keyed file.
diff --git a/kernel/sched/core.c b/kernel/sched/core.c
index daadedc78fd9..c16f8cc5de08 100644
--- a/kernel/sched/core.c
+++ b/kernel/sched/core.c
@@ -11047,6 +11047,30 @@ static ssize_t cpu_max_write(struct kernfs_open_file *of,
}
#endif
+#ifdef CONFIG_RT_GROUP_SCHED
+static int cpu_max_rt_show(struct seq_file *sf, void *v)
+{
+ struct task_group *tg = css_tg(seq_css(sf));
+
+ cpu_period_quota_print(sf, sched_group_rt_period(tg), sched_group_rt_runtime(tg));
+ return 0;
+}
+
+static ssize_t cpu_max_rt_write(struct kernfs_open_file *of,
+ char *buf, size_t nbytes, loff_t off)
+{
+ struct task_group *tg = css_tg(of_css(of));
+ u64 period = sched_group_rt_period(tg);
+ u64 runtime;
+ int ret;
+
+ ret = cpu_period_quota_parse(buf, &period, &runtime);
+ if (!ret)
+ ret = tg_set_rt_bandwidth(tg, period, runtime);
+ return ret ?: nbytes;
+}
+#endif
+
static struct cftype cpu_files[] = {
#ifdef CONFIG_FAIR_GROUP_SCHED
{
@@ -11082,6 +11106,13 @@ static struct cftype cpu_files[] = {
.write_u64 = cpu_cfs_burst_write_u64,
},
#endif
+#ifdef CONFIG_RT_GROUP_SCHED
+ {
+ .name = "max.rt",
+ .seq_show = cpu_max_rt_show,
+ .write = cpu_max_rt_write,
+ },
+#endif
#ifdef CONFIG_UCLAMP_TASK_GROUP
{
.name = "uclamp.min",
diff --git a/kernel/sched/rt.c b/kernel/sched/rt.c
index 8c9ed9664840..319ce586446f 100644
--- a/kernel/sched/rt.c
+++ b/kernel/sched/rt.c
@@ -2819,7 +2819,7 @@ static int __rt_schedulable(struct task_group *tg, u64 period, u64 runtime)
return ret;
}
-static int tg_set_rt_bandwidth(struct task_group *tg,
+int tg_set_rt_bandwidth(struct task_group *tg,
u64 rt_period, u64 rt_runtime)
{
int i, err = 0;
diff --git a/kernel/sched/sched.h b/kernel/sched/sched.h
index 7b19a72408b1..317480d535b0 100644
--- a/kernel/sched/sched.h
+++ b/kernel/sched/sched.h
@@ -486,6 +486,7 @@ extern int alloc_rt_sched_group(struct task_group *tg, struct task_group *parent
extern void init_tg_rt_entry(struct task_group *tg, struct rt_rq *rt_rq,
struct sched_rt_entity *rt_se, int cpu,
struct sched_rt_entity *parent);
+extern int tg_set_rt_bandwidth(struct task_group *tg, u64 rt_period, u64 rt_runtime);
extern int sched_group_set_rt_runtime(struct task_group *tg, long rt_runtime_us);
extern int sched_group_set_rt_period(struct task_group *tg, u64 rt_period_us);
extern long sched_group_rt_runtime(struct task_group *tg);
--
2.36.1
