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-rw-r--r--Documentation/admin-guide/kernel-parameters.txt9
-rw-r--r--include/linux/cgroup-defs.h1
-rw-r--r--include/linux/cgroup.h7
-rw-r--r--kernel/cgroup/cgroup.c48
-rw-r--r--kernel/sched/psi.c30
5 files changed, 80 insertions, 15 deletions
diff --git a/Documentation/admin-guide/kernel-parameters.txt b/Documentation/admin-guide/kernel-parameters.txt
index cb89dbdedc46..653c62142f07 100644
--- a/Documentation/admin-guide/kernel-parameters.txt
+++ b/Documentation/admin-guide/kernel-parameters.txt
@@ -497,16 +497,21 @@
ccw_timeout_log [S390]
See Documentation/s390/common_io.rst for details.
- cgroup_disable= [KNL] Disable a particular controller
- Format: {name of the controller(s) to disable}
+ cgroup_disable= [KNL] Disable a particular controller or optional feature
+ Format: {name of the controller(s) or feature(s) to disable}
The effects of cgroup_disable=foo are:
- foo isn't auto-mounted if you mount all cgroups in
a single hierarchy
- foo isn't visible as an individually mountable
subsystem
+ - if foo is an optional feature then the feature is
+ disabled and corresponding cgroup files are not
+ created
{Currently only "memory" controller deal with this and
cut the overhead, others just disable the usage. So
only cgroup_disable=memory is actually worthy}
+ Specifying "pressure" disables per-cgroup pressure
+ stall information accounting feature
cgroup_no_v1= [KNL] Disable cgroup controllers and named hierarchies in v1
Format: { { controller | "all" | "named" }
diff --git a/include/linux/cgroup-defs.h b/include/linux/cgroup-defs.h
index 1a1f3e8faceb..e1c705fdfa7c 100644
--- a/include/linux/cgroup-defs.h
+++ b/include/linux/cgroup-defs.h
@@ -113,6 +113,7 @@ enum {
CFTYPE_NO_PREFIX = (1 << 3), /* (DON'T USE FOR NEW FILES) no subsys prefix */
CFTYPE_WORLD_WRITABLE = (1 << 4), /* (DON'T USE FOR NEW FILES) S_IWUGO */
CFTYPE_DEBUG = (1 << 5), /* create when cgroup_debug */
+ CFTYPE_PRESSURE = (1 << 6), /* only if pressure feature is enabled */
/* internal flags, do not use outside cgroup core proper */
__CFTYPE_ONLY_ON_DFL = (1 << 16), /* only on default hierarchy */
diff --git a/include/linux/cgroup.h b/include/linux/cgroup.h
index 9047fa853dd3..2cc237e3e8b3 100644
--- a/include/linux/cgroup.h
+++ b/include/linux/cgroup.h
@@ -676,6 +676,8 @@ static inline struct psi_group *cgroup_psi(struct cgroup *cgrp)
return &cgrp->psi;
}
+bool cgroup_psi_enabled(void);
+
static inline void cgroup_init_kthreadd(void)
{
/*
@@ -735,6 +737,11 @@ static inline struct psi_group *cgroup_psi(struct cgroup *cgrp)
return NULL;
}
+static inline bool cgroup_psi_enabled(void)
+{
+ return false;
+}
+
static inline bool task_under_cgroup_hierarchy(struct task_struct *task,
struct cgroup *ancestor)
{
diff --git a/kernel/cgroup/cgroup.c b/kernel/cgroup/cgroup.c
index 74e3cc801615..e13a37f4acab 100644
--- a/kernel/cgroup/cgroup.c
+++ b/kernel/cgroup/cgroup.c
@@ -209,6 +209,22 @@ struct cgroup_namespace init_cgroup_ns = {
static struct file_system_type cgroup2_fs_type;
static struct cftype cgroup_base_files[];
+/* cgroup optional features */
+enum cgroup_opt_features {
+#ifdef CONFIG_PSI
+ OPT_FEATURE_PRESSURE,
+#endif
+ OPT_FEATURE_COUNT
+};
+
+static const char *cgroup_opt_feature_names[OPT_FEATURE_COUNT] = {
+#ifdef CONFIG_PSI
+ "pressure",
+#endif
+};
+
+static u16 cgroup_feature_disable_mask __read_mostly;
+
static int cgroup_apply_control(struct cgroup *cgrp);
static void cgroup_finalize_control(struct cgroup *cgrp, int ret);
static void css_task_iter_skip(struct css_task_iter *it,
@@ -3631,6 +3647,18 @@ static void cgroup_pressure_release(struct kernfs_open_file *of)
{
psi_trigger_replace(&of->priv, NULL);
}
+
+bool cgroup_psi_enabled(void)
+{
+ return (cgroup_feature_disable_mask & (1 << OPT_FEATURE_PRESSURE)) == 0;
+}
+
+#else /* CONFIG_PSI */
+bool cgroup_psi_enabled(void)
+{
+ return false;
+}
+
#endif /* CONFIG_PSI */
static int cgroup_freeze_show(struct seq_file *seq, void *v)
@@ -3955,6 +3983,8 @@ static int cgroup_addrm_files(struct cgroup_subsys_state *css,
restart:
for (cft = cfts; cft != cft_end && cft->name[0] != '\0'; cft++) {
/* does cft->flags tell us to skip this file on @cgrp? */
+ if ((cft->flags & CFTYPE_PRESSURE) && !cgroup_psi_enabled())
+ continue;
if ((cft->flags & __CFTYPE_ONLY_ON_DFL) && !cgroup_on_dfl(cgrp))
continue;
if ((cft->flags & __CFTYPE_NOT_ON_DFL) && cgroup_on_dfl(cgrp))
@@ -4032,6 +4062,9 @@ static int cgroup_init_cftypes(struct cgroup_subsys *ss, struct cftype *cfts)
WARN_ON(cft->ss || cft->kf_ops);
+ if ((cft->flags & CFTYPE_PRESSURE) && !cgroup_psi_enabled())
+ continue;
+
if (cft->seq_start)
kf_ops = &cgroup_kf_ops;
else
@@ -4945,6 +4978,7 @@ static struct cftype cgroup_base_files[] = {
#ifdef CONFIG_PSI
{
.name = "io.pressure",
+ .flags = CFTYPE_PRESSURE,
.seq_show = cgroup_io_pressure_show,
.write = cgroup_io_pressure_write,
.poll = cgroup_pressure_poll,
@@ -4952,6 +4986,7 @@ static struct cftype cgroup_base_files[] = {
},
{
.name = "memory.pressure",
+ .flags = CFTYPE_PRESSURE,
.seq_show = cgroup_memory_pressure_show,
.write = cgroup_memory_pressure_write,
.poll = cgroup_pressure_poll,
@@ -4959,6 +4994,7 @@ static struct cftype cgroup_base_files[] = {
},
{
.name = "cpu.pressure",
+ .flags = CFTYPE_PRESSURE,
.seq_show = cgroup_cpu_pressure_show,
.write = cgroup_cpu_pressure_write,
.poll = cgroup_pressure_poll,
@@ -6313,6 +6349,15 @@ static int __init cgroup_disable(char *str)
pr_info("Disabling %s control group subsystem\n",
ss->name);
}
+
+ for (i = 0; i < OPT_FEATURE_COUNT; i++) {
+ if (strcmp(token, cgroup_opt_feature_names[i]))
+ continue;
+ cgroup_feature_disable_mask |= 1 << i;
+ pr_info("Disabling %s control group feature\n",
+ cgroup_opt_feature_names[i]);
+ break;
+ }
}
return 1;
}
@@ -6611,6 +6656,9 @@ static ssize_t show_delegatable_files(struct cftype *files, char *buf,
if (!(cft->flags & CFTYPE_NS_DELEGATABLE))
continue;
+ if ((cft->flags & CFTYPE_PRESSURE) && !cgroup_psi_enabled())
+ continue;
+
if (prefix)
ret += snprintf(buf + ret, size - ret, "%s.", prefix);
diff --git a/kernel/sched/psi.c b/kernel/sched/psi.c
index cc25a3cff41f..b773cae4c24b 100644
--- a/kernel/sched/psi.c
+++ b/kernel/sched/psi.c
@@ -148,6 +148,7 @@
static int psi_bug __read_mostly;
DEFINE_STATIC_KEY_FALSE(psi_disabled);
+DEFINE_STATIC_KEY_TRUE(psi_cgroups_enabled);
#ifdef CONFIG_PSI_DEFAULT_DISABLED
static bool psi_enable;
@@ -211,6 +212,9 @@ void __init psi_init(void)
return;
}
+ if (!cgroup_psi_enabled())
+ static_branch_disable(&psi_cgroups_enabled);
+
psi_period = jiffies_to_nsecs(PSI_FREQ);
group_init(&psi_system);
}
@@ -744,23 +748,23 @@ static void psi_group_change(struct psi_group *group, int cpu,
static struct psi_group *iterate_groups(struct task_struct *task, void **iter)
{
+ if (*iter == &psi_system)
+ return NULL;
+
#ifdef CONFIG_CGROUPS
- struct cgroup *cgroup = NULL;
+ if (static_branch_likely(&psi_cgroups_enabled)) {
+ struct cgroup *cgroup = NULL;
- if (!*iter)
- cgroup = task->cgroups->dfl_cgrp;
- else if (*iter == &psi_system)
- return NULL;
- else
- cgroup = cgroup_parent(*iter);
+ if (!*iter)
+ cgroup = task->cgroups->dfl_cgrp;
+ else
+ cgroup = cgroup_parent(*iter);
- if (cgroup && cgroup_parent(cgroup)) {
- *iter = cgroup;
- return cgroup_psi(cgroup);
+ if (cgroup && cgroup_parent(cgroup)) {
+ *iter = cgroup;
+ return cgroup_psi(cgroup);
+ }
}
-#else
- if (*iter)
- return NULL;
#endif
*iter = &psi_system;
return &psi_system;