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The Miscellaneous cgroup provides the resource limiting and tracking
mechanism for the scalar resources which cannot be abstracted like the
other cgroup resources. Controller is enabled by the CONFIG_CGROUP_MISC
config option.
A resource can be added to the controller via enum misc_res_type{} in
the include/linux/misc_cgroup.h file and the corresponding name via
misc_res_name[] in the kernel/cgroup/misc.c file. Provider of the
resource must set its capacity prior to using the resource by calling
misc_cg_set_capacity().
Once a capacity is set then the resource usage can be updated using
charge and uncharge APIs. All of the APIs to interact with misc
controller are in include/linux/misc_cgroup.h.
Miscellaneous controller provides 3 interface files. If two misc
resources (res_a and res_b) are registered then:
misc.capacity
A read-only flat-keyed file shown only in the root cgroup. It shows
miscellaneous scalar resources available on the platform along with
their quantities::
$ cat misc.capacity
res_a 50
res_b 10
misc.current
A read-only flat-keyed file shown in the non-root cgroups. It shows
the current usage of the resources in the cgroup and its children::
$ cat misc.current
res_a 3
res_b 0
misc.max
A read-write flat-keyed file shown in the non root cgroups. Allowed
maximum usage of the resources in the cgroup and its children.::
$ cat misc.max
res_a max
res_b 4
Limit can be set by::
# echo res_a 1 > misc.max
Limit can be set to max by::
# echo res_a max > misc.max
Limits can be set more than the capacity value in the misc.capacity
file.
Signed-off-by: Vipin Sharma <vipinsh@google.com>
Reviewed-by: David Rientjes <rientjes@google.com>
Signed-off-by: Tejun Heo <tj@kernel.org>
126 lines
2.8 KiB
C
126 lines
2.8 KiB
C
/* SPDX-License-Identifier: GPL-2.0 */
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/*
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* Miscellaneous cgroup controller.
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*
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* Copyright 2020 Google LLC
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* Author: Vipin Sharma <vipinsh@google.com>
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*/
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#ifndef _MISC_CGROUP_H_
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#define _MISC_CGROUP_H_
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/**
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* Types of misc cgroup entries supported by the host.
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*/
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enum misc_res_type {
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MISC_CG_RES_TYPES
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};
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struct misc_cg;
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#ifdef CONFIG_CGROUP_MISC
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#include <linux/cgroup.h>
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/**
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* struct misc_res: Per cgroup per misc type resource
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* @max: Maximum limit on the resource.
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* @usage: Current usage of the resource.
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* @failed: True if charged failed for the resource in a cgroup.
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*/
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struct misc_res {
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unsigned long max;
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atomic_long_t usage;
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bool failed;
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};
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/**
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* struct misc_cg - Miscellaneous controller's cgroup structure.
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* @css: cgroup subsys state object.
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* @res: Array of misc resources usage in the cgroup.
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*/
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struct misc_cg {
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struct cgroup_subsys_state css;
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struct misc_res res[MISC_CG_RES_TYPES];
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};
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unsigned long misc_cg_res_total_usage(enum misc_res_type type);
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int misc_cg_set_capacity(enum misc_res_type type, unsigned long capacity);
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int misc_cg_try_charge(enum misc_res_type type, struct misc_cg *cg,
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unsigned long amount);
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void misc_cg_uncharge(enum misc_res_type type, struct misc_cg *cg,
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unsigned long amount);
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/**
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* css_misc() - Get misc cgroup from the css.
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* @css: cgroup subsys state object.
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*
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* Context: Any context.
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* Return:
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* * %NULL - If @css is null.
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* * struct misc_cg* - misc cgroup pointer of the passed css.
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*/
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static inline struct misc_cg *css_misc(struct cgroup_subsys_state *css)
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{
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return css ? container_of(css, struct misc_cg, css) : NULL;
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}
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/*
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* get_current_misc_cg() - Find and get the misc cgroup of the current task.
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*
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* Returned cgroup has its ref count increased by 1. Caller must call
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* put_misc_cg() to return the reference.
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*
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* Return: Misc cgroup to which the current task belongs to.
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*/
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static inline struct misc_cg *get_current_misc_cg(void)
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{
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return css_misc(task_get_css(current, misc_cgrp_id));
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}
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/*
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* put_misc_cg() - Put the misc cgroup and reduce its ref count.
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* @cg - cgroup to put.
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*/
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static inline void put_misc_cg(struct misc_cg *cg)
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{
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if (cg)
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css_put(&cg->css);
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}
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#else /* !CONFIG_CGROUP_MISC */
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unsigned long misc_cg_res_total_usage(enum misc_res_type type)
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{
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return 0;
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}
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static inline int misc_cg_set_capacity(enum misc_res_type type,
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unsigned long capacity)
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{
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return 0;
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}
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static inline int misc_cg_try_charge(enum misc_res_type type,
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struct misc_cg *cg,
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unsigned long amount)
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{
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return 0;
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}
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static inline void misc_cg_uncharge(enum misc_res_type type,
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struct misc_cg *cg,
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unsigned long amount)
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{
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}
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static inline struct misc_cg *get_current_misc_cg(void)
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{
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return NULL;
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}
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static inline void put_misc_cg(struct misc_cg *cg)
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{
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}
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#endif /* CONFIG_CGROUP_MISC */
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#endif /* _MISC_CGROUP_H_ */
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