2.1. Design
-The core of the design is a counter called the res_counter. The res_counter
-tracks the current memory usage and limit of the group of processes associated
-with the controller. Each cgroup has a memory controller specific data
-structure (mem_cgroup) associated with it.
+The core of the design is a counter called the page_counter. The
+page_counter tracks the current memory usage and limit of the group of
+processes associated with the controller. Each cgroup has a memory controller
+specific data structure (mem_cgroup) associated with it.
2.2. Accounting
+--------------------+
- | mem_cgroup |
- | (res_counter) |
+ | mem_cgroup |
+ | (page_counter) |
+--------------------+
/ ^ \
/ | \
0. Configuration
a. Enable CONFIG_CGROUPS
-b. Enable CONFIG_RESOURCE_COUNTERS
-c. Enable CONFIG_MEMCG
-d. Enable CONFIG_MEMCG_SWAP (to use swap extension)
+b. Enable CONFIG_MEMCG
+c. Enable CONFIG_MEMCG_SWAP (to use swap extension)
d. Enable CONFIG_MEMCG_KMEM (to use kmem extension)
1. Prepare the cgroups (see cgroups.txt, Why are cgroups needed?)
+++ /dev/null
-
- The Resource Counter
-
-The resource counter, declared at include/linux/res_counter.h,
-is supposed to facilitate the resource management by controllers
-by providing common stuff for accounting.
-
-This "stuff" includes the res_counter structure and routines
-to work with it.
-
-
-
-1. Crucial parts of the res_counter structure
-
- a. unsigned long long usage
-
- The usage value shows the amount of a resource that is consumed
- by a group at a given time. The units of measurement should be
- determined by the controller that uses this counter. E.g. it can
- be bytes, items or any other unit the controller operates on.
-
- b. unsigned long long max_usage
-
- The maximal value of the usage over time.
-
- This value is useful when gathering statistical information about
- the particular group, as it shows the actual resource requirements
- for a particular group, not just some usage snapshot.
-
- c. unsigned long long limit
-
- The maximal allowed amount of resource to consume by the group. In
- case the group requests for more resources, so that the usage value
- would exceed the limit, the resource allocation is rejected (see
- the next section).
-
- d. unsigned long long failcnt
-
- The failcnt stands for "failures counter". This is the number of
- resource allocation attempts that failed.
-
- c. spinlock_t lock
-
- Protects changes of the above values.
-
-
-
-2. Basic accounting routines
-
- a. void res_counter_init(struct res_counter *rc,
- struct res_counter *rc_parent)
-
- Initializes the resource counter. As usual, should be the first
- routine called for a new counter.
-
- The struct res_counter *parent can be used to define a hierarchical
- child -> parent relationship directly in the res_counter structure,
- NULL can be used to define no relationship.
-
- c. int res_counter_charge(struct res_counter *rc, unsigned long val,
- struct res_counter **limit_fail_at)
-
- When a resource is about to be allocated it has to be accounted
- with the appropriate resource counter (controller should determine
- which one to use on its own). This operation is called "charging".
-
- This is not very important which operation - resource allocation
- or charging - is performed first, but
- * if the allocation is performed first, this may create a
- temporary resource over-usage by the time resource counter is
- charged;
- * if the charging is performed first, then it should be uncharged
- on error path (if the one is called).
-
- If the charging fails and a hierarchical dependency exists, the
- limit_fail_at parameter is set to the particular res_counter element
- where the charging failed.
-
- d. u64 res_counter_uncharge(struct res_counter *rc, unsigned long val)
-
- When a resource is released (freed) it should be de-accounted
- from the resource counter it was accounted to. This is called
- "uncharging". The return value of this function indicate the amount
- of charges still present in the counter.
-
- The _locked routines imply that the res_counter->lock is taken.
-
- e. u64 res_counter_uncharge_until
- (struct res_counter *rc, struct res_counter *top,
- unsigned long val)
-
- Almost same as res_counter_uncharge() but propagation of uncharge
- stops when rc == top. This is useful when kill a res_counter in
- child cgroup.
-
- 2.1 Other accounting routines
-
- There are more routines that may help you with common needs, like
- checking whether the limit is reached or resetting the max_usage
- value. They are all declared in include/linux/res_counter.h.
-
-
-
-3. Analyzing the resource counter registrations
-
- a. If the failcnt value constantly grows, this means that the counter's
- limit is too tight. Either the group is misbehaving and consumes too
- many resources, or the configuration is not suitable for the group
- and the limit should be increased.
-
- b. The max_usage value can be used to quickly tune the group. One may
- set the limits to maximal values and either load the container with
- a common pattern or leave one for a while. After this the max_usage
- value shows the amount of memory the container would require during
- its common activity.
-
- Setting the limit a bit above this value gives a pretty good
- configuration that works in most of the cases.
-
- c. If the max_usage is much less than the limit, but the failcnt value
- is growing, then the group tries to allocate a big chunk of resource
- at once.
-
- d. If the max_usage is much less than the limit, but the failcnt value
- is 0, then this group is given too high limit, that it does not
- require. It is better to lower the limit a bit leaving more resource
- for other groups.
-
-
-
-4. Communication with the control groups subsystem (cgroups)
-
-All the resource controllers that are using cgroups and resource counters
-should provide files (in the cgroup filesystem) to work with the resource
-counter fields. They are recommended to adhere to the following rules:
-
- a. File names
-
- Field name File name
- ---------------------------------------------------
- usage usage_in_<unit_of_measurement>
- max_usage max_usage_in_<unit_of_measurement>
- limit limit_in_<unit_of_measurement>
- failcnt failcnt
- lock no file :)
-
- b. Reading from file should show the corresponding field value in the
- appropriate format.
-
- c. Writing to file
-
- Field Expected behavior
- ----------------------------------
- usage prohibited
- max_usage reset to usage
- limit set the limit
- failcnt reset to zero
-
-
-
-5. Usage example
-
- a. Declare a task group (take a look at cgroups subsystem for this) and
- fold a res_counter into it
-
- struct my_group {
- struct res_counter res;
-
- <other fields>
- }
-
- b. Put hooks in resource allocation/release paths
-
- int alloc_something(...)
- {
- if (res_counter_charge(res_counter_ptr, amount) < 0)
- return -ENOMEM;
-
- <allocate the resource and return to the caller>
- }
-
- void release_something(...)
- {
- res_counter_uncharge(res_counter_ptr, amount);
-
- <release the resource>
- }
-
- In order to keep the usage value self-consistent, both the
- "res_counter_ptr" and the "amount" in release_something() should be
- the same as they were in the alloc_something() when the releasing
- resource was allocated.
-
- c. Provide the way to read res_counter values and set them (the cgroups
- still can help with it).
-
- c. Compile and run :)
+++ /dev/null
-#ifndef __RES_COUNTER_H__
-#define __RES_COUNTER_H__
-
-/*
- * Resource Counters
- * Contain common data types and routines for resource accounting
- *
- * Copyright 2007 OpenVZ SWsoft Inc
- *
- * Author: Pavel Emelianov <xemul@openvz.org>
- *
- * See Documentation/cgroups/resource_counter.txt for more
- * info about what this counter is.
- */
-
-#include <linux/spinlock.h>
-#include <linux/errno.h>
-
-/*
- * The core object. the cgroup that wishes to account for some
- * resource may include this counter into its structures and use
- * the helpers described beyond
- */
-
-struct res_counter {
- /*
- * the current resource consumption level
- */
- unsigned long long usage;
- /*
- * the maximal value of the usage from the counter creation
- */
- unsigned long long max_usage;
- /*
- * the limit that usage cannot exceed
- */
- unsigned long long limit;
- /*
- * the limit that usage can be exceed
- */
- unsigned long long soft_limit;
- /*
- * the number of unsuccessful attempts to consume the resource
- */
- unsigned long long failcnt;
- /*
- * the lock to protect all of the above.
- * the routines below consider this to be IRQ-safe
- */
- spinlock_t lock;
- /*
- * Parent counter, used for hierarchial resource accounting
- */
- struct res_counter *parent;
-};
-
-#define RES_COUNTER_MAX ULLONG_MAX
-
-/**
- * Helpers to interact with userspace
- * res_counter_read_u64() - returns the value of the specified member.
- * res_counter_read/_write - put/get the specified fields from the
- * res_counter struct to/from the user
- *
- * @counter: the counter in question
- * @member: the field to work with (see RES_xxx below)
- * @buf: the buffer to opeate on,...
- * @nbytes: its size...
- * @pos: and the offset.
- */
-
-u64 res_counter_read_u64(struct res_counter *counter, int member);
-
-ssize_t res_counter_read(struct res_counter *counter, int member,
- const char __user *buf, size_t nbytes, loff_t *pos,
- int (*read_strategy)(unsigned long long val, char *s));
-
-int res_counter_memparse_write_strategy(const char *buf,
- unsigned long long *res);
-
-/*
- * the field descriptors. one for each member of res_counter
- */
-
-enum {
- RES_USAGE,
- RES_MAX_USAGE,
- RES_LIMIT,
- RES_FAILCNT,
- RES_SOFT_LIMIT,
-};
-
-/*
- * helpers for accounting
- */
-
-void res_counter_init(struct res_counter *counter, struct res_counter *parent);
-
-/*
- * charge - try to consume more resource.
- *
- * @counter: the counter
- * @val: the amount of the resource. each controller defines its own
- * units, e.g. numbers, bytes, Kbytes, etc
- *
- * returns 0 on success and <0 if the counter->usage will exceed the
- * counter->limit
- *
- * charge_nofail works the same, except that it charges the resource
- * counter unconditionally, and returns < 0 if the after the current
- * charge we are over limit.
- */
-
-int __must_check res_counter_charge(struct res_counter *counter,
- unsigned long val, struct res_counter **limit_fail_at);
-int res_counter_charge_nofail(struct res_counter *counter,
- unsigned long val, struct res_counter **limit_fail_at);
-
-/*
- * uncharge - tell that some portion of the resource is released
- *
- * @counter: the counter
- * @val: the amount of the resource
- *
- * these calls check for usage underflow and show a warning on the console
- *
- * returns the total charges still present in @counter.
- */
-
-u64 res_counter_uncharge(struct res_counter *counter, unsigned long val);
-
-u64 res_counter_uncharge_until(struct res_counter *counter,
- struct res_counter *top,
- unsigned long val);
-/**
- * res_counter_margin - calculate chargeable space of a counter
- * @cnt: the counter
- *
- * Returns the difference between the hard limit and the current usage
- * of resource counter @cnt.
- */
-static inline unsigned long long res_counter_margin(struct res_counter *cnt)
-{
- unsigned long long margin;
- unsigned long flags;
-
- spin_lock_irqsave(&cnt->lock, flags);
- if (cnt->limit > cnt->usage)
- margin = cnt->limit - cnt->usage;
- else
- margin = 0;
- spin_unlock_irqrestore(&cnt->lock, flags);
- return margin;
-}
-
-/**
- * Get the difference between the usage and the soft limit
- * @cnt: The counter
- *
- * Returns 0 if usage is less than or equal to soft limit
- * The difference between usage and soft limit, otherwise.
- */
-static inline unsigned long long
-res_counter_soft_limit_excess(struct res_counter *cnt)
-{
- unsigned long long excess;
- unsigned long flags;
-
- spin_lock_irqsave(&cnt->lock, flags);
- if (cnt->usage <= cnt->soft_limit)
- excess = 0;
- else
- excess = cnt->usage - cnt->soft_limit;
- spin_unlock_irqrestore(&cnt->lock, flags);
- return excess;
-}
-
-static inline void res_counter_reset_max(struct res_counter *cnt)
-{
- unsigned long flags;
-
- spin_lock_irqsave(&cnt->lock, flags);
- cnt->max_usage = cnt->usage;
- spin_unlock_irqrestore(&cnt->lock, flags);
-}
-
-static inline void res_counter_reset_failcnt(struct res_counter *cnt)
-{
- unsigned long flags;
-
- spin_lock_irqsave(&cnt->lock, flags);
- cnt->failcnt = 0;
- spin_unlock_irqrestore(&cnt->lock, flags);
-}
-
-static inline int res_counter_set_limit(struct res_counter *cnt,
- unsigned long long limit)
-{
- unsigned long flags;
- int ret = -EBUSY;
-
- spin_lock_irqsave(&cnt->lock, flags);
- if (cnt->usage <= limit) {
- cnt->limit = limit;
- ret = 0;
- }
- spin_unlock_irqrestore(&cnt->lock, flags);
- return ret;
-}
-
-static inline int
-res_counter_set_soft_limit(struct res_counter *cnt,
- unsigned long long soft_limit)
-{
- unsigned long flags;
-
- spin_lock_irqsave(&cnt->lock, flags);
- cnt->soft_limit = soft_limit;
- spin_unlock_irqrestore(&cnt->lock, flags);
- return 0;
-}
-
-#endif
Provides a simple Resource Controller for monitoring the
total CPU consumed by the tasks in a cgroup.
-config RESOURCE_COUNTERS
- bool "Resource counters"
- help
- This option enables controller independent resource accounting
- infrastructure that works with cgroups.
-
config PAGE_COUNTER
bool
obj-$(CONFIG_USER_NS) += user_namespace.o
obj-$(CONFIG_PID_NS) += pid_namespace.o
obj-$(CONFIG_IKCONFIG) += configs.o
-obj-$(CONFIG_RESOURCE_COUNTERS) += res_counter.o
obj-$(CONFIG_SMP) += stop_machine.o
obj-$(CONFIG_KPROBES_SANITY_TEST) += test_kprobes.o
obj-$(CONFIG_AUDIT) += audit.o auditfilter.o
+++ /dev/null
-/*
- * resource cgroups
- *
- * Copyright 2007 OpenVZ SWsoft Inc
- *
- * Author: Pavel Emelianov <xemul@openvz.org>
- *
- */
-
-#include <linux/types.h>
-#include <linux/parser.h>
-#include <linux/fs.h>
-#include <linux/res_counter.h>
-#include <linux/uaccess.h>
-#include <linux/mm.h>
-
-void res_counter_init(struct res_counter *counter, struct res_counter *parent)
-{
- spin_lock_init(&counter->lock);
- counter->limit = RES_COUNTER_MAX;
- counter->soft_limit = RES_COUNTER_MAX;
- counter->parent = parent;
-}
-
-static u64 res_counter_uncharge_locked(struct res_counter *counter,
- unsigned long val)
-{
- if (WARN_ON(counter->usage < val))
- val = counter->usage;
-
- counter->usage -= val;
- return counter->usage;
-}
-
-static int res_counter_charge_locked(struct res_counter *counter,
- unsigned long val, bool force)
-{
- int ret = 0;
-
- if (counter->usage + val > counter->limit) {
- counter->failcnt++;
- ret = -ENOMEM;
- if (!force)
- return ret;
- }
-
- counter->usage += val;
- if (counter->usage > counter->max_usage)
- counter->max_usage = counter->usage;
- return ret;
-}
-
-static int __res_counter_charge(struct res_counter *counter, unsigned long val,
- struct res_counter **limit_fail_at, bool force)
-{
- int ret, r;
- unsigned long flags;
- struct res_counter *c, *u;
-
- r = ret = 0;
- *limit_fail_at = NULL;
- local_irq_save(flags);
- for (c = counter; c != NULL; c = c->parent) {
- spin_lock(&c->lock);
- r = res_counter_charge_locked(c, val, force);
- spin_unlock(&c->lock);
- if (r < 0 && !ret) {
- ret = r;
- *limit_fail_at = c;
- if (!force)
- break;
- }
- }
-
- if (ret < 0 && !force) {
- for (u = counter; u != c; u = u->parent) {
- spin_lock(&u->lock);
- res_counter_uncharge_locked(u, val);
- spin_unlock(&u->lock);
- }
- }
- local_irq_restore(flags);
-
- return ret;
-}
-
-int res_counter_charge(struct res_counter *counter, unsigned long val,
- struct res_counter **limit_fail_at)
-{
- return __res_counter_charge(counter, val, limit_fail_at, false);
-}
-
-int res_counter_charge_nofail(struct res_counter *counter, unsigned long val,
- struct res_counter **limit_fail_at)
-{
- return __res_counter_charge(counter, val, limit_fail_at, true);
-}
-
-u64 res_counter_uncharge_until(struct res_counter *counter,
- struct res_counter *top,
- unsigned long val)
-{
- unsigned long flags;
- struct res_counter *c;
- u64 ret = 0;
-
- local_irq_save(flags);
- for (c = counter; c != top; c = c->parent) {
- u64 r;
- spin_lock(&c->lock);
- r = res_counter_uncharge_locked(c, val);
- if (c == counter)
- ret = r;
- spin_unlock(&c->lock);
- }
- local_irq_restore(flags);
- return ret;
-}
-
-u64 res_counter_uncharge(struct res_counter *counter, unsigned long val)
-{
- return res_counter_uncharge_until(counter, NULL, val);
-}
-
-static inline unsigned long long *
-res_counter_member(struct res_counter *counter, int member)
-{
- switch (member) {
- case RES_USAGE:
- return &counter->usage;
- case RES_MAX_USAGE:
- return &counter->max_usage;
- case RES_LIMIT:
- return &counter->limit;
- case RES_FAILCNT:
- return &counter->failcnt;
- case RES_SOFT_LIMIT:
- return &counter->soft_limit;
- };
-
- BUG();
- return NULL;
-}
-
-ssize_t res_counter_read(struct res_counter *counter, int member,
- const char __user *userbuf, size_t nbytes, loff_t *pos,
- int (*read_strategy)(unsigned long long val, char *st_buf))
-{
- unsigned long long *val;
- char buf[64], *s;
-
- s = buf;
- val = res_counter_member(counter, member);
- if (read_strategy)
- s += read_strategy(*val, s);
- else
- s += sprintf(s, "%llu\n", *val);
- return simple_read_from_buffer((void __user *)userbuf, nbytes,
- pos, buf, s - buf);
-}
-
-#if BITS_PER_LONG == 32
-u64 res_counter_read_u64(struct res_counter *counter, int member)
-{
- unsigned long flags;
- u64 ret;
-
- spin_lock_irqsave(&counter->lock, flags);
- ret = *res_counter_member(counter, member);
- spin_unlock_irqrestore(&counter->lock, flags);
-
- return ret;
-}
-#else
-u64 res_counter_read_u64(struct res_counter *counter, int member)
-{
- return *res_counter_member(counter, member);
-}
-#endif
-
-int res_counter_memparse_write_strategy(const char *buf,
- unsigned long long *resp)
-{
- char *end;
- unsigned long long res;
-
- /* return RES_COUNTER_MAX(unlimited) if "-1" is specified */
- if (*buf == '-') {
- int rc = kstrtoull(buf + 1, 10, &res);
-
- if (rc)
- return rc;
- if (res != 1)
- return -EINVAL;
- *resp = RES_COUNTER_MAX;
- return 0;
- }
-
- res = memparse(buf, &end);
- if (*end != '\0')
- return -EINVAL;
-
- if (PAGE_ALIGN(res) >= res)
- res = PAGE_ALIGN(res);
- else
- res = RES_COUNTER_MAX;
-
- *resp = res;
-
- return 0;
-}
projects / openwrt / staging / blogic.git / commitdiff