kernel-ark/include/linux/res_counter.h
KAMEZAWA Hiroyuki 4e649152cb memcg: some modification to softlimit under hierarchical memory reclaim.
This patch clean up/fixes for memcg's uncharge soft limit path.

Problems:
  Now, res_counter_charge()/uncharge() handles softlimit information at
  charge/uncharge and softlimit-check is done when event counter per memcg
  goes over limit. Now, event counter per memcg is updated only when
  memory usage is over soft limit. Here, considering hierarchical memcg
  management, ancesotors should be taken care of.

  Now, ancerstors(hierarchy) are handled in charge() but not in uncharge().
  This is not good.

  Prolems:
  1. memcg's event counter incremented only when softlimit hits. That's bad.
     It makes event counter hard to be reused for other purpose.

  2. At uncharge, only the lowest level rescounter is handled. This is bug.
     Because ancesotor's event counter is not incremented, children should
     take care of them.

  3. res_counter_uncharge()'s 3rd argument is NULL in most case.
     ops under res_counter->lock should be small. No "if" sentense is better.

Fixes:
  * Removed soft_limit_xx poitner and checks in charge and uncharge.
    Do-check-only-when-necessary scheme works enough well without them.

  * make event-counter of memcg incremented at every charge/uncharge.
    (per-cpu area will be accessed soon anyway)

  * All ancestors are checked at soft-limit-check. This is necessary because
    ancesotor's event counter may never be modified. Then, they should be
    checked at the same time.

Reviewed-by: Daisuke Nishimura <nishimura@mxp.nes.nec.co.jp>
Signed-off-by: KAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com>
Cc: Paul Menage <menage@google.com>
Cc: Li Zefan <lizf@cn.fujitsu.com>
Cc: Balbir Singh <balbir@in.ibm.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2009-10-01 16:11:13 -07:00

242 lines
5.8 KiB
C

#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/cgroup.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 RESOURCE_MAX (unsigned long long)LLONG_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));
typedef int (*write_strategy_fn)(const char *buf, unsigned long long *val);
int res_counter_memparse_write_strategy(const char *buf,
unsigned long long *res);
int res_counter_write(struct res_counter *counter, int member,
const char *buffer, write_strategy_fn write_strategy);
/*
* 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 _locked call expects the counter->lock to be taken
*/
int __must_check res_counter_charge_locked(struct res_counter *counter,
unsigned long val);
int __must_check res_counter_charge(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
* _locked call expects the counter->lock to be taken
*/
void res_counter_uncharge_locked(struct res_counter *counter, unsigned long val);
void res_counter_uncharge(struct res_counter *counter, unsigned long val);
static inline bool res_counter_limit_check_locked(struct res_counter *cnt)
{
if (cnt->usage < cnt->limit)
return true;
return false;
}
static inline bool res_counter_soft_limit_check_locked(struct res_counter *cnt)
{
if (cnt->usage < cnt->soft_limit)
return true;
return false;
}
/**
* 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;
}
/*
* Helper function to detect if the cgroup is within it's limit or
* not. It's currently called from cgroup_rss_prepare()
*/
static inline bool res_counter_check_under_limit(struct res_counter *cnt)
{
bool ret;
unsigned long flags;
spin_lock_irqsave(&cnt->lock, flags);
ret = res_counter_limit_check_locked(cnt);
spin_unlock_irqrestore(&cnt->lock, flags);
return ret;
}
static inline bool res_counter_check_under_soft_limit(struct res_counter *cnt)
{
bool ret;
unsigned long flags;
spin_lock_irqsave(&cnt->lock, flags);
ret = res_counter_soft_limit_check_locked(cnt);
spin_unlock_irqrestore(&cnt->lock, flags);
return ret;
}
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