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memory controller: soft limit interface

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Add an interface to allow get/set of soft limits.  Soft limits for memory
plus swap controller (memsw) is currently not supported.  Resource
counters have been enhanced to support soft limits and new type
RES_SOFT_LIMIT has been added.  Unlike hard limits, soft limits can be
directly set and do not need any reclaim or checks before setting them to
a newer value.

Kamezawa-San raised a question as to whether soft limit should belong to
res_counter.  Since all resources understand the basic concepts of hard
and soft limits, it is justified to add soft limits here.  Soft limits are
a generic resource usage feature, even file system quotas support soft
limits.

Signed-off-by: Balbir Singh <balbir@linux.vnet.ibm.com>
Cc: KAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com>
Cc: Li Zefan <lizf@cn.fujitsu.com>
Cc: KOSAKI Motohiro <kosaki.motohiro@jp.fujitsu.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
This commit is contained in:
Balbir Singh
2009-09-23 15:56:36 -07:00
committed by Linus Torvalds
parent a6df63615b
commit 296c81d89f
3 changed files with 81 additions and 0 deletions
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58
include/linux/res_counter.h
View File

@@ -34,6 +34,10 @@ struct res_counter {
* 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
*/
@@ -87,6 +91,7 @@ enum {
RES_MAX_USAGE,
RES_LIMIT,
RES_FAILCNT,
RES_SOFT_LIMIT,
};
/*
@@ -132,6 +137,36 @@ static inline bool res_counter_limit_check_locked(struct res_counter *cnt)
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()
@@ -147,6 +182,17 @@ static inline bool res_counter_check_under_limit(struct res_counter *cnt)
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;
@@ -180,4 +226,16 @@ static inline int res_counter_set_limit(struct res_counter *cnt,
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