memory controller: soft limit interface
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>
diff --git a/kernel/res_counter.c b/kernel/res_counter.c
index e1338f0..bcdabf3 100644
--- a/kernel/res_counter.c
+++ b/kernel/res_counter.c
@@ -19,6 +19,7 @@
{
spin_lock_init(&counter->lock);
counter->limit = RESOURCE_MAX;
+ counter->soft_limit = RESOURCE_MAX;
counter->parent = parent;
}
@@ -101,6 +102,8 @@
return &counter->limit;
case RES_FAILCNT:
return &counter->failcnt;
+ case RES_SOFT_LIMIT:
+ return &counter->soft_limit;
};
BUG();