The patch titled
memory controller: soft limit interface
has been added to the -mm tree. Its filename is
memory-controller-soft-limit-interface-v9.patch
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------------------------------------------------------
Subject: memory controller: soft limit interface
From: Balbir Singh <balbir@xxxxxxxxxxxxxxxxxx>
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@xxxxxxxxxxxxxxxxxx>
Cc: KAMEZAWA Hiroyuki <kamezawa.hiroyu@xxxxxxxxxxxxxx>
Cc: Li Zefan <lizf@xxxxxxxxxxxxxx>
Cc: KOSAKI Motohiro <kosaki.motohiro@xxxxxxxxxxxxxx>
Signed-off-by: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx>
---
include/linux/res_counter.h | 58 ++++++++++++++++++++++++++++++++++
kernel/res_counter.c | 3 +
mm/memcontrol.c | 20 +++++++++++
3 files changed, 81 insertions(+)
diff -puN include/linux/res_counter.h~memory-controller-soft-limit-interface-v9 include/linux/res_counter.h
--- a/include/linux/res_counter.h~memory-controller-soft-limit-interface-v9
+++ a/include/linux/res_counter.h
@@ -35,6 +35,10 @@ struct res_counter {
*/
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;
@@ -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_che
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_und
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(
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
diff -puN kernel/res_counter.c~memory-controller-soft-limit-interface-v9 kernel/res_counter.c
--- a/kernel/res_counter.c~memory-controller-soft-limit-interface-v9
+++ a/kernel/res_counter.c
@@ -19,6 +19,7 @@ void res_counter_init(struct res_counter
{
spin_lock_init(&counter->lock);
counter->limit = RESOURCE_MAX;
+ counter->soft_limit = RESOURCE_MAX;
counter->parent = parent;
}
@@ -101,6 +102,8 @@ res_counter_member(struct res_counter *c
return &counter->limit;
case RES_FAILCNT:
return &counter->failcnt;
+ case RES_SOFT_LIMIT:
+ return &counter->soft_limit;
};
BUG();
diff -puN mm/memcontrol.c~memory-controller-soft-limit-interface-v9 mm/memcontrol.c
--- a/mm/memcontrol.c~memory-controller-soft-limit-interface-v9
+++ a/mm/memcontrol.c
@@ -2123,6 +2123,20 @@ static int mem_cgroup_write(struct cgrou
else
ret = mem_cgroup_resize_memsw_limit(memcg, val);
break;
+ case RES_SOFT_LIMIT:
+ ret = res_counter_memparse_write_strategy(buffer, &val);
+ if (ret)
+ break;
+ /*
+ * For memsw, soft limits are hard to implement in terms
+ * of semantics, for now, we support soft limits for
+ * control without swap
+ */
+ if (type == _MEM)
+ ret = res_counter_set_soft_limit(&memcg->res, val);
+ else
+ ret = -EINVAL;
+ break;
default:
ret = -EINVAL; /* should be BUG() ? */
break;
@@ -2376,6 +2390,12 @@ static struct cftype mem_cgroup_files[]
.read_u64 = mem_cgroup_read,
},
{
+ .name = "soft_limit_in_bytes",
+ .private = MEMFILE_PRIVATE(_MEM, RES_SOFT_LIMIT),
+ .write_string = mem_cgroup_write,
+ .read_u64 = mem_cgroup_read,
+ },
+ {
.name = "failcnt",
.private = MEMFILE_PRIVATE(_MEM, RES_FAILCNT),
.trigger = mem_cgroup_reset,
_
Patches currently in -mm which might be from balbir@xxxxxxxxxxxxxxxxxx are
linux-next.patch
cgroup-avoid-permanent-sleep-at-rmdir-v7.patch
memcg-remove-the-overhead-associated-with-the-root-cgroup.patch
memcg-remove-the-overhead-associated-with-the-root-cgroup-fix.patch
memcg-remove-the-overhead-associated-with-the-root-cgroup-fix-2.patch
memcg-add-comments-explaining-memory-barriers.patch
memory-controller-soft-limit-documentation-v9.patch
memory-controller-soft-limit-interface-v9.patch
memory-controller-soft-limit-organize-cgroups-v9.patch
memory-controller-soft-limit-refactor-reclaim-flags-v9.patch
memory-controller-soft-limit-reclaim-on-contention-v9.patch
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