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[PATCH v3 04/13] kmem accounting basic infrastructure [message #47884] Tue, 18 September 2012 14:04 Go to previous message
Glauber Costa is currently offline  Glauber Costa
Messages: 916
Registered: October 2011
Senior Member
This patch adds the basic infrastructure for the accounting of the slab
caches. To control that, the following files are created:

* memory.kmem.usage_in_bytes
* memory.kmem.limit_in_bytes
* memory.kmem.failcnt
* memory.kmem.max_usage_in_bytes

They have the same meaning of their user memory counterparts. They
reflect the state of the "kmem" res_counter.

The code is not enabled until a limit is set. This can be tested by the
flag "kmem_accounted". This means that after the patch is applied, no
behavioral changes exists for whoever is still using memcg to control
their memory usage.

We always account to both user and kernel resource_counters. This
effectively means that an independent kernel limit is in place when the
limit is set to a lower value than the user memory. A equal or higher
value means that the user limit will always hit first, meaning that kmem
is effectively unlimited.

People who want to track kernel memory but not limit it, can set this
limit to a very high number (like RESOURCE_MAX - 1page - that no one
will ever hit, or equal to the user memory)

Signed-off-by: Glauber Costa <glommer@parallels.com>
CC: Michal Hocko <mhocko@suse.cz>
CC: Johannes Weiner <hannes@cmpxchg.org>
Acked-by: Kamezawa Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com>
---
mm/memcontrol.c | 64 ++++++++++++++++++++++++++++++++++++++++++++++++++++++++-
1 file changed, 63 insertions(+), 1 deletion(-)

diff --git a/mm/memcontrol.c b/mm/memcontrol.c
index d6ad138..f3fd354 100644
--- a/mm/memcontrol.c
+++ b/mm/memcontrol.c
@@ -265,6 +265,10 @@ struct mem_cgroup {
};

/*
+ * the counter to account for kernel memory usage.
+ */
+ struct res_counter kmem;
+ /*
* Per cgroup active and inactive list, similar to the
* per zone LRU lists.
*/
@@ -279,6 +283,7 @@ struct mem_cgroup {
* Should the accounting and control be hierarchical, per subtree?
*/
bool use_hierarchy;
+ bool kmem_accounted;

bool oom_lock;
atomic_t under_oom;
@@ -389,6 +394,7 @@ enum res_type {
_MEM,
_MEMSWAP,
_OOM_TYPE,
+ _KMEM,
};

#define MEMFILE_PRIVATE(x, val) ((x) << 16 | (val))
@@ -1439,6 +1445,10 @@ done:
res_counter_read_u64(&memcg->memsw, RES_USAGE) >> 10,
res_counter_read_u64(&memcg->memsw, RES_LIMIT) >> 10,
res_counter_read_u64(&memcg->memsw, RES_FAILCNT));
+ printk(KERN_INFO "kmem: usage %llukB, limit %llukB, failcnt %llu\n",
+ res_counter_read_u64(&memcg->kmem, RES_USAGE) >> 10,
+ res_counter_read_u64(&memcg->kmem, RES_LIMIT) >> 10,
+ res_counter_read_u64(&memcg->kmem, RES_FAILCNT));
}

/*
@@ -3946,6 +3956,9 @@ static ssize_t mem_cgroup_read(struct cgroup *cont, struct cftype *cft,
else
val = res_counter_read_u64(&memcg->memsw, name);
break;
+ case _KMEM:
+ val = res_counter_read_u64(&memcg->kmem, name);
+ break;
default:
BUG();
}
@@ -3984,8 +3997,18 @@ static int mem_cgroup_write(struct cgroup *cont, struct cftype *cft,
break;
if (type == _MEM)
ret = mem_cgroup_resize_limit(memcg, val);
- else
+ else if (type == _MEMSWAP)
ret = mem_cgroup_resize_memsw_limit(memcg, val);
+ else if (type == _KMEM) {
+ ret = res_counter_set_limit(&memcg->kmem, val);
+ if (ret)
+ break;
+
+ /* For simplicity, we won't allow this to be disabled */
+ if (!memcg->kmem_accounted && val != RESOURCE_MAX)
+ memcg->kmem_accounted = true;
+ } else
+ return -EINVAL;
break;
case RES_SOFT_LIMIT:
ret = res_counter_memparse_write_strategy(buffer, &val);
@@ -4051,12 +4074,16 @@ static int mem_cgroup_reset(struct cgroup *cont, unsigned int event)
case RES_MAX_USAGE:
if (type == _MEM)
res_counter_reset_max(&memcg->res);
+ else if (type == _KMEM)
+ res_counter_reset_max(&memcg->kmem);
else
res_counter_reset_max(&memcg->memsw);
break;
case RES_FAILCNT:
if (type == _MEM)
res_counter_reset_failcnt(&memcg->res);
+ else if (type == _KMEM)
+ res_counter_reset_failcnt(&memcg->kmem);
else
res_counter_reset_failcnt(&memcg->memsw);
break;
@@ -4618,6 +4645,33 @@ static int mem_cgroup_oom_control_write(struct cgroup *cgrp,
}

#ifdef CONFIG_MEMCG_KMEM
+static struct cftype kmem_cgroup_files[] = {
+ {
+ .name = "kmem.limit_in_bytes",
+ .private = MEMFILE_PRIVATE(_KMEM, RES_LIMIT),
+ .write_string = mem_cgroup_write,
+ .read = mem_cgroup_read,
+ },
+ {
+ .name = "kmem.usage_in_bytes",
+ .private = MEMFILE_PRIVATE(_KMEM, RES_USAGE),
+ .read = mem_cgroup_read,
+ },
+ {
+ .name = "kmem.failcnt",
+ .private = MEMFILE_PRIVATE(_KMEM, RES_FAILCNT),
+ .trigger = mem_cgroup_reset,
+ .read = mem_cgroup_read,
+ },
+ {
+ .name = "kmem.max_usage_in_bytes",
+ .private = MEMFILE_PRIVATE(_KMEM, RES_MAX_USAGE),
+ .trigger = mem_cgroup_reset,
+ .read = mem_cgroup_read,
+ },
+ {},
+};
+
static int memcg_init_kmem(struct mem_cgroup *memcg, struct cgroup_subsys *ss)
{
return mem_cgroup_sockets_init(memcg, ss);
@@ -4961,6 +5015,12 @@ mem_cgroup_create(struct cgroup *cont)
int cpu;
enable_swap_cgroup();
parent = NULL;
+
+#ifdef CONFIG_MEMCG_KMEM
+ WARN_ON(cgroup_add_cftypes(&mem_cgroup_subsys,
+ kmem_cgroup_files));
+#endif
+
if (mem_cgroup_soft_limit_tree_init())
goto free_out;
root_mem_cgroup = memcg;
@@ -4979,6 +5039,7 @@ mem_cgroup_create(struct cgroup *cont)
if (parent && parent->use_hierarchy) {
res_counter_init(&memcg->res, &parent->res);
res_counter_init(&memcg->memsw, &parent->memsw);
+ res_counter_init(&memcg->kmem, &parent->kmem);
/*
* We increment refcnt of the parent to ensure that we can
* safely access it on res_counter_charge/uncharge.
@@ -4989,6 +5050,7 @@ mem_cgroup_create(struct cgroup *cont)
} else {
res_counter_init(&memcg->res, NULL);
res_counter_init(&memcg->memsw, NULL);
+ res_counter_init(&memcg->kmem, NULL);
}
memcg->last_scanned_node = MAX_NUMNODES;
INIT_LIST_HEAD(&memcg->oom_notify);
--
1.7.11.4

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