From: KAMEZAWA Hiroyuki <kamezawa.hiroyu@xxxxxxxxxxxxxx>
Now, memory cgroup has an ID(1-65535) per a group and use it for
walking hierarchy, recording it for swapped-out resources etc...
This patch tries to make use of it more. Allocating memory cgroup
into an (virtual) array. This allows to access a memory cgroup by
mem = mem_cgroup_base + id.
By this, we don't have to use css_lookup() and will have a chance to
replace a pointer to mem_cgroup(8bytes on 64bit) to an ID (2bytes).
Thought:
- Although I added CONFIG in this patch, I wonder I should remove it..
Signed-off-by: KAMEZAWA Hiroyuki <kamezawa.hiroyu@xxxxxxxxxxxxxx>
---
init/Kconfig | 14 +++++++-
mm/memcontrol.c | 93 ++++++++++++++++++++++++++++++--------------------------
2 files changed, 63 insertions(+), 44 deletions(-)
Index: mmotm-0719/init/Kconfig
===================================================================
--- mmotm-0719.orig/init/Kconfig
+++ mmotm-0719/init/Kconfig
@@ -555,7 +555,7 @@ config RESOURCE_COUNTERS
config CGROUP_MEM_RES_CTLR
bool "Memory Resource Controller for Control Groups"
- depends on CGROUPS && RESOURCE_COUNTERS
+ depends on CGROUPS && RESOURCE_COUNTERS && MMU
select MM_OWNER
help
Provides a memory resource controller that manages both anonymous
@@ -594,6 +594,18 @@ config CGROUP_MEM_RES_CTLR_SWAP
Now, memory usage of swap_cgroup is 2 bytes per entry. If swap page
size is 4096bytes, 512k per 1Gbytes of swap.
+config MEM_CGROUP_MAX_GROUPS
+ int "Maximum number of memory cgroups on a system"
+ range 1 65535 if 64BIT
+ default 8192 if 64BIT
+ range 1 4096 if 32BIT
+ default 2048 if 32BIT
+ help
+ Memory cgroup has limitation of the number of groups created.
+ Please select your favorite value. The more you allow, the more
+ memory will be consumed. This consumes vmalloc() area, so,
+ this should be small on 32bit arch.
+
menuconfig CGROUP_SCHED
bool "Group CPU scheduler"
depends on EXPERIMENTAL && CGROUPS
Index: mmotm-0719/mm/memcontrol.c
===================================================================
--- mmotm-0719.orig/mm/memcontrol.c
+++ mmotm-0719/mm/memcontrol.c
@@ -48,6 +48,7 @@
#include <linux/page_cgroup.h>
#include <linux/cpu.h>
#include <linux/oom.h>
+#include <linux/virt-array.h>
#include "internal.h"
#include <asm/uaccess.h>
@@ -242,7 +243,8 @@ struct mem_cgroup {
/* For oom notifier event fd */
struct list_head oom_notify;
-
+ /* Used when varray is used */
+ int custom_id;
/*
* Should we move charges of a task when a task is moved into this
* mem_cgroup ? And what type of charges should we move ?
@@ -254,6 +256,8 @@ struct mem_cgroup {
struct mem_cgroup_stat_cpu *stat;
};
+static struct mem_cgroup *mem_cgroup_base __read_mostly;
+
/* Stuffs for move charges at task migration. */
/*
* Types of charges to be moved. "move_charge_at_immitgrate" is treated as a
@@ -341,6 +345,19 @@ static void mem_cgroup_put(struct mem_cg
static struct mem_cgroup *parent_mem_cgroup(struct mem_cgroup *mem);
static void drain_all_stock_async(void);
+/*
+ * A helper function to get mem_cgroup from ID. must be called under
+ * rcu_read_lock(). The caller must check css_is_removed() or some if
+ * it's concern. (dropping refcnt from swap can be called against removed
+ * memcg.)
+ */
+static struct mem_cgroup *id_to_mem(unsigned short id)
+{
+ if (id)
+ return mem_cgroup_base + id;
+ return NULL;
+}
+
static struct mem_cgroup_per_zone *
mem_cgroup_zoneinfo(struct mem_cgroup *mem, int nid, int zid)
{
@@ -1818,24 +1835,6 @@ static void mem_cgroup_cancel_charge(str
__mem_cgroup_cancel_charge(mem, 1);
}
-/*
- * A helper function to get mem_cgroup from ID. must be called under
- * rcu_read_lock(). The caller must check css_is_removed() or some if
- * it's concern. (dropping refcnt from swap can be called against removed
- * memcg.)
- */
-static struct mem_cgroup *mem_cgroup_lookup(unsigned short id)
-{
- struct cgroup_subsys_state *css;
-
- /* ID 0 is unused ID */
- if (!id)
- return NULL;
- css = css_lookup(&mem_cgroup_subsys, id);
- if (!css)
- return NULL;
- return container_of(css, struct mem_cgroup, css);
-}
struct mem_cgroup *try_get_mem_cgroup_from_page(struct page *page)
{
@@ -1856,7 +1855,7 @@ struct mem_cgroup *try_get_mem_cgroup_fr
ent.val = page_private(page);
id = lookup_swap_cgroup(ent);
rcu_read_lock();
- mem = mem_cgroup_lookup(id);
+ mem = id_to_mem(id);
if (mem && !css_tryget(&mem->css))
mem = NULL;
rcu_read_unlock();
@@ -2208,7 +2207,7 @@ __mem_cgroup_commit_charge_swapin(struct
id = swap_cgroup_record(ent, 0);
rcu_read_lock();
- memcg = mem_cgroup_lookup(id);
+ memcg = id_to_mem(id);
if (memcg) {
/*
* This recorded memcg can be obsolete one. So, avoid
@@ -2472,7 +2471,7 @@ void mem_cgroup_uncharge_swap(swp_entry_
id = swap_cgroup_record(ent, 0);
rcu_read_lock();
- memcg = mem_cgroup_lookup(id);
+ memcg = id_to_mem(id);
if (memcg) {
/*
* We uncharge this because swap is freed.
@@ -3983,32 +3982,42 @@ static void free_mem_cgroup_per_zone_inf
kfree(mem->info.nodeinfo[node]);
}
-static struct mem_cgroup *mem_cgroup_alloc(void)
+struct virt_array memcg_varray;
+
+static int mem_cgroup_custom_id(struct cgroup_subsys *ss, struct cgroup *cont)
{
- struct mem_cgroup *mem;
- int size = sizeof(struct mem_cgroup);
+ struct mem_cgroup *mem = mem_cgroup_from_cont(cont);
+ return mem->custom_id;
+}
- /* Can be very big if MAX_NUMNODES is very big */
- if (size < PAGE_SIZE)
- mem = kmalloc(size, GFP_KERNEL);
- else
- mem = vmalloc(size);
+static struct mem_cgroup *mem_cgroup_alloc(struct cgroup *cgroup)
+{
+ struct mem_cgroup *mem;
+ int idx;
- if (!mem)
+ if (cgroup->parent == NULL) {
+ mem_cgroup_base = create_varray(&memcg_varray, sizeof(*mem),
+ CONFIG_MEM_CGROUP_MAX_GROUPS);
+ BUG_ON(IS_ERR_OR_NULL(mem_cgroup_base));
+ }
+ /* 0 is unused ID.(see css_id's spec). */
+ idx = varray_find_free_index(&memcg_varray, 1);
+ if (idx == memcg_varray.nelem)
return NULL;
-
- memset(mem, 0, size);
+ mem = alloc_varray_item(&memcg_varray, idx);
+ if (IS_ERR_OR_NULL(mem))
+ return NULL;
+ memset(mem, 0, sizeof(*mem));
mem->stat = alloc_percpu(struct mem_cgroup_stat_cpu);
if (!mem->stat) {
- if (size < PAGE_SIZE)
- kfree(mem);
- else
- vfree(mem);
+ free_varray_item(&memcg_varray, idx);
mem = NULL;
- }
+ } else
+ mem->custom_id = idx;
return mem;
}
+
/*
* At destroying mem_cgroup, references from swap_cgroup can remain.
* (scanning all at force_empty is too costly...)
@@ -4031,10 +4040,7 @@ static void __mem_cgroup_free(struct mem
free_mem_cgroup_per_zone_info(mem, node);
free_percpu(mem->stat);
- if (sizeof(struct mem_cgroup) < PAGE_SIZE)
- kfree(mem);
- else
- vfree(mem);
+ free_varray_item(&memcg_varray, mem->custom_id);
}
static void mem_cgroup_get(struct mem_cgroup *mem)
@@ -4111,7 +4117,7 @@ mem_cgroup_create(struct cgroup_subsys *
long error = -ENOMEM;
int node;
- mem = mem_cgroup_alloc();
+ mem = mem_cgroup_alloc(cont);
if (!mem)
return ERR_PTR(error);
@@ -4692,6 +4698,7 @@ struct cgroup_subsys mem_cgroup_subsys =
.can_attach = mem_cgroup_can_attach,
.cancel_attach = mem_cgroup_cancel_attach,
.attach = mem_cgroup_move_task,
+ .custom_id = mem_cgroup_custom_id,
.early_init = 0,
.use_id = 1,
};
--
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