memcg: swappiness
Currently, /proc/sys/vm/swappiness can change swappiness ratio for global
reclaim. However, memcg reclaim doesn't have tuning parameter for itself.
In general, the optimal swappiness depend on workload. (e.g. hpc
workload need to low swappiness than the others.)
Then, per cgroup swappiness improve administrator tunability.
Signed-off-by: KAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com>
Signed-off-by: KOSAKI Motohiro <kosaki.motohiro@jp.fujitsu.com>
Cc: Balbir Singh <balbir@in.ibm.com>
Cc: Daisuke Nishimura <nishimura@mxp.nes.nec.co.jp>
Cc: Hugh Dickins <hugh@veritas.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/Documentation/controllers/memory.txt b/Documentation/controllers/memory.txt
index d71745c..e150196 100644
--- a/Documentation/controllers/memory.txt
+++ b/Documentation/controllers/memory.txt
@@ -314,6 +314,15 @@
showing for better debug please see the code for meanings.
+5.3 swappiness
+ Similar to /proc/sys/vm/swappiness, but affecting a hierarchy of groups only.
+
+ Following cgroup's swapiness can't be changed.
+ - root cgroup (uses /proc/sys/vm/swappiness).
+ - a cgroup which uses hierarchy and it has child cgroup.
+ - a cgroup which uses hierarchy and not the root of hierarchy.
+
+
6. Hierarchy support
The memory controller supports a deep hierarchy and hierarchical accounting.
diff --git a/include/linux/swap.h b/include/linux/swap.h
index be938ce..4ccca25 100644
--- a/include/linux/swap.h
+++ b/include/linux/swap.h
@@ -214,7 +214,8 @@
extern unsigned long try_to_free_pages(struct zonelist *zonelist, int order,
gfp_t gfp_mask);
extern unsigned long try_to_free_mem_cgroup_pages(struct mem_cgroup *mem,
- gfp_t gfp_mask, bool noswap);
+ gfp_t gfp_mask, bool noswap,
+ unsigned int swappiness);
extern int __isolate_lru_page(struct page *page, int mode, int file);
extern unsigned long shrink_all_memory(unsigned long nr_pages);
extern int vm_swappiness;
diff --git a/mm/memcontrol.c b/mm/memcontrol.c
index 027c0dd..ab2ecbb 100644
--- a/mm/memcontrol.c
+++ b/mm/memcontrol.c
@@ -164,6 +164,9 @@
int obsolete;
atomic_t refcnt;
+ unsigned int swappiness;
+
+
unsigned int inactive_ratio;
/*
@@ -636,6 +639,22 @@
return false;
}
+static unsigned int get_swappiness(struct mem_cgroup *memcg)
+{
+ struct cgroup *cgrp = memcg->css.cgroup;
+ unsigned int swappiness;
+
+ /* root ? */
+ if (cgrp->parent == NULL)
+ return vm_swappiness;
+
+ spin_lock(&memcg->reclaim_param_lock);
+ swappiness = memcg->swappiness;
+ spin_unlock(&memcg->reclaim_param_lock);
+
+ return swappiness;
+}
+
/*
* Dance down the hierarchy if needed to reclaim memory. We remember the
* last child we reclaimed from, so that we don't end up penalizing
@@ -656,7 +675,8 @@
* but there might be left over accounting, even after children
* have left.
*/
- ret = try_to_free_mem_cgroup_pages(root_mem, gfp_mask, noswap);
+ ret = try_to_free_mem_cgroup_pages(root_mem, gfp_mask, noswap,
+ get_swappiness(root_mem));
if (mem_cgroup_check_under_limit(root_mem))
return 0;
if (!root_mem->use_hierarchy)
@@ -672,7 +692,8 @@
cgroup_unlock();
continue;
}
- ret = try_to_free_mem_cgroup_pages(next_mem, gfp_mask, noswap);
+ ret = try_to_free_mem_cgroup_pages(next_mem, gfp_mask, noswap,
+ get_swappiness(next_mem));
if (mem_cgroup_check_under_limit(root_mem))
return 0;
cgroup_lock();
@@ -1400,7 +1421,8 @@
rcu_read_unlock();
do {
- progress = try_to_free_mem_cgroup_pages(mem, gfp_mask, true);
+ progress = try_to_free_mem_cgroup_pages(mem, gfp_mask, true,
+ get_swappiness(mem));
progress += mem_cgroup_check_under_limit(mem);
} while (!progress && --retry);
@@ -1468,7 +1490,9 @@
break;
progress = try_to_free_mem_cgroup_pages(memcg,
- GFP_KERNEL, false);
+ GFP_KERNEL,
+ false,
+ get_swappiness(memcg));
if (!progress) retry_count--;
}
@@ -1512,7 +1536,8 @@
break;
oldusage = res_counter_read_u64(&memcg->memsw, RES_USAGE);
- try_to_free_mem_cgroup_pages(memcg, GFP_KERNEL, true);
+ try_to_free_mem_cgroup_pages(memcg, GFP_KERNEL, true,
+ get_swappiness(memcg));
curusage = res_counter_read_u64(&memcg->memsw, RES_USAGE);
if (curusage >= oldusage)
retry_count--;
@@ -1643,8 +1668,8 @@
ret = -EINTR;
goto out;
}
- progress = try_to_free_mem_cgroup_pages(mem,
- GFP_KERNEL, false);
+ progress = try_to_free_mem_cgroup_pages(mem, GFP_KERNEL,
+ false, get_swappiness(mem));
if (!progress) {
nr_retries--;
/* maybe some writeback is necessary */
@@ -1864,6 +1889,37 @@
return 0;
}
+static u64 mem_cgroup_swappiness_read(struct cgroup *cgrp, struct cftype *cft)
+{
+ struct mem_cgroup *memcg = mem_cgroup_from_cont(cgrp);
+
+ return get_swappiness(memcg);
+}
+
+static int mem_cgroup_swappiness_write(struct cgroup *cgrp, struct cftype *cft,
+ u64 val)
+{
+ struct mem_cgroup *memcg = mem_cgroup_from_cont(cgrp);
+ struct mem_cgroup *parent;
+ if (val > 100)
+ return -EINVAL;
+
+ if (cgrp->parent == NULL)
+ return -EINVAL;
+
+ parent = mem_cgroup_from_cont(cgrp->parent);
+ /* If under hierarchy, only empty-root can set this value */
+ if ((parent->use_hierarchy) ||
+ (memcg->use_hierarchy && !list_empty(&cgrp->children)))
+ return -EINVAL;
+
+ spin_lock(&memcg->reclaim_param_lock);
+ memcg->swappiness = val;
+ spin_unlock(&memcg->reclaim_param_lock);
+
+ return 0;
+}
+
static struct cftype mem_cgroup_files[] = {
{
@@ -1902,6 +1958,11 @@
.write_u64 = mem_cgroup_hierarchy_write,
.read_u64 = mem_cgroup_hierarchy_read,
},
+ {
+ .name = "swappiness",
+ .read_u64 = mem_cgroup_swappiness_read,
+ .write_u64 = mem_cgroup_swappiness_write,
+ },
};
#ifdef CONFIG_CGROUP_MEM_RES_CTLR_SWAP
@@ -2093,6 +2154,9 @@
mem->last_scanned_child = NULL;
spin_lock_init(&mem->reclaim_param_lock);
+ if (parent)
+ mem->swappiness = get_swappiness(parent);
+
return &mem->css;
free_out:
for_each_node_state(node, N_POSSIBLE)
diff --git a/mm/vmscan.c b/mm/vmscan.c
index f03c239..ece2f40 100644
--- a/mm/vmscan.c
+++ b/mm/vmscan.c
@@ -1707,14 +1707,15 @@
#ifdef CONFIG_CGROUP_MEM_RES_CTLR
unsigned long try_to_free_mem_cgroup_pages(struct mem_cgroup *mem_cont,
- gfp_t gfp_mask,
- bool noswap)
+ gfp_t gfp_mask,
+ bool noswap,
+ unsigned int swappiness)
{
struct scan_control sc = {
.may_writepage = !laptop_mode,
.may_swap = 1,
.swap_cluster_max = SWAP_CLUSTER_MAX,
- .swappiness = vm_swappiness,
+ .swappiness = swappiness,
.order = 0,
.mem_cgroup = mem_cont,
.isolate_pages = mem_cgroup_isolate_pages,