Memory controller improve user interface

Change the interface to use bytes instead of pages.  Page sizes can vary
across platforms and configurations.  A new strategy routine has been added
to the resource counters infrastructure to format the data as desired.

Suggested by David Rientjes, Andrew Morton and Herbert Poetzl

Tested on a UML setup with the config for memory control enabled.

[kamezawa.hiroyu@jp.fujitsu.com: possible race fix in res_counter]
Signed-off-by: Balbir Singh <balbir@linux.vnet.ibm.com>
Signed-off-by: Pavel Emelianov <xemul@openvz.org>
Cc: Paul Menage <menage@google.com>
Cc: Peter Zijlstra <a.p.zijlstra@chello.nl>
Cc: "Eric W. Biederman" <ebiederm@xmission.com>
Cc: Nick Piggin <nickpiggin@yahoo.com.au>
Cc: Kirill Korotaev <dev@sw.ru>
Cc: Herbert Poetzl <herbert@13thfloor.at>
Cc: David Rientjes <rientjes@google.com>
Cc: Vaidyanathan Srinivasan <svaidy@linux.vnet.ibm.com>
Signed-off-by: KAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

1 files changed, 25 insertions, 10 deletions

diff --git a/mm/memcontrol.c b/mm/memcontrol.c
index 9e9ff914c0f1..d73692279ab1 100644
--- a/mm/memcontrol.c
+++ b/mm/memcontrol.c
@@ -302,7 +302,7 @@ retry:
 	 * If we created the page_cgroup, we should free it on exceeding
 	 * the cgroup limit.
 	 */
-	while (res_counter_charge(&mem->res, 1)) {
+	while (res_counter_charge(&mem->res, PAGE_SIZE)) {
 		if (try_to_free_mem_cgroup_pages(mem))
 			continue;
 
@@ -341,7 +341,7 @@ retry:
 		kfree(pc);
 		pc = race_pc;
 		atomic_inc(&pc->ref_cnt);
-		res_counter_uncharge(&mem->res, 1);
+		res_counter_uncharge(&mem->res, PAGE_SIZE);
 		css_put(&mem->css);
 		goto done;
 	}
@@ -384,7 +384,7 @@ void mem_cgroup_uncharge(struct page_cgroup *pc)
 		css_put(&mem->css);
 		page_assign_page_cgroup(page, NULL);
 		unlock_page_cgroup(page);
-		res_counter_uncharge(&mem->res, 1);
+		res_counter_uncharge(&mem->res, PAGE_SIZE);
 
  		spin_lock_irqsave(&mem->lru_lock, flags);
  		list_del_init(&pc->lru);
@@ -393,12 +393,26 @@ void mem_cgroup_uncharge(struct page_cgroup *pc)
 	}
 }
 
-static ssize_t mem_cgroup_read(struct cgroup *cont, struct cftype *cft,
-			struct file *file, char __user *userbuf, size_t nbytes,
-			loff_t *ppos)
+int mem_cgroup_write_strategy(char *buf, unsigned long long *tmp)
+{
+	*tmp = memparse(buf, &buf);
+	if (*buf != '\0')
+		return -EINVAL;
+
+	/*
+	 * Round up the value to the closest page size
+	 */
+	*tmp = ((*tmp + PAGE_SIZE - 1) >> PAGE_SHIFT) << PAGE_SHIFT;
+	return 0;
+}
+
+static ssize_t mem_cgroup_read(struct cgroup *cont,
+			struct cftype *cft, struct file *file,
+			char __user *userbuf, size_t nbytes, loff_t *ppos)
 {
 	return res_counter_read(&mem_cgroup_from_cont(cont)->res,
-				cft->private, userbuf, nbytes, ppos);
+				cft->private, userbuf, nbytes, ppos,
+				NULL);
 }
 
 static ssize_t mem_cgroup_write(struct cgroup *cont, struct cftype *cft,
@@ -406,17 +420,18 @@ static ssize_t mem_cgroup_write(struct cgroup *cont, struct cftype *cft,
 				size_t nbytes, loff_t *ppos)
 {
 	return res_counter_write(&mem_cgroup_from_cont(cont)->res,
-				cft->private, userbuf, nbytes, ppos);
+				cft->private, userbuf, nbytes, ppos,
+				mem_cgroup_write_strategy);
 }
 
 static struct cftype mem_cgroup_files[] = {
 	{
-		.name = "usage",
+		.name = "usage_in_bytes",
 		.private = RES_USAGE,
 		.read = mem_cgroup_read,
 	},
 	{
-		.name = "limit",
+		.name = "limit_in_bytes",
 		.private = RES_LIMIT,
 		.write = mem_cgroup_write,
 		.read = mem_cgroup_read,