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>
diff --git a/Documentation/controllers/memory.txt b/Documentation/controllers/memory.txt
index 7e27baa..61df8f8 100644
--- a/Documentation/controllers/memory.txt
+++ b/Documentation/controllers/memory.txt
@@ -165,11 +165,30 @@
Since now we're in the 0 cgroup,
We can alter the memory limit:
-# echo -n 6000 > /cgroups/0/memory.limit
+# echo -n 4M > /cgroups/0/memory.limit_in_bytes
+
+NOTE: We can use a suffix (k, K, m, M, g or G) to indicate values in kilo,
+mega or gigabytes.
+
+# cat /cgroups/0/memory.limit_in_bytes
+4194304 Bytes
+
+NOTE: The interface has now changed to display the usage in bytes
+instead of pages
We can check the usage:
-# cat /cgroups/0/memory.usage
-25
+# cat /cgroups/0/memory.usage_in_bytes
+1216512 Bytes
+
+A successful write to this file does not guarantee a successful set of
+this limit to the value written into the file. This can be due to a
+number of factors, such as rounding up to page boundaries or the total
+availability of memory on the system. The user is required to re-read
+this file after a write to guarantee the value committed by the kernel.
+
+# echo -n 1 > memory.limit_in_bytes
+# cat memory.limit_in_bytes
+4096 Bytes
The memory.failcnt field gives the number of times that the cgroup limit was
exceeded.
@@ -206,8 +225,8 @@
tasks have migrated away from it. If some pages are still left, after following
the steps listed in sections 4.1 and 4.2, check the Swap Cache usage in
/proc/meminfo to see if the Swap Cache usage is showing up in the
-cgroups memory.usage counter. A simple test of swapoff -a and swapon -a
-should free any pending Swap Cache usage.
+cgroups memory.usage_in_bytes counter. A simple test of swapoff -a and
+swapon -a should free any pending Swap Cache usage.
4.4 Choosing what to account -- Page Cache (unmapped) vs RSS (mapped)?
diff --git a/include/linux/res_counter.h b/include/linux/res_counter.h
index 5e60a4f..61363ce 100644
--- a/include/linux/res_counter.h
+++ b/include/linux/res_counter.h
@@ -23,15 +23,15 @@
/*
* the current resource consumption level
*/
- unsigned long usage;
+ unsigned long long usage;
/*
* the limit that usage cannot exceed
*/
- unsigned long limit;
+ unsigned long long limit;
/*
* the number of unsuccessful attempts to consume the resource
*/
- unsigned long failcnt;
+ unsigned long long failcnt;
/*
* the lock to protect all of the above.
* the routines below consider this to be IRQ-safe
@@ -52,9 +52,11 @@
*/
ssize_t res_counter_read(struct res_counter *counter, int member,
- const char __user *buf, size_t nbytes, loff_t *pos);
+ const char __user *buf, size_t nbytes, loff_t *pos,
+ int (*read_strategy)(unsigned long long val, char *s));
ssize_t res_counter_write(struct res_counter *counter, int member,
- const char __user *buf, size_t nbytes, loff_t *pos);
+ const char __user *buf, size_t nbytes, loff_t *pos,
+ int (*write_strategy)(char *buf, unsigned long long *val));
/*
* the field descriptors. one for each member of res_counter
diff --git a/kernel/res_counter.c b/kernel/res_counter.c
index 722c484..16cbec2 100644
--- a/kernel/res_counter.c
+++ b/kernel/res_counter.c
@@ -16,7 +16,7 @@
void res_counter_init(struct res_counter *counter)
{
spin_lock_init(&counter->lock);
- counter->limit = (unsigned long)LONG_MAX;
+ counter->limit = (unsigned long long)LLONG_MAX;
}
int res_counter_charge_locked(struct res_counter *counter, unsigned long val)
@@ -59,8 +59,8 @@
}
-static inline unsigned long *res_counter_member(struct res_counter *counter,
- int member)
+static inline unsigned long long *
+res_counter_member(struct res_counter *counter, int member)
{
switch (member) {
case RES_USAGE:
@@ -76,24 +76,30 @@
}
ssize_t res_counter_read(struct res_counter *counter, int member,
- const char __user *userbuf, size_t nbytes, loff_t *pos)
+ const char __user *userbuf, size_t nbytes, loff_t *pos,
+ int (*read_strategy)(unsigned long long val, char *st_buf))
{
- unsigned long *val;
+ unsigned long long *val;
char buf[64], *s;
s = buf;
val = res_counter_member(counter, member);
- s += sprintf(s, "%lu\n", *val);
+ if (read_strategy)
+ s += read_strategy(*val, s);
+ else
+ s += sprintf(s, "%llu\n", *val);
return simple_read_from_buffer((void __user *)userbuf, nbytes,
pos, buf, s - buf);
}
ssize_t res_counter_write(struct res_counter *counter, int member,
- const char __user *userbuf, size_t nbytes, loff_t *pos)
+ const char __user *userbuf, size_t nbytes, loff_t *pos,
+ int (*write_strategy)(char *st_buf, unsigned long long *val))
{
int ret;
char *buf, *end;
- unsigned long tmp, *val;
+ unsigned long flags;
+ unsigned long long tmp, *val;
buf = kmalloc(nbytes + 1, GFP_KERNEL);
ret = -ENOMEM;
@@ -106,12 +112,20 @@
goto out_free;
ret = -EINVAL;
- tmp = simple_strtoul(buf, &end, 10);
- if (*end != '\0')
- goto out_free;
+ if (write_strategy) {
+ if (write_strategy(buf, &tmp)) {
+ goto out_free;
+ }
+ } else {
+ tmp = simple_strtoull(buf, &end, 10);
+ if (*end != '\0')
+ goto out_free;
+ }
+ spin_lock_irqsave(&counter->lock, flags);
val = res_counter_member(counter, member);
*val = tmp;
+ spin_unlock_irqrestore(&counter->lock, flags);
ret = nbytes;
out_free:
kfree(buf);
diff --git a/mm/memcontrol.c b/mm/memcontrol.c
index 9e9ff91..d736922 100644
--- a/mm/memcontrol.c
+++ b/mm/memcontrol.c
@@ -302,7 +302,7 @@
* 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 @@
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 @@
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 @@
}
}
-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 @@
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,
