[-mm PATCH] Memory controller improve user interface (v2)

[Balbir Singh <balbir@linux.vnet.ibm.com>]

Change the interface to use kilobytes 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.

Signed-off-by: Balbir Singh <balbir@linux.vnet.ibm.com>
---

 Documentation/controllers/memory.txt |   22 +++++++++++++-
 include/linux/res_counter.h          |   10 +++---
 kernel/res_counter.c                 |   30 +++++++++++++------
 mm/memcontrol.c                      |   53 ++++++++++++++++++++++++++++-------
 4 files changed, 90 insertions(+), 25 deletions(-)

diff -puN mm/memcontrol.c~mem-control-make-ui-more-usable mm/memcontrol.c
--- linux-2.6.23-rc3/mm/memcontrol.c~mem-control-make-ui-more-usable	2007-08-29 16:18:39.000000000 +0530
+++ linux-2.6.23-rc3-balbir/mm/memcontrol.c	2007-08-31 00:09:51.000000000 +0530
@@ -312,7 +312,7 @@ int mem_container_charge(struct page *pa
 	 * If we created the page_container, we should free it on exceeding
 	 * the container limit.
 	 */
-	while (res_counter_charge(&mem->res, 1)) {
+	while (res_counter_charge(&mem->res, PAGE_SIZE)) {
 		if (try_to_free_mem_container_pages(mem))
 			continue;
 
@@ -352,7 +352,7 @@ int mem_container_charge(struct page *pa
 		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;
 	}
@@ -417,7 +417,7 @@ void mem_container_uncharge(struct page_
 		css_put(&mem->css);
 		page_assign_page_container(page, NULL);
 		unlock_page_container(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);
@@ -426,12 +426,44 @@ void mem_container_uncharge(struct page_
 	}
 }
 
-static ssize_t mem_container_read(struct container *cont, struct cftype *cft,
-			struct file *file, char __user *userbuf, size_t nbytes,
-			loff_t *ppos)
+/*
+ * Strategy routines for formating read/write data
+ */
+int mem_container_read_strategy(unsigned long long val, char *buf)
+{
+	return sprintf(buf, "%llu Bytes\n", val);
+}
+
+int mem_container_write_strategy(char *buf, unsigned long long *tmp)
+{
+	*tmp = memparse(buf, &buf);
+	if (*buf != '\0')
+		return -EINVAL;
+
+	printk("tmp is %llu\n", *tmp);
+	/*
+	 * Round up the value to the closest page size
+	 */
+	*tmp = ((*tmp + PAGE_SIZE - 1) >> PAGE_SHIFT) << PAGE_SHIFT;
+	return 0;
+}
+
+static ssize_t mem_container_read_usage(struct container *cont,
+			struct cftype *cft, struct file *file,
+			char __user *userbuf, size_t nbytes, loff_t *ppos)
+{
+	return res_counter_read(&mem_container_from_cont(cont)->res,
+				cft->private, userbuf, nbytes, ppos,
+				mem_container_read_strategy);
+}
+
+static ssize_t mem_container_read(struct container *cont,
+			struct cftype *cft, struct file *file,
+			char __user *userbuf, size_t nbytes, loff_t *ppos)
 {
 	return res_counter_read(&mem_container_from_cont(cont)->res,
-				cft->private, userbuf, nbytes, ppos);
+				cft->private, userbuf, nbytes, ppos,
+				NULL);
 }
 
 static ssize_t mem_container_write(struct container *cont, struct cftype *cft,
@@ -439,7 +471,8 @@ static ssize_t mem_container_write(struc
 				size_t nbytes, loff_t *ppos)
 {
 	return res_counter_write(&mem_container_from_cont(cont)->res,
-				cft->private, userbuf, nbytes, ppos);
+				cft->private, userbuf, nbytes, ppos,
+				mem_container_write_strategy);
 }
 
 static ssize_t mem_control_type_write(struct container *cont,
@@ -500,13 +533,13 @@ static struct cftype mem_container_files
 	{
 		.name = "usage",
 		.private = RES_USAGE,
-		.read = mem_container_read,
+		.read = mem_container_read_usage,
 	},
 	{
 		.name = "limit",
 		.private = RES_LIMIT,
 		.write = mem_container_write,
-		.read = mem_container_read,
+		.read = mem_container_read_usage,
 	},
 	{
 		.name = "failcnt",
diff -puN include/linux/memcontrol.h~mem-control-make-ui-more-usable include/linux/memcontrol.h
diff -puN include/linux/res_counter.h~mem-control-make-ui-more-usable include/linux/res_counter.h
--- linux-2.6.23-rc3/include/linux/res_counter.h~mem-control-make-ui-more-usable	2007-08-29 16:18:39.000000000 +0530
+++ linux-2.6.23-rc3-balbir/include/linux/res_counter.h	2007-08-30 23:48:49.000000000 +0530
@@ -23,11 +23,11 @@ struct res_counter {
 	/*
 	 * 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
 	 */
@@ -52,9 +52,11 @@ struct res_counter {
  */
 
 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 -puN kernel/res_counter.c~mem-control-make-ui-more-usable kernel/res_counter.c
--- linux-2.6.23-rc3/kernel/res_counter.c~mem-control-make-ui-more-usable	2007-08-29 16:18:39.000000000 +0530
+++ linux-2.6.23-rc3-balbir/kernel/res_counter.c	2007-08-30 23:49:52.000000000 +0530
@@ -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)
@@ -76,24 +76,29 @@ static inline unsigned long *res_counter
 }
 
 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, "%lu\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 long tmp, *val;
 
 	buf = kmalloc(nbytes + 1, GFP_KERNEL);
 	ret = -ENOMEM;
@@ -106,9 +111,16 @@ ssize_t res_counter_write(struct res_cou
 		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_strtoul(buf, &end, 10);
+		if (*end != '\0')
+			goto out_free;
+	}
 
 	val = res_counter_member(counter, member);
 	*val = tmp;
diff -puN Documentation/controllers/memory.txt~mem-control-make-ui-more-usable Documentation/controllers/memory.txt
--- linux-2.6.23-rc3/Documentation/controllers/memory.txt~mem-control-make-ui-more-usable	2007-08-29 16:18:39.000000000 +0530
+++ linux-2.6.23-rc3-balbir/Documentation/controllers/memory.txt	2007-08-31 00:19:31.000000000 +0530
@@ -165,11 +165,29 @@ c. Enable CONFIG_CONTAINER_MEM_CONT
 
 Since now we're in the 0 container,
 We can alter the memory limit:
-# echo -n 6000 > /containers/0/memory.limit
+# echo -n 4M > /containers/0/memory.limit
+
+NOTE: We can use a suffix (k, K, m, M, g or G) to indicate values in kilo,
+mega or gigabytes.
+
+# cat /containers/0/memory.limit
+4194304 Bytes
+
+NOTE: The interface has now changed to display the usage in bytes
+instead of pages
 
 We can check the usage:
 # cat /containers/0/memory.usage
-25
+1216512 Bytes
+
+Setting a limit to a number that is not a multiple of page size causes
+rounding up of the value. The user must check back to see (by reading
+memory.limit), to check for differences between desired values and committed
+values. Currently, all accounting is done in multiples of PAGE_SIZE
+
+# echo -n 1 > memory.limit
+# cat memory.limit
+4096 Bytes
 
 The memory.failcnt field gives the number of times that the container limit was
 exceeded.
_

-- 
	Warm Regards,
	Balbir Singh
	Linux Technology Center
	IBM, ISTL
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