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Subject[PATCH 6/6] cpuset dirty limits
Per cpuset dirty ratios

This implements dirty ratios per cpuset. Two new files are added
to the cpuset directories:

background_dirty_ratio Percentage at which background writeback starts

throttle_dirty_ratio Percentage at which the application is throttled
and we start synchrononous writeout.

Both variables are set to -1 by default which means that the global
limits (/proc/sys/vm/vm_dirty_ratio and /proc/sys/vm/dirty_background_ratio)
are used for a cpuset.

Signed-off-by: Christoph Lameter <clameter@sgi.com>
Acked-by: Ethan Solomita <solo@google.com>

---
Patch against 2.6.23-rc4-mm1

diff -uprN -X 0/Documentation/dontdiff 5/include/linux/cpuset.h 7/include/linux/cpuset.h
--- 5/include/linux/cpuset.h 2007-09-11 14:50:48.000000000 -0700
+++ 7/include/linux/cpuset.h 2007-09-11 14:51:12.000000000 -0700
@@ -77,6 +77,7 @@ extern void cpuset_track_online_nodes(vo

extern int current_cpuset_is_being_rebound(void);

+extern void cpuset_get_current_ratios(int *background, int *ratio);
/*
* We need macros since struct address_space is not defined yet
*/
diff -uprN -X 0/Documentation/dontdiff 5/kernel/cpuset.c 7/kernel/cpuset.c
--- 5/kernel/cpuset.c 2007-09-11 14:50:49.000000000 -0700
+++ 7/kernel/cpuset.c 2007-09-11 14:56:18.000000000 -0700
@@ -51,6 +51,7 @@
#include <linux/time.h>
#include <linux/backing-dev.h>
#include <linux/sort.h>
+#include <linux/writeback.h>

#include <asm/uaccess.h>
#include <asm/atomic.h>
@@ -92,6 +93,9 @@ struct cpuset {
int mems_generation;

struct fmeter fmeter; /* memory_pressure filter */
+
+ int background_dirty_ratio;
+ int throttle_dirty_ratio;
};

/* Retrieve the cpuset for a container */
@@ -169,6 +173,8 @@ static struct cpuset top_cpuset = {
.flags = ((1 << CS_CPU_EXCLUSIVE) | (1 << CS_MEM_EXCLUSIVE)),
.cpus_allowed = CPU_MASK_ALL,
.mems_allowed = NODE_MASK_ALL,
+ .background_dirty_ratio = -1,
+ .throttle_dirty_ratio = -1,
};

/*
@@ -785,6 +791,21 @@ static int update_flag(cpuset_flagbits_t
return 0;
}

+static int update_int(int *cs_int, char *buf, int min, int max)
+{
+ char *endp;
+ int val;
+
+ val = simple_strtol(buf, &endp, 10);
+ if (val < min || val > max)
+ return -EINVAL;
+
+ mutex_lock(&callback_mutex);
+ *cs_int = val;
+ mutex_unlock(&callback_mutex);
+ return 0;
+}
+
/*
* Frequency meter - How fast is some event occurring?
*
@@ -933,6 +954,8 @@ typedef enum {
FILE_MEMORY_PRESSURE,
FILE_SPREAD_PAGE,
FILE_SPREAD_SLAB,
+ FILE_THROTTLE_DIRTY_RATIO,
+ FILE_BACKGROUND_DIRTY_RATIO,
} cpuset_filetype_t;

static ssize_t cpuset_common_file_write(struct container *cont,
@@ -997,6 +1020,12 @@ static ssize_t cpuset_common_file_write(
retval = update_flag(CS_SPREAD_SLAB, cs, buffer);
cs->mems_generation = cpuset_mems_generation++;
break;
+ case FILE_BACKGROUND_DIRTY_RATIO:
+ retval = update_int(&cs->background_dirty_ratio, buffer, -1, 100);
+ break;
+ case FILE_THROTTLE_DIRTY_RATIO:
+ retval = update_int(&cs->throttle_dirty_ratio, buffer, -1, 100);
+ break;
default:
retval = -EINVAL;
goto out2;
@@ -1090,6 +1119,12 @@ static ssize_t cpuset_common_file_read(s
case FILE_SPREAD_SLAB:
*s++ = is_spread_slab(cs) ? '1' : '0';
break;
+ case FILE_BACKGROUND_DIRTY_RATIO:
+ s += sprintf(s, "%d", cs->background_dirty_ratio);
+ break;
+ case FILE_THROTTLE_DIRTY_RATIO:
+ s += sprintf(s, "%d", cs->throttle_dirty_ratio);
+ break;
default:
retval = -EINVAL;
goto out;
@@ -1173,6 +1208,20 @@ static struct cftype cft_spread_slab = {
.private = FILE_SPREAD_SLAB,
};

+static struct cftype cft_background_dirty_ratio = {
+ .name = "background_dirty_ratio",
+ .read = cpuset_common_file_read,
+ .write = cpuset_common_file_write,
+ .private = FILE_BACKGROUND_DIRTY_RATIO,
+};
+
+static struct cftype cft_throttle_dirty_ratio = {
+ .name = "throttle_dirty_ratio",
+ .read = cpuset_common_file_read,
+ .write = cpuset_common_file_write,
+ .private = FILE_THROTTLE_DIRTY_RATIO,
+};
+
static int cpuset_populate(struct container_subsys *ss, struct container *cont)
{
int err;
@@ -1193,6 +1242,10 @@ static int cpuset_populate(struct contai
return err;
if ((err = container_add_file(cont, ss, &cft_spread_slab)) < 0)
return err;
+ if ((err = container_add_file(cont, ss, &cft_background_dirty_ratio)) < 0)
+ return err;
+ if ((err = container_add_file(cont, ss, &cft_throttle_dirty_ratio)) < 0)
+ return err;
/* memory_pressure_enabled is in root cpuset only */
if (err == 0 && !cont->parent)
err = container_add_file(cont, ss,
@@ -1272,6 +1325,8 @@ static struct container_subsys_state *cp
cs->mems_allowed = NODE_MASK_NONE;
cs->mems_generation = cpuset_mems_generation++;
fmeter_init(&cs->fmeter);
+ cs->background_dirty_ratio = parent->background_dirty_ratio;
+ cs->throttle_dirty_ratio = parent->throttle_dirty_ratio;

cs->parent = parent;
number_of_cpusets++;
@@ -1755,8 +1810,30 @@ int cpuset_mem_spread_node(void)
}
EXPORT_SYMBOL_GPL(cpuset_mem_spread_node);

-#if MAX_NUMNODES > BITS_PER_LONG
+/*
+ * Determine the dirty ratios for the currently active cpuset
+ */
+void cpuset_get_current_ratios(int *background_ratio, int *throttle_ratio)
+{
+ int background = -1;
+ int throttle = -1;
+ struct task_struct *tsk = current;
+
+ task_lock(tsk);
+ background = task_cs(tsk)->background_dirty_ratio;
+ throttle = task_cs(tsk)->throttle_dirty_ratio;
+ task_unlock(tsk);

+ if (background == -1)
+ background = dirty_background_ratio;
+ if (throttle == -1)
+ throttle = vm_dirty_ratio;
+
+ *background_ratio = background;
+ *throttle_ratio = throttle;
+}
+
+#if MAX_NUMNODES > BITS_PER_LONG
/*
* Special functions for NUMA systems with a large number of nodes.
* The nodemask is pointed to from the address space structures.
diff -uprN -X 0/Documentation/dontdiff 5/mm/page-writeback.c 7/mm/page-writeback.c
--- 5/mm/page-writeback.c 2007-09-11 14:50:52.000000000 -0700
+++ 7/mm/page-writeback.c 2007-09-11 14:51:12.000000000 -0700
@@ -221,6 +221,7 @@ get_dirty_limits(struct dirty_limits *dl
/* Ensure that we return >= 0 */
if (available_memory <= 0)
available_memory = 1;
+ cpuset_get_current_ratios(&background_ratio, &dirty_ratio);
} else
#endif
{
@@ -231,17 +232,17 @@ get_dirty_limits(struct dirty_limits *dl
available_memory = determine_dirtyable_memory();
nr_mapped = global_page_state(NR_FILE_MAPPED) +
global_page_state(NR_ANON_PAGES);
+ dirty_ratio = vm_dirty_ratio;
+ background_ratio = dirty_background_ratio;
}

unmapped_ratio = 100 - (nr_mapped * 100 / available_memory);
- dirty_ratio = vm_dirty_ratio;
if (dirty_ratio > unmapped_ratio / 2)
dirty_ratio = unmapped_ratio / 2;

if (dirty_ratio < 5)
dirty_ratio = 5;

- background_ratio = dirty_background_ratio;
if (background_ratio >= dirty_ratio)
background_ratio = dirty_ratio / 2;

-
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