[PATCH 3/5] writeback: nr_dirtied and nr_written in /proc/vmstat

[PATCH 3/5] writeback: nr_dirtied and nr_written in /proc/vmstat

[Michael Rubin]

To help developers and applications gain visibility into writeback
behaviour adding two entries to vm_stat_items and /proc/vmstat. This
will allow us to track the "written" and "dirtied" counts.

   # grep nr_dirtied /proc/vmstat
   nr_dirtied 3747
   # grep nr_written /proc/vmstat
   nr_written 3618

Signed-off-by: Michael Rubin <mrubin@google.com>
---
 include/linux/mmzone.h |    2 ++
 mm/page-writeback.c    |    2 ++
 mm/vmstat.c            |    3 +++
 3 files changed, 7 insertions(+), 0 deletions(-)

diff --git a/include/linux/mmzone.h b/include/linux/mmzone.h
index 6e6e626..bd6c7fc 100644
--- a/include/linux/mmzone.h
+++ b/include/linux/mmzone.h
@@ -104,6 +104,8 @@ enum zone_stat_item {
 	NR_ISOLATED_ANON,	/* Temporary isolated pages from anon lru */
 	NR_ISOLATED_FILE,	/* Temporary isolated pages from file lru */
 	NR_SHMEM,		/* shmem pages (included tmpfs/GEM pages) */
+	NR_DIRTIED,		/* page dirtyings since bootup */
+	NR_WRITTEN,		/* page writings since bootup */
 #ifdef CONFIG_NUMA
 	NUMA_HIT,		/* allocated in intended node */
 	NUMA_MISS,		/* allocated in non intended node */
diff --git a/mm/page-writeback.c b/mm/page-writeback.c
index ae5f5d5..79feaa0 100644
--- a/mm/page-writeback.c
+++ b/mm/page-writeback.c
@@ -1126,6 +1126,7 @@ void account_page_dirtied(struct page *page, struct address_space *mapping)
 {
 	if (mapping_cap_account_dirty(mapping)) {
 		__inc_zone_page_state(page, NR_FILE_DIRTY);
+		__inc_zone_page_state(page, NR_DIRTIED);
 		__inc_bdi_stat(mapping->backing_dev_info, BDI_RECLAIMABLE);
 		task_dirty_inc(current);
 		task_io_account_write(PAGE_CACHE_SIZE);
@@ -1141,6 +1142,7 @@ EXPORT_SYMBOL(account_page_dirtied);
 void account_page_writeback(struct page *page)
 {
 	inc_zone_page_state(page, NR_WRITEBACK);
+	inc_zone_page_state(page, NR_WRITTEN);
 }
 EXPORT_SYMBOL(account_page_writeback);
 
diff --git a/mm/vmstat.c b/mm/vmstat.c
index f389168..d448ef4 100644
--- a/mm/vmstat.c
+++ b/mm/vmstat.c
@@ -732,6 +732,9 @@ static const char * const vmstat_text[] = {
 	"nr_isolated_anon",
 	"nr_isolated_file",
 	"nr_shmem",
+	"nr_dirtied",
+	"nr_written",
+
 #ifdef CONFIG_NUMA
 	"numa_hit",
 	"numa_miss",
-- 
1.7.1

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[PATCH 4/5] writeback: Adding /sys/devices/system/node/<node>/vmstat

[Michael Rubin]

For NUMA node systems it is important to have visibility in memory
characteristics. Two of the /proc/vmstat values "nr_written" and
"nr_dirtied" are added here.

	# cat /sys/devices/system/node/node20/vmstat
	nr_written 0
	nr_dirtied 0

Signed-off-by: Michael Rubin <mrubin@google.com>
---
 drivers/base/node.c |   14 ++++++++++++++
 1 files changed, 14 insertions(+), 0 deletions(-)

diff --git a/drivers/base/node.c b/drivers/base/node.c
index 2872e86..2832ebd 100644
--- a/drivers/base/node.c
+++ b/drivers/base/node.c
@@ -160,6 +160,18 @@ static ssize_t node_read_numastat(struct sys_device * dev,
 }
 static SYSDEV_ATTR(numastat, S_IRUGO, node_read_numastat, NULL);
 
+static ssize_t node_read_vmstat(struct sys_device *dev,
+				struct sysdev_attribute *attr, char *buf)
+{
+	int nid = dev->id;
+	return sprintf(buf,
+		"nr_written %lu\n"
+		"nr_dirtied %lu\n",
+		node_page_state(nid, NR_WRITTEN),
+		node_page_state(nid, NR_DIRTIED));
+}
+static SYSDEV_ATTR(vmstat, S_IRUGO, node_read_vmstat, NULL);
+
 static ssize_t node_read_distance(struct sys_device * dev,
 			struct sysdev_attribute *attr, char * buf)
 {
@@ -243,6 +255,7 @@ int register_node(struct node *node, int num, struct node *parent)
 		sysdev_create_file(&node->sysdev, &attr_meminfo);
 		sysdev_create_file(&node->sysdev, &attr_numastat);
 		sysdev_create_file(&node->sysdev, &attr_distance);
+		sysdev_create_file(&node->sysdev, &attr_vmstat);
 
 		scan_unevictable_register_node(node);
 
@@ -267,6 +280,7 @@ void unregister_node(struct node *node)
 	sysdev_remove_file(&node->sysdev, &attr_meminfo);
 	sysdev_remove_file(&node->sysdev, &attr_numastat);
 	sysdev_remove_file(&node->sysdev, &attr_distance);
+	sysdev_remove_file(&node->sysdev, &attr_vmstat);
 
 	scan_unevictable_unregister_node(node);
 	hugetlb_unregister_node(node);		/* no-op, if memoryless node */
-- 
1.7.1

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[PATCH 0/5] writeback: kernel visibility

[Michael Rubin]

Patch #1 sets up some helper functions for account_page_dirty and fixes
a bug in ceph

Patch #2 sets up some helper functions for account_page_writeback

Patch #3 adds writeback visibility in /proc/vmstat

To help developers and applications gain visibility into writeback
behaviour this patch adds two counters to /proc/vmstat.

  # grep nr_dirtied /proc/vmstat
  nr_dirtied 3747
  # grep nr_written /proc/vmstat
  nr_written 3618

These entries allow user apps to understand writeback behaviour over
time and learn how it is impacting their performance. Currently there
is no way to inspect dirty and writeback speed over time. It's not
possible for nr_dirty/nr_writeback.

These entries are necessary to give visibility into writeback
behaviour. We have /proc/diskstats which lets us understand the io in
the block layer. We have blktrace for more in depth understanding. We have
e2fsprogs and debugsfs to give insight into the file systems behaviour,
but we don't offer our users the ability understand what writeback is
doing. There is no way to know how active it is over the whole system,
if it's falling behind or to quantify it's efforts. With these values
exported users can easily see how much data applications are sending
through writeback and also at what rates writeback is processing this
data. Comparing the rates of change between the two allow developers
to see when writeback is not able to keep up with incoming traffic and
the rate of dirty memory being sent to the IO back end. This allows
folks to understand their io workloads and track kernel issues. Non
kernel engineers at Google often use these counters to solve puzzling
performance problems.

Patch #4 adds a pernode vmstat file with nr_dirtied and nr_written

Patch #5 add writeback thresholds to /proc/vmstat

Currently these values are in debugfs. But they should be promoted to
/proc since they are useful for developers who are writing databases
and file servers and are not debugging the kernel.

The output is as below:

 # grep threshold /proc/vmstat
 nr_pages_dirty_threshold 409111
 nr_pages_dirty_background_threshold 818223

Michael Rubin (5):
  mm: exporting account_page_dirty
  mm: account_page_writeback added
  writeback: nr_dirtied and nr_written in /proc/vmstat
  writeback: Adding /sys/devices/system/node/<node>/vmstat
  writeback: Reporting dirty thresholds in /proc/vmstat

 drivers/base/node.c    |   14 ++++++++++++++
 fs/ceph/addr.c         |    8 +-------
 fs/nilfs2/segment.c    |    2 +-
 include/linux/mm.h     |    1 +
 include/linux/mmzone.h |    2 ++
 mm/page-writeback.c    |   16 +++++++++++++++-
 mm/vmstat.c            |   42 ++++++++++++++++++++++++++++--------------
 7 files changed, 62 insertions(+), 23 deletions(-)

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[PATCH 4/5] writeback: Adding /sys/devices/system/node/<node>/vmstat

[Michael Rubin]

For NUMA node systems it is important to have visibility in memory
characteristics. Two of the /proc/vmstat values "nr_written" and
"nr_dirtied" are added here.

	# cat /sys/devices/system/node/node20/vmstat
	nr_written 0
	nr_dirtied 0

Signed-off-by: Michael Rubin <mrubin@google.com>
Reviewed-by: Wu Fengguang <fengguang.wu@intel.com>
---
 drivers/base/node.c |   14 ++++++++++++++
 1 files changed, 14 insertions(+), 0 deletions(-)

diff --git a/drivers/base/node.c b/drivers/base/node.c
index 2872e86..6aaccd9 100644
--- a/drivers/base/node.c
+++ b/drivers/base/node.c
@@ -160,6 +160,18 @@ static ssize_t node_read_numastat(struct sys_device * dev,
 }
 static SYSDEV_ATTR(numastat, S_IRUGO, node_read_numastat, NULL);
 
+static ssize_t node_read_vmstat(struct sys_device *dev,
+				struct sysdev_attribute *attr, char *buf)
+{
+	int nid = dev->id;
+	return sprintf(buf,
+		"nr_written %lu\n"
+		"nr_dirtied %lu\n",
+		node_page_state(nid, NR_WRITTEN),
+		node_page_state(nid, NR_FILE_DIRTIED));
+}
+static SYSDEV_ATTR(vmstat, S_IRUGO, node_read_vmstat, NULL);
+
 static ssize_t node_read_distance(struct sys_device * dev,
 			struct sysdev_attribute *attr, char * buf)
 {
@@ -243,6 +255,7 @@ int register_node(struct node *node, int num, struct node *parent)
 		sysdev_create_file(&node->sysdev, &attr_meminfo);
 		sysdev_create_file(&node->sysdev, &attr_numastat);
 		sysdev_create_file(&node->sysdev, &attr_distance);
+		sysdev_create_file(&node->sysdev, &attr_vmstat);
 
 		scan_unevictable_register_node(node);
 
@@ -267,6 +280,7 @@ void unregister_node(struct node *node)
 	sysdev_remove_file(&node->sysdev, &attr_meminfo);
 	sysdev_remove_file(&node->sysdev, &attr_numastat);
 	sysdev_remove_file(&node->sysdev, &attr_distance);
+	sysdev_remove_file(&node->sysdev, &attr_vmstat);
 
 	scan_unevictable_unregister_node(node);
 	hugetlb_unregister_node(node);		/* no-op, if memoryless node */
-- 
1.7.1

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[PATCH 0/5] writeback: kernel visibility

[Michael Rubin]

Patch #1 sets up some helper functions for account_page_dirty and fixes
a bug in ceph

Patch #2 sets up some helper functions for account_page_writeback

Patch #3 adds writeback visibility in /proc/vmstat

To help developers and applications gain visibility into writeback
behaviour this patch adds two counters to /proc/vmstat.

  # grep nr_dirtied /proc/vmstat
  nr_dirtied 3747
  # grep nr_written /proc/vmstat
  nr_written 3618

These entries allow user apps to understand writeback behaviour over
time and learn how it is impacting their performance. Currently there
is no way to inspect dirty and writeback speed over time. It's not
possible for nr_dirty/nr_writeback.

These entries are necessary to give visibility into writeback
behaviour. We have /proc/diskstats which lets us understand the io in
the block layer. We have blktrace for more in depth understanding. We have
e2fsprogs and debugsfs to give insight into the file systems behaviour,
but we don't offer our users the ability understand what writeback is
doing. There is no way to know how active it is over the whole system,
if it's falling behind or to quantify it's efforts. With these values
exported users can easily see how much data applications are sending
through writeback and also at what rates writeback is processing this
data. Comparing the rates of change between the two allow developers
to see when writeback is not able to keep up with incoming traffic and
the rate of dirty memory being sent to the IO back end. This allows
folks to understand their io workloads and track kernel issues. Non
kernel engineers at Google often use these counters to solve puzzling
performance problems.

Patch #4 adds a pernode vmstat file with nr_dirtied and nr_written

Patch #5 add writeback thresholds to /proc/vmstat

Currently these values are in debugfs. But they should be promoted to
/proc since they are useful for developers who are writing databases
and file servers and are not debugging the kernel.

The output is as below:

 # grep threshold /proc/vmstat
 nr_pages_dirty_threshold 409111
 nr_pages_dirty_background_threshold 818223

Michael Rubin (5):
  mm: exporting account_page_dirty
  mm: account_page_writeback added
  writeback: nr_dirtied and nr_written in /proc/vmstat
  writeback: Adding /sys/devices/system/node/<node>/vmstat
  writeback: Reporting dirty thresholds in /proc/vmstat

 drivers/base/node.c    |   14 ++++++++++++++
 fs/ceph/addr.c         |    8 +-------
 fs/nilfs2/segment.c    |    2 +-
 include/linux/mm.h     |    1 +
 include/linux/mmzone.h |    4 ++++
 mm/page-writeback.c    |   16 +++++++++++++++-
 mm/vmstat.c            |    7 +++++++
 7 files changed, 43 insertions(+), 9 deletions(-)

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[PATCH 4/5] writeback: Adding /sys/devices/system/node/<node>/vmstat

[Michael Rubin]

For NUMA node systems it is important to have visibility in memory
characteristics. Two of the /proc/vmstat values "nr_cleaned" and
"nr_dirtied" are added here.

	# cat /sys/devices/system/node/node20/vmstat
	nr_cleaned 0
	nr_dirtied 0

Signed-off-by: Michael Rubin <mrubin@google.com>
---
 drivers/base/node.c |   14 ++++++++++++++
 1 files changed, 14 insertions(+), 0 deletions(-)

diff --git a/drivers/base/node.c b/drivers/base/node.c
index 2872e86..6aaccd9 100644
--- a/drivers/base/node.c
+++ b/drivers/base/node.c
@@ -160,6 +160,18 @@ static ssize_t node_read_numastat(struct sys_device * dev,
 }
 static SYSDEV_ATTR(numastat, S_IRUGO, node_read_numastat, NULL);
 
+static ssize_t node_read_vmstat(struct sys_device *dev,
+				struct sysdev_attribute *attr, char *buf)
+{
+	int nid = dev->id;
+	return sprintf(buf,
+		"nr_written %lu\n"
+		"nr_dirtied %lu\n",
+		node_page_state(nid, NR_WRITTEN),
+		node_page_state(nid, NR_FILE_DIRTIED));
+}
+static SYSDEV_ATTR(vmstat, S_IRUGO, node_read_vmstat, NULL);
+
 static ssize_t node_read_distance(struct sys_device * dev,
 			struct sysdev_attribute *attr, char * buf)
 {
@@ -243,6 +255,7 @@ int register_node(struct node *node, int num, struct node *parent)
 		sysdev_create_file(&node->sysdev, &attr_meminfo);
 		sysdev_create_file(&node->sysdev, &attr_numastat);
 		sysdev_create_file(&node->sysdev, &attr_distance);
+		sysdev_create_file(&node->sysdev, &attr_vmstat);
 
 		scan_unevictable_register_node(node);
 
@@ -267,6 +280,7 @@ void unregister_node(struct node *node)
 	sysdev_remove_file(&node->sysdev, &attr_meminfo);
 	sysdev_remove_file(&node->sysdev, &attr_numastat);
 	sysdev_remove_file(&node->sysdev, &attr_distance);
+	sysdev_remove_file(&node->sysdev, &attr_vmstat);
 
 	scan_unevictable_unregister_node(node);
 	hugetlb_unregister_node(node);		/* no-op, if memoryless node */
-- 
1.7.1

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Re: [PATCH 4/5] writeback: Adding /sys/devices/system/node/<node>/vmstat

[Wu Fengguang]

On Mon, Sep 13, 2010 at 04:30:39AM +0800, Michael Rubin wrote:
> For NUMA node systems it is important to have visibility in memory
> characteristics. Two of the /proc/vmstat values "nr_cleaned" and

s/nr_cleaned/nr_written/

> "nr_dirtied" are added here.
> 
> 	# cat /sys/devices/system/node/node20/vmstat
> 	nr_cleaned 0

ditto

> 	nr_dirtied 0
> 
> Signed-off-by: Michael Rubin <mrubin@google.com>

Reviewed-by: Wu Fengguang <fengguang.wu@intel.com>

> +static ssize_t node_read_vmstat(struct sys_device *dev,
> +				struct sysdev_attribute *attr, char *buf)
> +{
> +	int nid = dev->id;
> +	return sprintf(buf,
> +		"nr_written %lu\n"
> +		"nr_dirtied %lu\n",
> +		node_page_state(nid, NR_WRITTEN),
> +		node_page_state(nid, NR_FILE_DIRTIED));
> +}

Do you have plan to port more vmstat_text[] items? :)

Thanks,
Fengguang

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Re: [PATCH 4/5] writeback: Adding /sys/devices/system/node/<node>/vmstat

[Michael Rubin]

On Sun, Sep 12, 2010 at 8:02 PM, Wu Fengguang <fengguang.wu@intel.com> wrote:
> Do you have plan to port more vmstat_text[] items? :)

Yes. I feel bound to do it after all your help. :-)
I may need a few weeks to resolve some other issues but I can get back to this.

mrubin

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