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Message-ID: <20100820100855.GC8440@localhost>
Date: Fri, 20 Aug 2010 18:08:56 +0800
From: Wu Fengguang <fengguang.wu@...el.com>
To: Michael Rubin <mrubin@...gle.com>
Cc: "linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
"linux-fsdevel@...r.kernel.org" <linux-fsdevel@...r.kernel.org>,
"linux-mm@...ck.org" <linux-mm@...ck.org>,
"jack@...e.cz" <jack@...e.cz>, "riel@...hat.com" <riel@...hat.com>,
"akpm@...ux-foundation.org" <akpm@...ux-foundation.org>,
"david@...morbit.com" <david@...morbit.com>,
"npiggin@...nel.dk" <npiggin@...nel.dk>, "hch@....de" <hch@....de>,
"axboe@...nel.dk" <axboe@...nel.dk>
Subject: Re: [PATCH 3/4] writeback: nr_dirtied and nr_entered_writeback in
/proc/vmstat
On Fri, Aug 20, 2010 at 05:31:28PM +0800, Michael Rubin wrote:
> To help developers and applications gain visibility into writeback
> behaviour adding two entries to /proc/vmstat.
>
> # grep nr_dirtied /proc/vmstat
> nr_dirtied 3747
> # grep nr_entered_writeback /proc/vmstat
> nr_entered_writeback 3618
How about the names nr_dirty_accumulated and nr_writeback_accumulated?
It seems more consistent, for both the interface and code (see below).
I'm not really sure though.
> In order to track the "cleaned" and "dirtied" counts we added two
> vm_stat_items. Per memory node stats have been added also. So we can
> see per node granularity:
>
> # cat /sys/devices/system/node/node20/writebackstat
> Node 20 pages_writeback: 0 times
> Node 20 pages_dirtied: 0 times
I'd prefer the name "vmstat" over "writebackstat", and propose to
migrate items from /proc/zoneinfo over time. zoneinfo is a terrible
interface for scripting.
Also, are there meaningful usage of per-node writeback stats?
The numbers are naturally per-bdi ones instead. But if we plan to
expose them for each bdi, this patch will need to be implemented
vastly differently.
> Signed-off-by: Michael Rubin <mrubin@...gle.com>
> ---
> drivers/base/node.c | 14 ++++++++++++++
> include/linux/mmzone.h | 2 ++
> mm/page-writeback.c | 2 ++
> mm/vmstat.c | 3 +++
> 4 files changed, 21 insertions(+), 0 deletions(-)
>
> diff --git a/drivers/base/node.c b/drivers/base/node.c
> index 2872e86..2d05421 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_writebackstat(struct sys_device *dev,
> + struct sysdev_attribute *attr, char *buf)
> +{
> + int nid = dev->id;
> + return sprintf(buf,
> + "Node %d pages_writeback: %lu times\n"
> + "Node %d pages_dirtied: %lu times\n",
> + nid, node_page_state(nid, NR_PAGES_ENTERED_WRITEBACK),
> + nid, node_page_state(nid, NR_FILE_PAGES_DIRTIED));
nid, node_page_state(nid, NR_WRITEBACK_ACCUMULATED),
nid, node_page_state(nid, NR_FILE_DIRTY_ACCUMULATED));
> +}
> +static SYSDEV_ATTR(writebackstat, S_IRUGO, node_read_writebackstat, NULL);
> +
s/writebackstat/vmstat/
> 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_writebackstat);
ditto
s/writebackstat/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_writebackstat);
ditto
s/writebackstat/vmstat/
> scan_unevictable_unregister_node(node);
> hugetlb_unregister_node(node); /* no-op, if memoryless node */
> diff --git a/include/linux/mmzone.h b/include/linux/mmzone.h
> index 6e6e626..fe4e6dd 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_FILE_PAGES_DIRTIED, /* number of times pages get dirtied */
> + NR_PAGES_ENTERED_WRITEBACK, /* number of times pages enter writeback */
NR_FILE_DIRTY_ACCUMULATED, /* number of times pages get dirtied */
NR_WRITEBACK_ACCUMULATED, /* number of times pages enter writeback */
> #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..1b1763c 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_FILE_PAGES_DIRTIED);
__inc_zone_page_state(page, NR_FILE_DIRTY_ACCUMULATED);
> __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_PAGES_ENTERED_WRITEBACK);
inc_zone_page_state(page, NR_WRITEBACK_ACCUMULATED);
> }
> EXPORT_SYMBOL(account_page_writeback);
>
> diff --git a/mm/vmstat.c b/mm/vmstat.c
> index f389168..073a496 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_entered_writeback",
"nr_dirty_accumulated",
"nr_writeback_accumulated",
> #ifdef CONFIG_NUMA
> "numa_hit",
> "numa_miss",
> --
> 1.7.1
--
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