Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1757898Ab0HCWTv (ORCPT ); Tue, 3 Aug 2010 18:19:51 -0400 Received: from smtp-out.google.com ([74.125.121.35]:33055 "EHLO smtp-out.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752192Ab0HCWTt (ORCPT ); Tue, 3 Aug 2010 18:19:49 -0400 DomainKey-Signature: a=rsa-sha1; s=beta; d=google.com; c=nofws; q=dns; h=from:to:cc:subject:date:message-id:x-mailer:in-reply-to:references; b=ABkwQBdv+PkdHD/8l9Q7LXLPDlZ1EPlxLyi1mNWzgeMKmheRjyYvEPAOGJ1GM4sJY biFMkBkncjvved9puVp5g== From: Michael Rubin To: linux-kernel@vger.kernel.org, linux-fsdevel@vger.kernel.org, linux-mm@kvack.org Cc: jack@suse.cz, akpm@linux-foundation.org, david@fromorbit.com, hch@lst.de, axboe@kernel.dk, Michael Rubin Subject: [PATCH 2/2] writeback: Adding four read-only files to /proc/sys/vm Date: Tue, 3 Aug 2010 15:19:09 -0700 Message-Id: <1280873949-20460-3-git-send-email-mrubin@google.com> X-Mailer: git-send-email 1.7.1 In-Reply-To: <1280873949-20460-1-git-send-email-mrubin@google.com> References: <1280873949-20460-1-git-send-email-mrubin@google.com> Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 13093 Lines: 391 To help developers and applications gain visibility into writeback behaviour adding four read only sysctl files into /proc/sys/vm. These files allow user apps to understand writeback behaviour over time and learn how it is impacting their performance. # cat /proc/sys/vm/pages_dirtied 3747 # cat /proc/sys/vm/pages_entered_writeback 3618 # cat /proc/sys/vm/dirty_threshold_kbytes 816673 # cat /proc/sys/vm/dirty_background_threshold_kbytes 408336 Documentation/vm.txt has been updated. 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 Signed-off-by: Michael Rubin --- Documentation/sysctl/vm.txt | 41 +++++++++++++++++++++++++--- drivers/base/node.c | 14 +++++++++ include/linux/mmzone.h | 2 + include/linux/writeback.h | 17 +++++++++++ kernel/sysctl.c | 28 +++++++++++++++++++ mm/page-writeback.c | 64 +++++++++++++++++++++++++++++++++++++++---- mm/vmstat.c | 2 + 7 files changed, 158 insertions(+), 10 deletions(-) diff --git a/Documentation/sysctl/vm.txt b/Documentation/sysctl/vm.txt index 5fdbb61..cfb640d 100644 --- a/Documentation/sysctl/vm.txt +++ b/Documentation/sysctl/vm.txt @@ -22,9 +22,11 @@ Currently, these files are in /proc/sys/vm: - compact_memory - dirty_background_bytes - dirty_background_ratio +- dirty_background_threshold_kbytes - dirty_bytes - dirty_expire_centisecs - dirty_ratio +- dirty_threshold_kbytes - dirty_writeback_centisecs - drop_caches - extfrag_threshold @@ -50,6 +52,8 @@ Currently, these files are in /proc/sys/vm: - overcommit_memory - overcommit_ratio - page-cluster +- pages_dirtied +- pages_entered_writeback - panic_on_oom - percpu_pagelist_fraction - stat_interval @@ -92,6 +96,15 @@ the pdflush background writeback daemon will start writing out dirty data. ============================================================== +dirty_background_threshold_kbytes + +Contains the exact amount of dirty memory memory in kbytes the kernel +uses to trigger the background writeout daemon will start writing out +dirty data. This value depends on memory state, dirty_background_ratio +and/or dirty_background_bytes. This value is read-only. + +============================================================== + dirty_bytes Contains the amount of dirty memory at which a process generating disk writes @@ -123,6 +136,15 @@ data. ============================================================== +dirty_threshold_kbytes + +Contains the exact amount of dirty memory in kilobytes that the kernel +uses to decide when a process which is generating disk writes will itself +start writing out data. This value depends on memory state, dirty_ratio +and/or dirty_bytes. This value is read-only. + +============================================================== + dirty_writeback_centisecs The pdflush writeback daemons will periodically wake up and write `old' data @@ -425,10 +447,7 @@ See Documentation/vm/hugetlbpage.txt nr_pdflush_threads The current number of pdflush threads. This value is read-only. -The value changes according to the number of dirty pages in the system. - -When necessary, additional pdflush threads are created, one per second, up to -nr_pdflush_threads_max. +This value is obsolete. ============================================================== @@ -580,8 +599,22 @@ The default value is three (eight pages at a time). There may be some small benefits in tuning this to a different value if your workload is swap-intensive. + +============================================================= + +pages_dirtied + +Number of pages that have ever been dirtied since boot. +This value is read-only. + ============================================================= +pages_entered_writeback + +Number of pages that have been moved from dirty to writeback since boot. +This is only a count of file pages. This value is read-only. + +============================================================= panic_on_oom This enables or disables panic on out-of-memory feature. diff --git a/drivers/base/node.c b/drivers/base/node.c index 2bdd8a9..b321d32 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)); +} +static SYSDEV_ATTR(writebackstat, S_IRUGO, node_read_writebackstat, 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_writebackstat); 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); 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 b4d109e..c0cd2bd 100644 --- a/include/linux/mmzone.h +++ b/include/linux/mmzone.h @@ -112,6 +112,8 @@ enum zone_stat_item { NUMA_LOCAL, /* allocation from local node */ NUMA_OTHER, /* allocation from other node */ #endif + NR_PAGES_ENTERED_WRITEBACK, /* number of times pages enter writeback */ + NR_FILE_PAGES_DIRTIED, /* number of times pages get dirtied */ NR_VM_ZONE_STAT_ITEMS }; /* diff --git a/include/linux/writeback.h b/include/linux/writeback.h index c24eca7..b3b7038 100644 --- a/include/linux/writeback.h +++ b/include/linux/writeback.h @@ -99,6 +99,10 @@ extern int dirty_background_ratio; extern unsigned long dirty_background_bytes; extern int vm_dirty_ratio; extern unsigned long vm_dirty_bytes; +extern unsigned long vm_pages_dirtied; +extern unsigned long vm_pages_entered_writeback; +extern unsigned long vm_dirty_threshold; +extern unsigned long vm_bg_threshold; extern unsigned int dirty_writeback_interval; extern unsigned int dirty_expire_interval; extern int vm_highmem_is_dirtyable; @@ -120,6 +124,19 @@ extern int dirty_bytes_handler(struct ctl_table *table, int write, void __user *buffer, size_t *lenp, loff_t *ppos); +extern int pages_dirtied_handler(struct ctl_table *table, int write, + void __user *buffer, size_t *lenp, + loff_t *ppos); +extern int pages_entered_writeback_handler(struct ctl_table *table, int write, + void __user *buffer, size_t *lenp, + loff_t *ppos); +extern int dirty_threshold_handler(struct ctl_table *table, int write, + void __user *buffer, size_t *lenp, + loff_t *ppos); +extern int bg_threshold_handler(struct ctl_table *table, int write, + void __user *buffer, size_t *lenp, + loff_t *ppos); + struct ctl_table; int dirty_writeback_centisecs_handler(struct ctl_table *, int, void __user *, size_t *, loff_t *); diff --git a/kernel/sysctl.c b/kernel/sysctl.c index d24f761..8dcec17 100644 --- a/kernel/sysctl.c +++ b/kernel/sysctl.c @@ -1053,6 +1053,34 @@ static struct ctl_table vm_table[] = { .proc_handler = proc_dointvec, }, { + .procname = "pages_dirtied", + .data = &vm_pages_dirtied, + .maxlen = sizeof(vm_pages_dirtied), + .mode = 0444 /* read-only */, + .proc_handler = pages_dirtied_handler, + }, + { + .procname = "pages_entered_writeback", + .data = &vm_pages_entered_writeback, + .maxlen = sizeof(vm_pages_entered_writeback), + .mode = 0444 /* read-only */, + .proc_handler = pages_entered_writeback_handler, + }, + { + .procname = "dirty_threshold_kbytes", + .data = &vm_dirty_threshold, + .maxlen = sizeof(vm_dirty_threshold), + .mode = 0444 /* read-only */, + .proc_handler = dirty_threshold_handler, + }, + { + .procname = "dirty_background_threshold_kbytes", + .data = &vm_bg_threshold, + .maxlen = sizeof(vm_bg_threshold), + .mode = 0444 /* read-only */, + .proc_handler = bg_threshold_handler, + }, + { .procname = "nr_pdflush_threads", .data = &nr_pdflush_threads, .maxlen = sizeof nr_pdflush_threads, diff --git a/mm/page-writeback.c b/mm/page-writeback.c index b8e7b3b..84e3e2e 100644 --- a/mm/page-writeback.c +++ b/mm/page-writeback.c @@ -95,6 +95,20 @@ unsigned int dirty_writeback_interval = 5 * 100; /* centiseconds */ */ unsigned int dirty_expire_interval = 30 * 100; /* centiseconds */ + +/* + * Number of pages dirtied and entered writeback state + */ + +unsigned long vm_pages_dirtied; +unsigned long vm_pages_entered_writeback; + +/* + * Dirty thresholds for export + */ +unsigned long vm_dirty_threshold; +unsigned long vm_bg_threshold; + /* * Flag that makes the machine dump writes/reads and block dirtyings. */ @@ -196,7 +210,6 @@ int dirty_ratio_handler(struct ctl_table *table, int write, return ret; } - int dirty_bytes_handler(struct ctl_table *table, int write, void __user *buffer, size_t *lenp, loff_t *ppos) @@ -212,6 +225,45 @@ int dirty_bytes_handler(struct ctl_table *table, int write, return ret; } +int pages_dirtied_handler(struct ctl_table *table, int write, + void __user *buffer, size_t *lenp, + loff_t *ppos) +{ + vm_pages_dirtied = global_page_state(NR_FILE_PAGES_DIRTIED); + return proc_doulongvec_minmax(table, write, buffer, lenp, ppos); +} + +int pages_entered_writeback_handler(struct ctl_table *table, int write, + void __user *buffer, size_t *lenp, + loff_t *ppos) +{ + vm_pages_entered_writeback = + global_page_state(NR_PAGES_ENTERED_WRITEBACK); + return proc_doulongvec_minmax(table, write, buffer, lenp, ppos); +} + +#define K(pages) ((pages) << (PAGE_SHIFT - 10)) + +int dirty_threshold_handler(struct ctl_table *table, int write, + void __user *buffer, size_t *lenp, + loff_t *ppos) +{ + unsigned long bg_thresh, dirty_thresh; + get_dirty_limits(&bg_thresh, &dirty_thresh, NULL, NULL); + vm_dirty_threshold = K(dirty_thresh); + return proc_doulongvec_minmax(table, write, buffer, lenp, ppos); +} + +int bg_threshold_handler(struct ctl_table *table, int write, + void __user *buffer, size_t *lenp, + loff_t *ppos) +{ + unsigned long bg_thresh, dirty_thresh; + get_dirty_limits(&bg_thresh, &dirty_thresh, NULL, NULL); + vm_bg_threshold = K(bg_thresh); + return proc_doulongvec_minmax(table, write, buffer, lenp, ppos); +} + /* * Increment the BDI's writeout completion count and the global writeout * completion count. Called from test_clear_page_writeback(). @@ -1091,6 +1143,7 @@ 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_bdi_stat(mapping->backing_dev_info, BDI_RECLAIMABLE); task_dirty_inc(current); task_io_account_write(PAGE_CACHE_SIZE); @@ -1103,15 +1156,15 @@ EXPORT_SYMBOL(account_page_dirtied); * NOTE: Unlike account_page_dirtied this does not rely on being atomic * wrt interrupts. */ - void account_page_writeback(struct page *page, struct address_space *mapping) { - if (mapping_cap_account_dirty(mapping)) + if (mapping_cap_account_dirty(mapping)) { inc_zone_page_state(page, NR_WRITEBACK); + inc_zone_page_state(page, NR_PAGES_ENTERED_WRITEBACK); + } } EXPORT_SYMBOL(account_page_writeback); - /* * For address_spaces which do not use buffers. Just tag the page as dirty in * its radix tree. @@ -1347,9 +1400,8 @@ int test_set_page_writeback(struct page *page) ret = TestSetPageWriteback(page); } if (!ret) - inc_zone_page_state(page, NR_WRITEBACK); + account_page_writeback(page, mapping); return ret; - } EXPORT_SYMBOL(test_set_page_writeback); diff --git a/mm/vmstat.c b/mm/vmstat.c index 7759941..e177a40 100644 --- a/mm/vmstat.c +++ b/mm/vmstat.c @@ -740,6 +740,8 @@ static const char * const vmstat_text[] = { "numa_local", "numa_other", #endif + "nr_pages_entered_writeback", + "nr_file_pages_dirtied", #ifdef CONFIG_VM_EVENT_COUNTERS "pgpgin", -- 1.7.1 -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/