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author | Hugh Dickins <hugh.dickins@tiscali.co.uk> | 2009-09-22 00:02:11 (GMT) |
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committer | Linus Torvalds <torvalds@linux-foundation.org> | 2009-09-22 14:17:32 (GMT) |
commit | 473b0ce4d13ee77925a7062e25dea0d16a91f654 (patch) | |
tree | 965433f77af7ddce5d9911e353e13af6db9ea311 /mm | |
parent | e178dfde3952192cf44eeb0612882f01fc96c0a9 (diff) | |
download | linux-fsl-qoriq-473b0ce4d13ee77925a7062e25dea0d16a91f654.tar.xz |
ksm: pages_unshared and pages_volatile
The pages_shared and pages_sharing counts give a good picture of how
successful KSM is at sharing; but no clue to how much wasted work it's
doing to get there. Add pages_unshared (count of unique pages waiting
in the unstable tree, hoping to find a mate) and pages_volatile.
pages_volatile is harder to define. It includes those pages changing
too fast to get into the unstable tree, but also whatever other edge
conditions prevent a page getting into the trees: a high value may
deserve investigation. Don't try to calculate it from the various
conditions: it's the total of rmap_items less those accounted for.
Also show full_scans: the number of completed scans of everything
registered in the mm list.
The locking for all these counts is simply ksm_thread_mutex.
Signed-off-by: Hugh Dickins <hugh.dickins@tiscali.co.uk>
Acked-by: Izik Eidus <ieidus@redhat.com>
Acked-by: Andrea Arcangeli <aarcange@redhat.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Diffstat (limited to 'mm')
-rw-r--r-- | mm/ksm.c | 52 |
1 files changed, 51 insertions, 1 deletions
@@ -155,6 +155,12 @@ static unsigned long ksm_pages_shared; /* The number of page slots additionally sharing those nodes */ static unsigned long ksm_pages_sharing; +/* The number of nodes in the unstable tree */ +static unsigned long ksm_pages_unshared; + +/* The number of rmap_items in use: to calculate pages_volatile */ +static unsigned long ksm_rmap_items; + /* Limit on the number of unswappable pages used */ static unsigned long ksm_max_kernel_pages; @@ -204,11 +210,17 @@ static void __init ksm_slab_free(void) static inline struct rmap_item *alloc_rmap_item(void) { - return kmem_cache_zalloc(rmap_item_cache, GFP_KERNEL); + struct rmap_item *rmap_item; + + rmap_item = kmem_cache_zalloc(rmap_item_cache, GFP_KERNEL); + if (rmap_item) + ksm_rmap_items++; + return rmap_item; } static inline void free_rmap_item(struct rmap_item *rmap_item) { + ksm_rmap_items--; rmap_item->mm = NULL; /* debug safety */ kmem_cache_free(rmap_item_cache, rmap_item); } @@ -419,6 +431,7 @@ static void remove_rmap_item_from_tree(struct rmap_item *rmap_item) BUG_ON(age > 2); if (!age) rb_erase(&rmap_item->node, &root_unstable_tree); + ksm_pages_unshared--; } rmap_item->address &= PAGE_MASK; @@ -995,6 +1008,7 @@ static struct rmap_item *unstable_tree_search_insert(struct page *page, rb_link_node(&rmap_item->node, parent, new); rb_insert_color(&rmap_item->node, &root_unstable_tree); + ksm_pages_unshared++; return NULL; } @@ -1091,6 +1105,8 @@ static void cmp_and_merge_page(struct page *page, struct rmap_item *rmap_item) if (!err) { rb_erase(&tree_rmap_item->node, &root_unstable_tree); tree_rmap_item->address &= ~NODE_FLAG; + ksm_pages_unshared--; + /* * If we fail to insert the page into the stable tree, * we will have 2 virtual addresses that are pointing @@ -1474,6 +1490,37 @@ static ssize_t pages_sharing_show(struct kobject *kobj, } KSM_ATTR_RO(pages_sharing); +static ssize_t pages_unshared_show(struct kobject *kobj, + struct kobj_attribute *attr, char *buf) +{ + return sprintf(buf, "%lu\n", ksm_pages_unshared); +} +KSM_ATTR_RO(pages_unshared); + +static ssize_t pages_volatile_show(struct kobject *kobj, + struct kobj_attribute *attr, char *buf) +{ + long ksm_pages_volatile; + + ksm_pages_volatile = ksm_rmap_items - ksm_pages_shared + - ksm_pages_sharing - ksm_pages_unshared; + /* + * It was not worth any locking to calculate that statistic, + * but it might therefore sometimes be negative: conceal that. + */ + if (ksm_pages_volatile < 0) + ksm_pages_volatile = 0; + return sprintf(buf, "%ld\n", ksm_pages_volatile); +} +KSM_ATTR_RO(pages_volatile); + +static ssize_t full_scans_show(struct kobject *kobj, + struct kobj_attribute *attr, char *buf) +{ + return sprintf(buf, "%lu\n", ksm_scan.seqnr); +} +KSM_ATTR_RO(full_scans); + static struct attribute *ksm_attrs[] = { &sleep_millisecs_attr.attr, &pages_to_scan_attr.attr, @@ -1481,6 +1528,9 @@ static struct attribute *ksm_attrs[] = { &max_kernel_pages_attr.attr, &pages_shared_attr.attr, &pages_sharing_attr.attr, + &pages_unshared_attr.attr, + &pages_volatile_attr.attr, + &full_scans_attr.attr, NULL, }; |