From d0f209f68f80f9a152799760c230019e7f270b2a Mon Sep 17 00:00:00 2001 From: Hugh Dickins Date: Mon, 14 Dec 2009 17:59:34 -0800 Subject: ksm: remove unswappable max_kernel_pages Now that ksm pages are swappable, and the known holes plugged, remove mention of unswappable kernel pages from KSM documentation and comments. Remove the totalram_pages/4 initialization of max_kernel_pages. In fact, remove max_kernel_pages altogether - we can reinstate it if removal turns out to break someone's script; but if we later want to limit KSM's memory usage, limiting the stable nodes would not be an effective approach. Signed-off-by: Hugh Dickins Cc: Izik Eidus Cc: Andrea Arcangeli Cc: Chris Wright Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds --- mm/Kconfig | 2 +- mm/ksm.c | 41 ++--------------------------------------- 2 files changed, 3 insertions(+), 40 deletions(-) (limited to 'mm') diff --git a/mm/Kconfig b/mm/Kconfig index d4b5fff6ea0..2310984591e 100644 --- a/mm/Kconfig +++ b/mm/Kconfig @@ -212,7 +212,7 @@ config KSM Enable Kernel Samepage Merging: KSM periodically scans those areas of an application's address space that an app has advised may be mergeable. When it finds pages of identical content, it replaces - the many instances by a single resident page with that content, so + the many instances by a single page with that content, so saving memory until one or another app needs to modify the content. Recommended for use with KVM, or with other duplicative applications. See Documentation/vm/ksm.txt for more information: KSM is inactive diff --git a/mm/ksm.c b/mm/ksm.c index d4c228a9d27..56a0da1f997 100644 --- a/mm/ksm.c +++ b/mm/ksm.c @@ -179,9 +179,6 @@ 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; - /* Number of pages ksmd should scan in one batch */ static unsigned int ksm_thread_pages_to_scan = 100; @@ -943,14 +940,6 @@ static struct page *try_to_merge_two_pages(struct rmap_item *rmap_item, { int err; - /* - * The number of nodes in the stable tree - * is the number of kernel pages that we hold. - */ - if (ksm_max_kernel_pages && - ksm_max_kernel_pages <= ksm_pages_shared) - return NULL; - err = try_to_merge_with_ksm_page(rmap_item, page, NULL); if (!err) { err = try_to_merge_with_ksm_page(tree_rmap_item, @@ -1850,8 +1839,8 @@ static ssize_t run_store(struct kobject *kobj, struct kobj_attribute *attr, /* * KSM_RUN_MERGE sets ksmd running, and 0 stops it running. * KSM_RUN_UNMERGE stops it running and unmerges all rmap_items, - * breaking COW to free the unswappable pages_shared (but leaves - * mm_slots on the list for when ksmd may be set running again). + * breaking COW to free the pages_shared (but leaves mm_slots + * on the list for when ksmd may be set running again). */ mutex_lock(&ksm_thread_mutex); @@ -1876,29 +1865,6 @@ static ssize_t run_store(struct kobject *kobj, struct kobj_attribute *attr, } KSM_ATTR(run); -static ssize_t max_kernel_pages_store(struct kobject *kobj, - struct kobj_attribute *attr, - const char *buf, size_t count) -{ - int err; - unsigned long nr_pages; - - err = strict_strtoul(buf, 10, &nr_pages); - if (err) - return -EINVAL; - - ksm_max_kernel_pages = nr_pages; - - return count; -} - -static ssize_t max_kernel_pages_show(struct kobject *kobj, - struct kobj_attribute *attr, char *buf) -{ - return sprintf(buf, "%lu\n", ksm_max_kernel_pages); -} -KSM_ATTR(max_kernel_pages); - static ssize_t pages_shared_show(struct kobject *kobj, struct kobj_attribute *attr, char *buf) { @@ -1948,7 +1914,6 @@ static struct attribute *ksm_attrs[] = { &sleep_millisecs_attr.attr, &pages_to_scan_attr.attr, &run_attr.attr, - &max_kernel_pages_attr.attr, &pages_shared_attr.attr, &pages_sharing_attr.attr, &pages_unshared_attr.attr, @@ -1968,8 +1933,6 @@ static int __init ksm_init(void) struct task_struct *ksm_thread; int err; - ksm_max_kernel_pages = totalram_pages / 4; - err = ksm_slab_init(); if (err) goto out; -- cgit v1.2.3