The patch titled
ksm: add vm_stat and meminfo entry to reflect pte mapping to ksm pages
has been added to the -mm tree. Its filename is
ksm-add-vm_stat-and-meminfo-entry-to-reflect-pte-mapping-to-ksm-pages.patch
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------------------------------------------------------
Subject: ksm: add vm_stat and meminfo entry to reflect pte mapping to ksm pages
From: Nai Xia <nai.xia@xxxxxxxxx>
ksm_pages_sharing is updated by ksmd periodically. In some cases, it
cannot reflect the actual savings and makes the benchmarks on volatile
VMAs very inaccurate.
This patch adds a vm_stat entry and lets the /proc/meminfo show
information about how much virutal address pte is being mapped to ksm
pages. With default ksm paramters (pages_to_scan==100 &&
sleep_millisecs==20), this can result in 50% more accurate averaged
savings result for the following test program. Bigger sleep_millisecs
values will increase this deviation.
/*
* This test program triggers frequent faults on merged ksm pages but
* still keeps the faulted pages mergeable.
*/
#include <stdio.h>
#include <stdlib.h>
#include <errno.h>
#include <string.h>
#include <unistd.h>
#include <sys/mman.h>
#define MADV_MERGEABLE 12
#define MADV_UNMERGEABLE 13
#define SIZE (1000*1024*1024)
#define SEED 1
#define PAGE_SIZE 4096
int main(int argc, char **argv)
{
char *p;
int j;
long feed = 1, new_feed, tmp;
unsigned int offset;
int status;
int ret;
pid_t child;
child = fork();
p = mmap(NULL, SIZE, PROT_WRITE|PROT_READ,
MAP_PRIVATE|MAP_ANONYMOUS, 0, 0);
if (p == MAP_FAILED) {
printf("mmap error\n");
return 0;
}
ret = madvise(p, SIZE, MADV_MERGEABLE);
if (ret==-1) {
printf("madvise failed \n");
return 0;
}
memset(p, feed, SIZE);
while (1) {
for (j=0; j<SIZE; j+= PAGE_SIZE) {
p[j] *= p[j]*1;
}
}
return 0;
}
Some of the patch lines removes trailing spaces in related files.
Signed-off-by: Nai Xia <nai.xia@xxxxxxxxx>
Cc: Izik Eidus <ieidus@xxxxxxxxxx>
Cc: Hugh Dickins <hugh.dickins@xxxxxxxxxxxxx>
Cc: Andrea Arcangeli <aarcange@xxxxxxxxxx>
Cc: Chris Wright <chrisw@xxxxxxxxxxxx>
Cc: Rik van Riel <riel@xxxxxxxxxx>
Signed-off-by: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx>
---
fs/proc/meminfo.c | 6 ++++++
include/linux/mmzone.h | 7 +++++--
mm/ksm.c | 5 +++++
mm/memory.c | 4 +++-
mm/rmap.c | 11 ++++++++---
5 files changed, 27 insertions(+), 6 deletions(-)
diff -puN fs/proc/meminfo.c~ksm-add-vm_stat-and-meminfo-entry-to-reflect-pte-mapping-to-ksm-pages fs/proc/meminfo.c
--- a/fs/proc/meminfo.c~ksm-add-vm_stat-and-meminfo-entry-to-reflect-pte-mapping-to-ksm-pages
+++ a/fs/proc/meminfo.c
@@ -87,6 +87,9 @@ static int meminfo_proc_show(struct seq_
"SUnreclaim: %8lu kB\n"
"KernelStack: %8lu kB\n"
"PageTables: %8lu kB\n"
+#ifdef CONFIG_KSM
+ "KsmSharing: %8lu kB\n"
+#endif
#ifdef CONFIG_QUICKLIST
"Quicklists: %8lu kB\n"
#endif
@@ -145,6 +148,9 @@ static int meminfo_proc_show(struct seq_
K(global_page_state(NR_SLAB_UNRECLAIMABLE)),
global_page_state(NR_KERNEL_STACK) * THREAD_SIZE / 1024,
K(global_page_state(NR_PAGETABLE)),
+#ifdef CONFIG_KSM
+ K(global_page_state(NR_KSM_PAGES_SHARING)),
+#endif
#ifdef CONFIG_QUICKLIST
K(quicklist_total_size()),
#endif
diff -puN include/linux/mmzone.h~ksm-add-vm_stat-and-meminfo-entry-to-reflect-pte-mapping-to-ksm-pages include/linux/mmzone.h
--- a/include/linux/mmzone.h~ksm-add-vm_stat-and-meminfo-entry-to-reflect-pte-mapping-to-ksm-pages
+++ a/include/linux/mmzone.h
@@ -115,6 +115,9 @@ enum zone_stat_item {
NUMA_OTHER, /* allocation from other node */
#endif
NR_ANON_TRANSPARENT_HUGEPAGES,
+#ifdef CONFIG_KSM
+ NR_KSM_PAGES_SHARING,
+#endif
NR_VM_ZONE_STAT_ITEMS };
/*
@@ -344,7 +347,7 @@ struct zone {
ZONE_PADDING(_pad1_)
/* Fields commonly accessed by the page reclaim scanner */
- spinlock_t lru_lock;
+ spinlock_t lru_lock;
struct zone_lru {
struct list_head list;
} lru[NR_LRU_LISTS];
@@ -722,7 +725,7 @@ static inline int is_normal_idx(enum zon
}
/**
- * is_highmem - helper function to quickly check if a struct zone is a
+ * is_highmem - helper function to quickly check if a struct zone is a
* highmem zone or not. This is an attempt to keep references
* to ZONE_{DMA/NORMAL/HIGHMEM/etc} in general code to a minimum.
* @zone - pointer to struct zone variable
diff -puN mm/ksm.c~ksm-add-vm_stat-and-meminfo-entry-to-reflect-pte-mapping-to-ksm-pages mm/ksm.c
--- a/mm/ksm.c~ksm-add-vm_stat-and-meminfo-entry-to-reflect-pte-mapping-to-ksm-pages
+++ a/mm/ksm.c
@@ -883,6 +883,7 @@ static int try_to_merge_one_page(struct
*/
if (write_protect_page(vma, page, &orig_pte) == 0) {
if (!kpage) {
+ long mapcount = page_mapcount(page);
/*
* While we hold page lock, upgrade page from
* PageAnon+anon_vma to PageKsm+NULL stable_node:
@@ -890,6 +891,10 @@ static int try_to_merge_one_page(struct
*/
set_page_stable_node(page, NULL);
mark_page_accessed(page);
+ if (mapcount)
+ add_zone_page_state(page_zone(page),
+ NR_KSM_PAGES_SHARING,
+ mapcount);
err = 0;
} else if (pages_identical(page, kpage))
err = replace_page(vma, page, kpage, orig_pte);
diff -puN mm/memory.c~ksm-add-vm_stat-and-meminfo-entry-to-reflect-pte-mapping-to-ksm-pages mm/memory.c
--- a/mm/memory.c~ksm-add-vm_stat-and-meminfo-entry-to-reflect-pte-mapping-to-ksm-pages
+++ a/mm/memory.c
@@ -719,6 +719,8 @@ copy_one_pte(struct mm_struct *dst_mm, s
rss[MM_ANONPAGES]++;
else
rss[MM_FILEPAGES]++;
+ if (PageKsm(page)) /* follows page_dup_rmap() */
+ inc_zone_page_state(page, NR_KSM_PAGES_SHARING);
}
out_set_pte:
@@ -1472,7 +1474,7 @@ int __get_user_pages(struct task_struct
VM_BUG_ON(!!pages != !!(gup_flags & FOLL_GET));
- /*
+ /*
* Require read or write permissions.
* If FOLL_FORCE is set, we only require the "MAY" flags.
*/
diff -puN mm/rmap.c~ksm-add-vm_stat-and-meminfo-entry-to-reflect-pte-mapping-to-ksm-pages mm/rmap.c
--- a/mm/rmap.c~ksm-add-vm_stat-and-meminfo-entry-to-reflect-pte-mapping-to-ksm-pages
+++ a/mm/rmap.c
@@ -805,9 +805,9 @@ void page_move_anon_rmap(struct page *pa
/**
* __page_set_anon_rmap - set up new anonymous rmap
- * @page: Page to add to rmap
+ * @page: Page to add to rmap
* @vma: VM area to add page to.
- * @address: User virtual address of the mapping
+ * @address: User virtual address of the mapping
* @exclusive: the page is exclusively owned by the current process
*/
static void __page_set_anon_rmap(struct page *page,
@@ -893,8 +893,10 @@ void do_page_add_anon_rmap(struct page *
__inc_zone_page_state(page,
NR_ANON_TRANSPARENT_HUGEPAGES);
}
- if (unlikely(PageKsm(page)))
+ if (unlikely(PageKsm(page))) {
+ __inc_zone_page_state(page, NR_KSM_PAGES_SHARING);
return;
+ }
VM_BUG_ON(!PageLocked(page));
VM_BUG_ON(address < vma->vm_start || address >= vma->vm_end);
@@ -953,6 +955,9 @@ void page_add_file_rmap(struct page *pag
*/
void page_remove_rmap(struct page *page)
{
+ if (PageKsm(page))
+ __dec_zone_page_state(page, NR_KSM_PAGES_SHARING);
+
/* page still mapped by someone else? */
if (!atomic_add_negative(-1, &page->_mapcount))
return;
_
Patches currently in -mm which might be from nai.xia@xxxxxxxxx are
ksm-add-vm_stat-and-meminfo-entry-to-reflect-pte-mapping-to-ksm-pages.patch
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