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authorMuchun Song <songmuchun@bytedance.com>2021-02-24 12:03:35 -0800
committerLinus Torvalds <torvalds@linux-foundation.org>2021-02-24 13:38:29 -0800
commita1528e21f8915e16252cda1137fe29672c918361 (patch)
tree7bdc3c3972c4416bcfcded7bc9c97714bc559dbb /mm/rmap.c
parent57b2847d3c1dc154923578efb47a12302a57d700 (diff)
downloadlinux-a1528e21f8915e16252cda1137fe29672c918361.tar.bz2
mm: memcontrol: convert NR_SHMEM_PMDMAPPED account to pages
Currently we use struct per_cpu_nodestat to cache the vmstat counters, which leads to inaccurate statistics especially THP vmstat counters. In the systems with hundreds of processors it can be GBs of memory. For example, for a 96 CPUs system, the threshold is the maximum number of 125. And the per cpu counters can cache 23.4375 GB in total. The THP page is already a form of batched addition (it will add 512 worth of memory in one go) so skipping the batching seems like sensible. Although every THP stats update overflows the per-cpu counter, resorting to atomic global updates. But it can make the statistics more accuracy for the THP vmstat counters. So we convert the NR_SHMEM_PMDMAPPED account to pages. This patch is consistent with 8f182270dfec ("mm/swap.c: flush lru pvecs on compound page arrival"). Doing this also can make the unit of vmstat counters more unified. Finally, the unit of the vmstat counters are pages, kB and bytes. The B/KB suffix can tell us that the unit is bytes or kB. The rest which is without suffix are pages. Link: https://lkml.kernel.org/r/20201228164110.2838-6-songmuchun@bytedance.com Signed-off-by: Muchun Song <songmuchun@bytedance.com> Cc: Alexey Dobriyan <adobriyan@gmail.com> Cc: Feng Tang <feng.tang@intel.com> Cc: Greg Kroah-Hartman <gregkh@linuxfoundation.org> Cc: Hugh Dickins <hughd@google.com> Cc: Johannes Weiner <hannes@cmpxchg.org> Cc: Joonsoo Kim <iamjoonsoo.kim@lge.com> Cc: Michal Hocko <mhocko@suse.com> Cc: NeilBrown <neilb@suse.de> Cc: Pankaj Gupta <pankaj.gupta@cloud.ionos.com> Cc: Rafael. J. Wysocki <rafael@kernel.org> Cc: Randy Dunlap <rdunlap@infradead.org> Cc: Roman Gushchin <guro@fb.com> Cc: Sami Tolvanen <samitolvanen@google.com> Cc: Shakeel Butt <shakeelb@google.com> Cc: Vladimir Davydov <vdavydov.dev@gmail.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Diffstat (limited to 'mm/rmap.c')
-rw-r--r--mm/rmap.c14
1 files changed, 10 insertions, 4 deletions
diff --git a/mm/rmap.c b/mm/rmap.c
index c4d5c63cfd29..1c1b576c0627 100644
--- a/mm/rmap.c
+++ b/mm/rmap.c
@@ -1211,14 +1211,17 @@ void page_add_file_rmap(struct page *page, bool compound)
VM_BUG_ON_PAGE(compound && !PageTransHuge(page), page);
lock_page_memcg(page);
if (compound && PageTransHuge(page)) {
- for (i = 0, nr = 0; i < thp_nr_pages(page); i++) {
+ int nr_pages = thp_nr_pages(page);
+
+ for (i = 0, nr = 0; i < nr_pages; i++) {
if (atomic_inc_and_test(&page[i]._mapcount))
nr++;
}
if (!atomic_inc_and_test(compound_mapcount_ptr(page)))
goto out;
if (PageSwapBacked(page))
- __inc_node_page_state(page, NR_SHMEM_PMDMAPPED);
+ __mod_lruvec_page_state(page, NR_SHMEM_PMDMAPPED,
+ nr_pages);
else
__inc_node_page_state(page, NR_FILE_PMDMAPPED);
} else {
@@ -1252,14 +1255,17 @@ static void page_remove_file_rmap(struct page *page, bool compound)
/* page still mapped by someone else? */
if (compound && PageTransHuge(page)) {
- for (i = 0, nr = 0; i < thp_nr_pages(page); i++) {
+ int nr_pages = thp_nr_pages(page);
+
+ for (i = 0, nr = 0; i < nr_pages; i++) {
if (atomic_add_negative(-1, &page[i]._mapcount))
nr++;
}
if (!atomic_add_negative(-1, compound_mapcount_ptr(page)))
return;
if (PageSwapBacked(page))
- __dec_node_page_state(page, NR_SHMEM_PMDMAPPED);
+ __mod_lruvec_page_state(page, NR_SHMEM_PMDMAPPED,
+ -nr_pages);
else
__dec_node_page_state(page, NR_FILE_PMDMAPPED);
} else {