diff mbox series

[v5,2/7] mm: memcontrol: convert NR_ANON_THPS account to pages

Message ID 20201217034356.4708-3-songmuchun@bytedance.com (mailing list archive)
State New, archived
Headers show
Series Convert all THP vmstat counters to pages | expand

Commit Message

Muchun Song Dec. 17, 2020, 3:43 a.m. UTC
Currently we use struct per_cpu_nodestat to cache the vmstat
counters, which leads to inaccurate statistics expecially THP
vmstat counters. In the systems with hundreads 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_ANON_THPS 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.

Signed-off-by: Muchun Song <songmuchun@bytedance.com>
---
 drivers/base/node.c    | 15 +++++++++------
 fs/proc/meminfo.c      |  2 +-
 include/linux/mmzone.h | 10 ++++++++++
 mm/huge_memory.c       |  3 ++-
 mm/memcontrol.c        | 20 ++++++--------------
 mm/page_alloc.c        |  2 +-
 mm/rmap.c              |  6 +++---
 mm/vmstat.c            | 11 +++++++++--
 8 files changed, 41 insertions(+), 28 deletions(-)

Comments

Shakeel Butt Dec. 23, 2020, 10:08 p.m. UTC | #1
On Wed, Dec 16, 2020 at 7:45 PM Muchun Song <songmuchun@bytedance.com> wrote:
>
> Currently we use struct per_cpu_nodestat to cache the vmstat
> counters, which leads to inaccurate statistics expecially THP

*especially

> vmstat counters. In the systems with hundreads of processors

*hundreds

> 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_ANON_THPS 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.
>
> Signed-off-by: Muchun Song <songmuchun@bytedance.com>

I agree with the motivation behind this patch but I would like to see
some performance numbers in the commit message. We might agree to pay
the price but at least we will know what exactly that cost is.
Muchun Song Dec. 24, 2020, 2:45 a.m. UTC | #2
On Thu, Dec 24, 2020 at 6:08 AM Shakeel Butt <shakeelb@google.com> wrote:
>
> On Wed, Dec 16, 2020 at 7:45 PM Muchun Song <songmuchun@bytedance.com> wrote:
> >
> > Currently we use struct per_cpu_nodestat to cache the vmstat
> > counters, which leads to inaccurate statistics expecially THP
>
> *especially

Thanks.

>
> > vmstat counters. In the systems with hundreads of processors
>
> *hundreds

Thanks.

>
> > 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_ANON_THPS 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.
> >
> > Signed-off-by: Muchun Song <songmuchun@bytedance.com>
>
> I agree with the motivation behind this patch but I would like to see
> some performance numbers in the commit message. We might agree to pay
> the price but at least we will know what exactly that cost is.

Do you have any recommendations about benchmarks?
I can do a test. Thanks very much.
diff mbox series

Patch

diff --git a/drivers/base/node.c b/drivers/base/node.c
index 04f71c7bc3f8..6da0c3508bc9 100644
--- a/drivers/base/node.c
+++ b/drivers/base/node.c
@@ -461,8 +461,7 @@  static ssize_t node_read_meminfo(struct device *dev,
 			     nid, K(sunreclaimable)
 #ifdef CONFIG_TRANSPARENT_HUGEPAGE
 			     ,
-			     nid, K(node_page_state(pgdat, NR_ANON_THPS) *
-				    HPAGE_PMD_NR),
+			     nid, K(node_page_state(pgdat, NR_ANON_THPS)),
 			     nid, K(node_page_state(pgdat, NR_SHMEM_THPS) *
 				    HPAGE_PMD_NR),
 			     nid, K(node_page_state(pgdat, NR_SHMEM_PMDMAPPED) *
@@ -519,10 +518,14 @@  static ssize_t node_read_vmstat(struct device *dev,
 				     sum_zone_numa_state(nid, i));
 
 #endif
-	for (i = 0; i < NR_VM_NODE_STAT_ITEMS; i++)
-		len += sysfs_emit_at(buf, len, "%s %lu\n",
-				     node_stat_name(i),
-				     node_page_state_pages(pgdat, i));
+	for (i = 0; i < NR_VM_NODE_STAT_ITEMS; i++) {
+		unsigned long pages = node_page_state_pages(pgdat, i);
+
+		if (vmstat_item_print_in_thp(i))
+			pages /= HPAGE_PMD_NR;
+		len += sysfs_emit_at(buf, len, "%s %lu\n", node_stat_name(i),
+				     pages);
+	}
 
 	return len;
 }
diff --git a/fs/proc/meminfo.c b/fs/proc/meminfo.c
index d6fc74619625..a635c8a84ddf 100644
--- a/fs/proc/meminfo.c
+++ b/fs/proc/meminfo.c
@@ -129,7 +129,7 @@  static int meminfo_proc_show(struct seq_file *m, void *v)
 
 #ifdef CONFIG_TRANSPARENT_HUGEPAGE
 	show_val_kb(m, "AnonHugePages:  ",
-		    global_node_page_state(NR_ANON_THPS) * HPAGE_PMD_NR);
+		    global_node_page_state(NR_ANON_THPS));
 	show_val_kb(m, "ShmemHugePages: ",
 		    global_node_page_state(NR_SHMEM_THPS) * HPAGE_PMD_NR);
 	show_val_kb(m, "ShmemPmdMapped: ",
diff --git a/include/linux/mmzone.h b/include/linux/mmzone.h
index b593316bff3d..71029c09782b 100644
--- a/include/linux/mmzone.h
+++ b/include/linux/mmzone.h
@@ -210,6 +210,16 @@  enum node_stat_item {
 };
 
 /*
+ * Returns true if the item should be printed in THPs (/proc/vmstat
+ * currently prints number of anon, file and shmem THPs. But the item
+ * is charged in pages).
+ */
+static __always_inline bool vmstat_item_print_in_thp(enum node_stat_item item)
+{
+	return item == NR_ANON_THPS;
+}
+
+/*
  * Returns true if the value is measured in bytes (most vmstat values are
  * measured in pages). This defines the API part, the internal representation
  * might be different.
diff --git a/mm/huge_memory.c b/mm/huge_memory.c
index 10dd3cae5f53..66ec454120de 100644
--- a/mm/huge_memory.c
+++ b/mm/huge_memory.c
@@ -2178,7 +2178,8 @@  static void __split_huge_pmd_locked(struct vm_area_struct *vma, pmd_t *pmd,
 		lock_page_memcg(page);
 		if (atomic_add_negative(-1, compound_mapcount_ptr(page))) {
 			/* Last compound_mapcount is gone. */
-			__dec_lruvec_page_state(page, NR_ANON_THPS);
+			__mod_lruvec_page_state(page, NR_ANON_THPS,
+						-HPAGE_PMD_NR);
 			if (TestClearPageDoubleMap(page)) {
 				/* No need in mapcount reference anymore */
 				for (i = 0; i < HPAGE_PMD_NR; i++)
diff --git a/mm/memcontrol.c b/mm/memcontrol.c
index 8818bf64d6fe..b18e25a5cdf3 100644
--- a/mm/memcontrol.c
+++ b/mm/memcontrol.c
@@ -1532,7 +1532,7 @@  static struct memory_stat memory_stats[] = {
 	 * on some architectures, the macro of HPAGE_PMD_SIZE is not
 	 * constant(e.g. powerpc).
 	 */
-	{ "anon_thp", 0, NR_ANON_THPS },
+	{ "anon_thp", PAGE_SIZE, NR_ANON_THPS },
 	{ "file_thp", 0, NR_FILE_THPS },
 	{ "shmem_thp", 0, NR_SHMEM_THPS },
 #endif
@@ -1565,8 +1565,7 @@  static int __init memory_stats_init(void)
 
 	for (i = 0; i < ARRAY_SIZE(memory_stats); i++) {
 #ifdef CONFIG_TRANSPARENT_HUGEPAGE
-		if (memory_stats[i].idx == NR_ANON_THPS ||
-		    memory_stats[i].idx == NR_FILE_THPS ||
+		if (memory_stats[i].idx == NR_FILE_THPS ||
 		    memory_stats[i].idx == NR_SHMEM_THPS)
 			memory_stats[i].ratio = HPAGE_PMD_SIZE;
 #endif
@@ -4088,10 +4087,6 @@  static int memcg_stat_show(struct seq_file *m, void *v)
 		if (memcg1_stats[i] == MEMCG_SWAP && !do_memsw_account())
 			continue;
 		nr = memcg_page_state_local(memcg, memcg1_stats[i]);
-#ifdef CONFIG_TRANSPARENT_HUGEPAGE
-		if (memcg1_stats[i] == NR_ANON_THPS)
-			nr *= HPAGE_PMD_NR;
-#endif
 		seq_printf(m, "%s %lu\n", memcg1_stat_names[i], nr * PAGE_SIZE);
 	}
 
@@ -4122,10 +4117,6 @@  static int memcg_stat_show(struct seq_file *m, void *v)
 		if (memcg1_stats[i] == MEMCG_SWAP && !do_memsw_account())
 			continue;
 		nr = memcg_page_state(memcg, memcg1_stats[i]);
-#ifdef CONFIG_TRANSPARENT_HUGEPAGE
-		if (memcg1_stats[i] == NR_ANON_THPS)
-			nr *= HPAGE_PMD_NR;
-#endif
 		seq_printf(m, "total_%s %llu\n", memcg1_stat_names[i],
 						(u64)nr * PAGE_SIZE);
 	}
@@ -5653,10 +5644,11 @@  static int mem_cgroup_move_account(struct page *page,
 			__mod_lruvec_state(from_vec, NR_ANON_MAPPED, -nr_pages);
 			__mod_lruvec_state(to_vec, NR_ANON_MAPPED, nr_pages);
 			if (PageTransHuge(page)) {
-				__dec_lruvec_state(from_vec, NR_ANON_THPS);
-				__inc_lruvec_state(to_vec, NR_ANON_THPS);
+				__mod_lruvec_state(from_vec, NR_ANON_THPS,
+						   -nr_pages);
+				__mod_lruvec_state(to_vec, NR_ANON_THPS,
+						   nr_pages);
 			}
-
 		}
 	} else {
 		__mod_lruvec_state(from_vec, NR_FILE_PAGES, -nr_pages);
diff --git a/mm/page_alloc.c b/mm/page_alloc.c
index 469e28f95ce7..1700f52b7869 100644
--- a/mm/page_alloc.c
+++ b/mm/page_alloc.c
@@ -5580,7 +5580,7 @@  void show_free_areas(unsigned int filter, nodemask_t *nodemask)
 			K(node_page_state(pgdat, NR_SHMEM_THPS) * HPAGE_PMD_NR),
 			K(node_page_state(pgdat, NR_SHMEM_PMDMAPPED)
 					* HPAGE_PMD_NR),
-			K(node_page_state(pgdat, NR_ANON_THPS) * HPAGE_PMD_NR),
+			K(node_page_state(pgdat, NR_ANON_THPS)),
 #endif
 			K(node_page_state(pgdat, NR_WRITEBACK_TEMP)),
 			node_page_state(pgdat, NR_KERNEL_STACK_KB),
diff --git a/mm/rmap.c b/mm/rmap.c
index 08c56aaf72eb..c4d5c63cfd29 100644
--- a/mm/rmap.c
+++ b/mm/rmap.c
@@ -1144,7 +1144,7 @@  void do_page_add_anon_rmap(struct page *page,
 		 * disabled.
 		 */
 		if (compound)
-			__inc_lruvec_page_state(page, NR_ANON_THPS);
+			__mod_lruvec_page_state(page, NR_ANON_THPS, nr);
 		__mod_lruvec_page_state(page, NR_ANON_MAPPED, nr);
 	}
 
@@ -1186,7 +1186,7 @@  void page_add_new_anon_rmap(struct page *page,
 		if (hpage_pincount_available(page))
 			atomic_set(compound_pincount_ptr(page), 0);
 
-		__inc_lruvec_page_state(page, NR_ANON_THPS);
+		__mod_lruvec_page_state(page, NR_ANON_THPS, nr);
 	} else {
 		/* Anon THP always mapped first with PMD */
 		VM_BUG_ON_PAGE(PageTransCompound(page), page);
@@ -1292,7 +1292,7 @@  static void page_remove_anon_compound_rmap(struct page *page)
 	if (!IS_ENABLED(CONFIG_TRANSPARENT_HUGEPAGE))
 		return;
 
-	__dec_lruvec_page_state(page, NR_ANON_THPS);
+	__mod_lruvec_page_state(page, NR_ANON_THPS, -thp_nr_pages(page));
 
 	if (TestClearPageDoubleMap(page)) {
 		/*
diff --git a/mm/vmstat.c b/mm/vmstat.c
index 663f49ed1fd6..37c9e7b21e1e 100644
--- a/mm/vmstat.c
+++ b/mm/vmstat.c
@@ -1624,8 +1624,12 @@  static void zoneinfo_show_print(struct seq_file *m, pg_data_t *pgdat,
 	if (is_zone_first_populated(pgdat, zone)) {
 		seq_printf(m, "\n  per-node stats");
 		for (i = 0; i < NR_VM_NODE_STAT_ITEMS; i++) {
+			unsigned long pages = node_page_state_pages(pgdat, i);
+
+			if (vmstat_item_print_in_thp(i))
+				pages /= HPAGE_PMD_NR;
 			seq_printf(m, "\n      %-12s %lu", node_stat_name(i),
-				   node_page_state_pages(pgdat, i));
+				   pages);
 		}
 	}
 	seq_printf(m,
@@ -1745,8 +1749,11 @@  static void *vmstat_start(struct seq_file *m, loff_t *pos)
 	v += NR_VM_NUMA_STAT_ITEMS;
 #endif
 
-	for (i = 0; i < NR_VM_NODE_STAT_ITEMS; i++)
+	for (i = 0; i < NR_VM_NODE_STAT_ITEMS; i++) {
 		v[i] = global_node_page_state_pages(i);
+		if (vmstat_item_print_in_thp(i))
+			v[i] /= HPAGE_PMD_NR;
+	}
 	v += NR_VM_NODE_STAT_ITEMS;
 
 	global_dirty_limits(v + NR_DIRTY_BG_THRESHOLD,