linux-kernel - [PATCH] mm: bump PGSTEAL*/PGSCAN*/ALLOCSTALL counters in memcg reclaim

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Date:   Mon, 29 May 2017 14:01:41 +0100
From:   Roman Gushchin <guro@...com>
To:     Balbir Singh <bsingharora@...il.com>
CC:     Roman Gushchin <guro@...com>, Michal Hocko <mhocko@...e.com>,
        Johannes Weiner <hannes@...xchg.org>,
        Vladimir Davydov <vdavydov.dev@...il.com>,
        <kernel-team@...com>, <linux-mm@...ck.org>,
        <linux-kernel@...r.kernel.org>
Subject: [PATCH] mm: bump PGSTEAL*/PGSCAN*/ALLOCSTALL counters in memcg reclaim

Historically, PGSTEAL*/PGSCAN*/ALLOCSTALL counters were used to
account only for global reclaim events, memory cgroup targeted reclaim
was ignored.

It doesn't make sense anymore, because the whole reclaim path
is designed around cgroups. Also, per-cgroup counters can exceed the
corresponding global counters, what can be confusing.

So, make PGSTEAL*/PGSCAN*/ALLOCSTALL counters reflect sum of any
reclaim activity in the system.

Signed-off-by: Roman Gushchin <guro@...com>
Cc: Balbir Singh <bsingharora@...il.com>
Cc: Michal Hocko <mhocko@...e.com>
Cc: Johannes Weiner <hannes@...xchg.org>
Cc: Vladimir Davydov <vdavydov.dev@...il.com>
Cc: kernel-team@...com
Cc: linux-mm@...ck.org
Cc: linux-kernel@...r.kernel.org
---
 mm/vmscan.c | 15 +++++----------
 1 file changed, 5 insertions(+), 10 deletions(-)

diff --git a/mm/vmscan.c b/mm/vmscan.c
index 7c2a36b..77253b1 100644
--- a/mm/vmscan.c
+++ b/mm/vmscan.c
@@ -1765,13 +1765,11 @@ shrink_inactive_list(unsigned long nr_to_scan, struct lruvec *lruvec,
 	reclaim_stat->recent_scanned[file] += nr_taken;
 
 	if (current_is_kswapd()) {
-		if (global_reclaim(sc))
-			__count_vm_events(PGSCAN_KSWAPD, nr_scanned);
+		__count_vm_events(PGSCAN_KSWAPD, nr_scanned);
 		count_memcg_events(lruvec_memcg(lruvec), PGSCAN_KSWAPD,
 				   nr_scanned);
 	} else {
-		if (global_reclaim(sc))
-			__count_vm_events(PGSCAN_DIRECT, nr_scanned);
+		__count_vm_events(PGSCAN_DIRECT, nr_scanned);
 		count_memcg_events(lruvec_memcg(lruvec), PGSCAN_DIRECT,
 				   nr_scanned);
 	}
@@ -1786,13 +1784,11 @@ shrink_inactive_list(unsigned long nr_to_scan, struct lruvec *lruvec,
 	spin_lock_irq(&pgdat->lru_lock);
 
 	if (current_is_kswapd()) {
-		if (global_reclaim(sc))
-			__count_vm_events(PGSTEAL_KSWAPD, nr_reclaimed);
+		__count_vm_events(PGSTEAL_KSWAPD, nr_reclaimed);
 		count_memcg_events(lruvec_memcg(lruvec), PGSTEAL_KSWAPD,
 				   nr_reclaimed);
 	} else {
-		if (global_reclaim(sc))
-			__count_vm_events(PGSTEAL_DIRECT, nr_reclaimed);
+		__count_vm_events(PGSTEAL_DIRECT, nr_reclaimed);
 		count_memcg_events(lruvec_memcg(lruvec), PGSTEAL_DIRECT,
 				   nr_reclaimed);
 	}
@@ -2828,8 +2824,7 @@ static unsigned long do_try_to_free_pages(struct zonelist *zonelist,
 retry:
 	delayacct_freepages_start();
 
-	if (global_reclaim(sc))
-		__count_zid_vm_events(ALLOCSTALL, sc->reclaim_idx, 1);
+	__count_zid_vm_events(ALLOCSTALL, sc->reclaim_idx, 1);
 
 	do {
 		vmpressure_prio(sc->gfp_mask, sc->target_mem_cgroup,
-- 
2.7.4