From: Wei Yang <richard.weiyang@gmail.com>
To: hannes@cmpxchg.org, mhocko@kernel.org, vdavydov.dev@gmail.com,
akpm@linux-foundation.org
Cc: cgroups@vger.kernel.org, linux-mm@kvack.org,
Wei Yang <richard.weiyang@gmail.com>
Subject: [Patch v2 3/3] mm/memcg: move generation assignment and comparison together
Date: Wed, 30 Mar 2022 23:47:19 +0000 [thread overview]
Message-ID: <20220330234719.18340-4-richard.weiyang@gmail.com> (raw)
In-Reply-To: <20220330234719.18340-1-richard.weiyang@gmail.com>
For each round-trip, we assign generation on first invocation and
compare it on subsequent invocations.
Let's move them together to make it more self-explaining. Also this
reduce a check on prev.
[hannes@cmpxchg.org: better comment to explain reclaim model]
Signed-off-by: Wei Yang <richard.weiyang@gmail.com>
Acked-by: Johannes Weiner <hannes@cmpxchg.org>
---
v2: a better comment from Johannes
---
mm/memcontrol.c | 10 +++++++---
1 file changed, 7 insertions(+), 3 deletions(-)
diff --git a/mm/memcontrol.c b/mm/memcontrol.c
index 5d433b79ba47..2cd8bfdec379 100644
--- a/mm/memcontrol.c
+++ b/mm/memcontrol.c
@@ -1013,7 +1013,13 @@ struct mem_cgroup *mem_cgroup_iter(struct mem_cgroup *root,
mz = root->nodeinfo[reclaim->pgdat->node_id];
iter = &mz->iter;
- if (prev && reclaim->generation != iter->generation)
+ /*
+ * On start, join the current reclaim iteration cycle.
+ * Exit when a concurrent walker completes it.
+ */
+ if (!prev)
+ reclaim->generation = iter->generation;
+ else if (reclaim->generation != iter->generation)
goto out_unlock;
while (1) {
@@ -1075,8 +1081,6 @@ struct mem_cgroup *mem_cgroup_iter(struct mem_cgroup *root,
if (!memcg)
iter->generation++;
- else if (!prev)
- reclaim->generation = iter->generation;
}
out_unlock:
--
2.33.1
next prev parent reply other threads:[~2022-03-30 23:47 UTC|newest]
Thread overview: 8+ messages / expand[flat|nested] mbox.gz Atom feed top
2022-03-30 23:47 [Patch v2 0/3] mm/memcg: some cleanup for mem_cgroup_iter() Wei Yang
2022-03-30 23:47 ` [Patch v2 1/3] mm/memcg: set memcg after css verified and got reference Wei Yang
2022-03-31 0:20 ` Roman Gushchin
2022-03-30 23:47 ` [Patch v2 2/3] mm/memcg: set pos explicitly for reclaim and !reclaim Wei Yang
2022-03-31 0:21 ` Roman Gushchin
2022-03-31 15:03 ` Johannes Weiner
2022-03-30 23:47 ` Wei Yang [this message]
2022-03-31 0:28 ` [Patch v2 3/3] mm/memcg: move generation assignment and comparison together Roman Gushchin
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