mem_cgroup_reclaimable() checks whether a cgroup has reclaimable pages
on *any* NUMA node. However, the only place where it's called is
mem_cgroup_soft_reclaim(), which tries to reclaim memory from a
*specific* zone. So the way how it's used is incorrect - it will return
true even if the cgroup doesn't have pages on the zone we're scanning.
I think we can get rid of this check completely, because
mem_cgroup_shrink_node_zone(), which is called by
mem_cgroup_soft_reclaim() if mem_cgroup_reclaimable() returns true, is
equivalent to shrink_lruvec(), which exits almost immediately if the
lruvec passed to it is empty. So there's no need to optimize anything
here. Besides, we don't have such a check in the general scan path
(shrink_zone) either.
Signed-off-by: Vladimir Davydov <vdavydov@xxxxxxxxxxxxx>
---
mm/memcontrol.c | 43 -------------------------------------------
1 file changed, 43 deletions(-)
diff --git a/mm/memcontrol.c b/mm/memcontrol.c
index 53393e27ff03..833b6a696aab 100644
--- a/mm/memcontrol.c
+++ b/mm/memcontrol.c
@@ -1799,52 +1799,11 @@ int mem_cgroup_select_victim_node(struct mem_cgroup *memcg)
memcg->last_scanned_node = node;
return node;
}
-
-/*
- * Check all nodes whether it contains reclaimable pages or not.
- * For quick scan, we make use of scan_nodes. This will allow us to skip
- * unused nodes. But scan_nodes is lazily updated and may not cotain
- * enough new information. We need to do double check.
- */
-static bool mem_cgroup_reclaimable(struct mem_cgroup *memcg, bool noswap)
-{
- int nid;
-
- /*
- * quick check...making use of scan_node.
- * We can skip unused nodes.
- */
- if (!nodes_empty(memcg->scan_nodes)) {
- for (nid = first_node(memcg->scan_nodes);
- nid < MAX_NUMNODES;
- nid = next_node(nid, memcg->scan_nodes)) {
-
- if (test_mem_cgroup_node_reclaimable(memcg, nid, noswap))
- return true;
- }
- }
- /*
- * Check rest of nodes.
- */
- for_each_node_state(nid, N_MEMORY) {
- if (node_isset(nid, memcg->scan_nodes))
- continue;
- if (test_mem_cgroup_node_reclaimable(memcg, nid, noswap))
- return true;
- }
- return false;
-}
-
#else
int mem_cgroup_select_victim_node(struct mem_cgroup *memcg)
{
return 0;
}
-
-static bool mem_cgroup_reclaimable(struct mem_cgroup *memcg, bool noswap)
-{
- return test_mem_cgroup_node_reclaimable(memcg, 0, noswap);
-}
#endif
static int mem_cgroup_soft_reclaim(struct mem_cgroup *root_memcg,
@@ -1888,8 +1847,6 @@ static int mem_cgroup_soft_reclaim(struct mem_cgroup *root_memcg,
}
continue;
}
- if (!mem_cgroup_reclaimable(victim, false))
- continue;
total += mem_cgroup_shrink_node_zone(victim, gfp_mask, false,
zone, &nr_scanned);
*total_scanned += nr_scanned;
--
1.7.10.4
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