Currently, we get the vm_swappiness via vmscan_swappiness(), which
calls global_reclaim() to check if this is a global reclaim.
Besides, the current implementation of global_reclaim() always returns
true for the !CONFIG_MEGCG case, and judges the other case by checking
whether scan_control->target_mem_cgroup is null or not.
Thus, we could just use two versions of vmscan_swappiness() based on
MEMCG Kconfig , to eliminate the unnecessary run-time cost for
the !CONFIG_MEMCG at all, and to squash all memcg-related checking
into the CONFIG_MEMCG version.
Signed-off-by: Zhan Jianyu <nasa4836@xxxxxxxxx>
---
mm/memcontrol.c | 6 +++++-
mm/vmscan.c | 9 +++++++--
2 files changed, 12 insertions(+), 3 deletions(-)
diff --git a/mm/memcontrol.c b/mm/memcontrol.c
index c5792a5..1290320 100644
--- a/mm/memcontrol.c
+++ b/mm/memcontrol.c
@@ -1525,9 +1525,13 @@ static unsigned long mem_cgroup_margin(struct mem_cgroup *memcg)
int mem_cgroup_swappiness(struct mem_cgroup *memcg)
{
- struct cgroup *cgrp = memcg->css.cgroup;
+ struct cgroup *cgrp;
+
+ if (!memcg)
+ return vm_swappiness;
/* root ? */
+ cgrp = memcg->css.cgroup;
if (cgrp->parent == NULL)
return vm_swappiness;
diff --git a/mm/vmscan.c b/mm/vmscan.c
index 2cff0d4..1de652d 100644
--- a/mm/vmscan.c
+++ b/mm/vmscan.c
@@ -1742,12 +1742,17 @@ static unsigned long shrink_list(enum lru_list lru, unsigned long nr_to_scan,
return shrink_inactive_list(nr_to_scan, lruvec, sc, lru);
}
+#ifdef CONFIG_MEMCG
static int vmscan_swappiness(struct scan_control *sc)
{
- if (global_reclaim(sc))
- return vm_swappiness;
return mem_cgroup_swappiness(sc->target_mem_cgroup);
}
+#else
+static int vmscan_swappiness(struct scan_control *sc)
+{
+ return vm_swappiness;
+}
+#endif
enum scan_balance {
SCAN_EQUAL,
--
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