[PATCH kselftest-next 2/2] kselftests: memcg: speed up the memory.high test

From: Roman Gushchin
Date: Mon Dec 02 2019 - 18:42:21 EST


After commit 0e4b01df8659 ("mm, memcg: throttle allocators when
failing reclaim over memory.high") allocating memory over memory.high
became very time consuming. But it's exactly what the memory.high
test from cgroup kselftests is doing: it tries to allocate 100M with
30M memory.high value. It takes forever to complete.

In order to keep it passing (or failing) in a reasonable amount of
time let's try to allocate only a little over 30M: 31M to be precise.

With this change test_memcontrol finishes in a reasonable amount of
time:
$ time ./test_memcontrol
ok 1 test_memcg_subtree_control
ok 2 test_memcg_current
ok 3 test_memcg_min
ok 4 test_memcg_low
ok 5 test_memcg_high
ok 6 test_memcg_max
ok 7 test_memcg_oom_events
ok 8 test_memcg_swap_max
ok 9 test_memcg_sock
ok 10 test_memcg_oom_group_leaf_events
ok 11 test_memcg_oom_group_parent_events
ok 12 test_memcg_oom_group_score_events

real 0m2.273s
user 0m0.064s
sys 0m0.739s

Signed-off-by: Roman Gushchin <guro@xxxxxx>
Cc: Chris Down <chris@xxxxxxxxxxxxxx>
Cc: Johannes Weiner <hannes@xxxxxxxxxxx>
---
tools/testing/selftests/cgroup/test_memcontrol.c | 2 +-
1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/tools/testing/selftests/cgroup/test_memcontrol.c b/tools/testing/selftests/cgroup/test_memcontrol.c
index 60bfe53c0289..739fa90448f6 100644
--- a/tools/testing/selftests/cgroup/test_memcontrol.c
+++ b/tools/testing/selftests/cgroup/test_memcontrol.c
@@ -606,7 +606,7 @@ static int test_memcg_high(const char *root)
if (cg_write(memcg, "memory.high", "30M"))
goto cleanup;

- if (cg_run(memcg, alloc_anon, (void *)MB(100)))
+ if (cg_run(memcg, alloc_anon, (void *)MB(31)))
goto cleanup;

if (!cg_run(memcg, alloc_pagecache_50M_check, NULL))
--
2.17.1