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From:   Roman Gushchin <roman.gushchin@linux.dev>
To:     Andrew Morton <akpm@linux-foundation.org>
Cc:     Tejun Heo <tj@kernel.org>, David Vernet <void@manifault.com>,
        linux-kernel@vger.kernel.org, linux-mm@kvack.org,
        cgroups@vger.kernel.org, Johannes Weiner <hannes@cmpxchg.org>,
        Michal Hocko <mhocko@kernel.org>,
        Shakeel Butt <shakeelb@google.com>,
        Roman Gushchin <roman.gushchin@linux.dev>,
        Chris Down <chris@chrisdown.name>
Subject: [PATCH 2/4] kselftests: memcg: speed up the memory.high test
Date:   Thu, 14 Apr 2022 17:01:31 -0700
Message-Id: <20220415000133.3955987-3-roman.gushchin@linux.dev>
In-Reply-To: <20220415000133.3955987-1-roman.gushchin@linux.dev>
References: <20220415000133.3955987-1-roman.gushchin@linux.dev>
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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 <roman.gushchin@linux.dev>
Cc: Chris Down <chris@chrisdown.name>
Cc: Johannes Weiner <hannes@cmpxchg.org>
---
 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 00b430e7f2a2..9c1f19fe2e37 100644
--- a/tools/testing/selftests/cgroup/test_memcontrol.c
+++ b/tools/testing/selftests/cgroup/test_memcontrol.c
@@ -607,7 +607,7 @@ 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))
-- 
2.35.1