[LTP] [PATCH] memcg_function_test: do a warmup before actual test

[Jan S. <jst...@re...>]

This test relies on getting correct rss number out of memory.stat.
Very rarely it fails and finds bigger number than expected,
for example:
memcg_function_test    6  TFAIL  :  rss=8192/4096

My assumption is that extra page is faulted in as result of
need for another stack page.

Documentation describes it as:
"rss - # of bytes of anonymous and swap cache memory."

This includes also stack pages. I intentionally modified
memcg_process' sigusr handler to grab few extra stack pages,
to confirm, that these indeed contribute to this number.

This patch adds a 'warmup' before actual test. The point
is to exercise the whole code path, so that any page fault,
which is unrelated to actual test occurs before process is
moved to target cgroup.

What happens now is:
spawn process
[NEW] signal it with SIGUSR1 (alloc)
[NEW] signal it with SIGUSR1 (free)
move it to cgroup
signal it with SIGUSR1 (alloc)
check rss in memory.stat
signal it with SIGUSR1 (free)
optionally check rss in memory.stat

Signed-off-by: Jan Stancek <jst...@re...>
---
  .../memcg/functional/memcg_function_test.sh        |   43 
++++++++++++++++++++
  1 files changed, 43 insertions(+), 0 deletions(-)