[LTP] [RFC PATCH 4/4] memcg_stress_test.sh: allocate less than CommitLimit bytes

[Cyril Hrubis <chrubis@suse.cz>]

Hi!
> > I guess that when we decide to create the pressure inside of the memory
> > cgroup, instead of stressing the whole system, we may as well choose
> > small enough amount of memory, something as (RAM - 250Mb)/10 and be done
> > with it.
> 
> Yes, this should work as well.
> 
> I don't know how we could stress the whole system without the risk of 
> hitting an OOM. One idea which comes to my mind is about using a 
> top-level control group with a significant amount of memory assigned to 
> it (like mem_free / 2).
> 
> Could you, please, have a look at the attachment? I was playing with 
> this patch today and was able to stress my system without OOM.
> 
> However, this scheme may result in a very intensive swapping if mem_free 
> is large (given that there is enough swap).

Then we should place upper limit on the amount of used swap as well.

Something as MIN(MemFree/2, SwapFree, 1GB) to be used for the limit and
abort the test if this number is to small?

Apart from that the root memory cgroup should be better named something
as ltp_stres_root so that it's clear where it came from...

-- 
Cyril Hrubis
chrubis@suse.cz