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Date:   Wed, 7 Apr 2021 13:54:48 +0200
From:   Michal Hocko <mhocko@suse.com>
To:     Bharata B Rao <bharata@linux.ibm.com>
Cc:     akpm@linux-foundation.org, linux-kernel@vger.kernel.org,
        linux-mm@kvack.org, linux-fsdevel@vger.kernel.org,
        aneesh.kumar@linux.ibm.com
Subject: Re: High kmalloc-32 slab cache consumption with 10k containers
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References: <20210405054848.GA1077931@in.ibm.com>
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On Mon 05-04-21 11:18:48, Bharata B Rao wrote:
> Hi,
> 
> When running 10000 (more-or-less-empty-)containers on a bare-metal Power9
> server(160 CPUs, 2 NUMA nodes, 256G memory), it is seen that memory
> consumption increases quite a lot (around 172G) when the containers are
> running. Most of it comes from slab (149G) and within slab, the majority of
> it comes from kmalloc-32 cache (102G)

Is this 10k cgroups a testing enviroment or does anybody really use that
in production? I would be really curious to hear how that behaves when
those containers are not idle. E.g. global memory reclaim iterating over
10k memcgs will likely be very visible. I do remember playing with
similar setups few years back and the overhead was very high.
-- 
Michal Hocko
SUSE Labs