From: Tejun Heo <tj@kernel.org>
To: Balbir Singh <bsingharora@gmail.com>
Cc: Michal Hocko <mhocko@kernel.org>,
linux-mm@kvack.org, linuxppc-dev@lists.ozlabs.org,
Andrew Morton <akpm@linux-foundation.org>,
Johannes Weiner <hannes@cmpxchg.org>,
Vladimir Davydov <vdavydov.dev@gmail.com>
Subject: Re: [mm v2 0/3] Support memory cgroup hotplug
Date: Mon, 28 Nov 2016 16:10:14 -0500 [thread overview]
Message-ID: <20161128211014.GB12143@htj.duckdns.org> (raw)
In-Reply-To: <962ac541-55c4-de09-59a3-4947c394eee6@gmail.com>
On Thu, Nov 24, 2016 at 12:05:12AM +1100, Balbir Singh wrote:
> On my desktop NODES_SHIFT is 6, many distro kernels have it a 9. I've known
> of solutions that use fake NUMA for partitioning and need as many nodes as
> possible.
It was a crude kludge that people used before memcg. If people still
use it, that's fine but we don't want to optimize / make code
complicated for it, so let's please put away this part of
justification.
It's understandable that some kernels want to have large NODES_SHIFT
to support wide range of configurations but if that makes wastage too
high, the simpler solution is updating the users to use the rumtime
detected possible number / mask instead of the compile time
NODES_SHIFT. Note that we do exactly the same thing for per-cpu
things - we configure high max but do all operations on what's
possible on the system.
NUMA code already has possible detection. Why not simply make memcg
use those instead of MAX_NUMNODES like how we use nr_cpu_ids instead
of NR_CPUS?
Thanks.
--
tejun
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next prev parent reply other threads:[~2016-11-28 21:10 UTC|newest]
Thread overview: 15+ messages / expand[flat|nested] mbox.gz Atom feed top
2016-11-23 4:36 [mm v2 0/3] Support memory cgroup hotplug Balbir Singh
2016-11-23 4:36 ` [mm v2 1/3] mm: Add basic infrastructure for memcg hotplug support Balbir Singh
2016-11-23 4:36 ` [mm v2 2/3] mm: Move operations to hotplug callbacks Balbir Singh
2016-11-23 4:36 ` [mm v2 3/3] powerpc/mm: fix node_possible_map limitations Balbir Singh
2016-11-23 7:25 ` [mm v2 0/3] Support memory cgroup hotplug Michal Hocko
2016-11-23 7:50 ` Balbir Singh
2016-11-23 8:07 ` Michal Hocko
2016-11-23 8:37 ` Balbir Singh
2016-11-23 9:28 ` Michal Hocko
2016-11-23 13:05 ` Balbir Singh
2016-11-23 13:22 ` Michal Hocko
2016-11-28 21:10 ` Tejun Heo [this message]
2016-11-29 0:09 ` Balbir Singh
2016-11-29 0:42 ` Tejun Heo
2016-11-29 4:57 ` Balbir Singh
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