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Re: [PATCH 5/8] mm: memcontrol: account socket memory on unified hierarchy

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On Mon 26-10-15 12:56:19, Johannes Weiner wrote:
[...]
> Now you could argue that there might exist specialized workloads that
> need to account anonymous pages and page cache, but not socket memory
> buffers.

Exactly, and there are loads doing this. Memcg groups are also created to
limit anon/page cache consumers to not affect the others running on
the system (basically in the root memcg context from memcg POV) which
don't care about tracking and they definitely do not want to pay for an
additional overhead. We should definitely be able to offer a global
disable knob for them. The same applies to kmem accounting in general.

I do understand with having the accounting enabled by default after we
are reasonably sure that both kmem/tcp are stable enough (which I am
not convinced about yet to be honest) but there will be always special
loads which simply do not care about kmem/tcp accounting and rather pay
a global balancing price (even OOM) rather than a permanent price. And
they should get a way to opt-out.

> Or any other combination of pick-and-choose consumers. But
> honestly, nowadays all our paths are lockless, and the counting is an
> atomic-add-return with a per-cpu batch cache.

You are still hooking into hot paths and there are users who want to
squeeze every single cycle from the HW.

> I don't think there is a compelling case for an elaborate interface
> to make individual memory consumers configurable inside the memory
> controller.

I do not think we need an elaborate interface. We just want to have
a global boot time knob to overwrite the default behavior. This is
few lines of code and it should give the sufficient flexibility.
-- 
Michal Hocko
SUSE Labs
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[PATCH 0/8] mm: memcontrol: account socket memory in unified hierarchy Johannes Weiner <hannes@cmpxchg.org> - 2015-10-22 06:30 +0200
  [PATCH 1/8] mm: page_counter: let page_counter_try_charge() return bool Johannes Weiner <hannes@cmpxchg.org> - 2015-10-22 06:30 +0200
    Re: [PATCH 1/8] mm: page_counter: let page_counter_try_charge()  return bool Michal Hocko <mhocko@kernel.org> - 2015-10-23 13:40 +0200
  [PATCH 6/8] mm: vmscan: simplify memcg vs. global shrinker invocation Johannes Weiner <hannes@cmpxchg.org> - 2015-10-22 06:30 +0200
    Re: [PATCH 6/8] mm: vmscan: simplify memcg vs. global shrinker  invocation Michal Hocko <mhocko@kernel.org> - 2015-10-23 15:30 +0200
  [PATCH 4/8] mm: memcontrol: prepare for unified hierarchy socket accounting Johannes Weiner <hannes@cmpxchg.org> - 2015-10-22 06:30 +0200
    Re: [PATCH 4/8] mm: memcontrol: prepare for unified hierarchy socket  accounting Michal Hocko <mhocko@kernel.org> - 2015-10-23 14:40 +0200
  [PATCH 5/8] mm: memcontrol: account socket memory on unified hierarchy Johannes Weiner <hannes@cmpxchg.org> - 2015-10-22 06:30 +0200
    Re: [PATCH 5/8] mm: memcontrol: account socket memory on unified  hierarchy Vladimir Davydov <vdavydov@virtuozzo.com> - 2015-10-22 20:50 +0200
    Re: [PATCH 5/8] mm: memcontrol: account socket memory on unified  hierarchy Michal Hocko <mhocko@kernel.org> - 2015-10-23 15:30 +0200
      Re: [PATCH 5/8] mm: memcontrol: account socket memory on unified  hierarchy David Miller <davem@davemloft.net> - 2015-10-23 15:50 +0200
        Re: [PATCH 5/8] mm: memcontrol: account socket memory on unified  hierarchy Johannes Weiner <hannes@cmpxchg.org> - 2015-10-26 18:00 +0100
          Re: [PATCH 5/8] mm: memcontrol: account socket memory on unified  hierarchy Michal Hocko <mhocko@kernel.org> - 2015-10-27 13:30 +0100
            Re: [PATCH 5/8] mm: memcontrol: account socket memory on unified  hierarchy David Miller <davem@davemloft.net> - 2015-10-27 14:40 +0100
            Re: [PATCH 5/8] mm: memcontrol: account socket memory on unified  hierarchy Johannes Weiner <hannes@cmpxchg.org> - 2015-10-27 16:50 +0100
              Re: [PATCH 5/8] mm: memcontrol: account socket memory on unified  hierarchy Michal Hocko <mhocko@kernel.org> - 2015-10-27 17:20 +0100
                Re: [PATCH 5/8] mm: memcontrol: account socket memory on unified  hierarchy Johannes Weiner <hannes@cmpxchg.org> - 2015-10-27 17:50 +0100
                Re: [PATCH 5/8] mm: memcontrol: account socket memory on unified  hierarchy David Miller <davem@davemloft.net> - 2015-10-28 01:30 +0100
                Re: [PATCH 5/8] mm: memcontrol: account socket memory on unified  hierarchy Johannes Weiner <hannes@cmpxchg.org> - 2015-10-28 04:10 +0100
                Re: [PATCH 5/8] mm: memcontrol: account socket memory on unified  hierarchy Michal Hocko <mhocko@kernel.org> - 2015-10-29 16:30 +0100
                Re: [PATCH 5/8] mm: memcontrol: account socket memory on unified  hierarchy Johannes Weiner <hannes@cmpxchg.org> - 2015-10-29 17:20 +0100
  [PATCH 2/8] mm: memcontrol: export root_mem_cgroup Johannes Weiner <hannes@cmpxchg.org> - 2015-10-22 06:30 +0200
    Re: [PATCH 2/8] mm: memcontrol: export root_mem_cgroup Michal Hocko <mhocko@kernel.org> - 2015-10-23 13:40 +0200
  [PATCH 7/8] mm: vmscan: report vmpressure at the level of reclaim activity Johannes Weiner <hannes@cmpxchg.org> - 2015-10-22 06:30 +0200
    Re: [PATCH 7/8] mm: vmscan: report vmpressure at the level of  reclaim activity Vladimir Davydov <vdavydov@virtuozzo.com> - 2015-10-22 20:50 +0200
    Re: [PATCH 7/8] mm: vmscan: report vmpressure at the level of  reclaim activity Michal Hocko <mhocko@kernel.org> - 2015-10-23 16:00 +0200
  [PATCH 8/8] mm: memcontrol: hook up vmpressure to socket pressure Johannes Weiner <hannes@cmpxchg.org> - 2015-10-22 06:30 +0200
    Re: [PATCH 8/8] mm: memcontrol: hook up vmpressure to socket pressure Vladimir Davydov <vdavydov@virtuozzo.com> - 2015-10-22 21:00 +0200
  [PATCH 3/8] net: consolidate memcg socket buffer tracking and accounting Johannes Weiner <hannes@cmpxchg.org> - 2015-10-22 06:30 +0200
    Re: [PATCH 3/8] net: consolidate memcg socket buffer tracking and  accounting Vladimir Davydov <vdavydov@virtuozzo.com> - 2015-10-22 20:50 +0200
      Re: [PATCH 3/8] net: consolidate memcg socket buffer tracking and  accounting Johannes Weiner <hannes@cmpxchg.org> - 2015-10-22 21:20 +0200
        Re: [PATCH 3/8] net: consolidate memcg socket buffer tracking and  accounting Vladimir Davydov <vdavydov@virtuozzo.com> - 2015-10-23 15:50 +0200
    Re: [PATCH 3/8] net: consolidate memcg socket buffer tracking and  accounting Michal Hocko <mhocko@kernel.org> - 2015-10-23 14:40 +0200
  Re: [PATCH 0/8] mm: memcontrol: account socket memory in unified  hierarchy Vladimir Davydov <vdavydov@virtuozzo.com> - 2015-10-22 20:50 +0200
    Re: [PATCH 0/8] mm: memcontrol: account socket memory in unified  hierarchy Johannes Weiner <hannes@cmpxchg.org> - 2015-10-26 18:30 +0100
      Re: [PATCH 0/8] mm: memcontrol: account socket memory in unified  hierarchy Vladimir Davydov <vdavydov@virtuozzo.com> - 2015-10-27 09:50 +0100
        Re: [PATCH 0/8] mm: memcontrol: account socket memory in unified  hierarchy Johannes Weiner <hannes@cmpxchg.org> - 2015-10-27 17:10 +0100
          Re: [PATCH 0/8] mm: memcontrol: account socket memory in unified  hierarchy Vladimir Davydov <vdavydov@virtuozzo.com> - 2015-10-28 09:30 +0100
            Re: [PATCH 0/8] mm: memcontrol: account socket memory in unified  hierarchy Johannes Weiner <hannes@cmpxchg.org> - 2015-10-28 20:00 +0100
              Re: [PATCH 0/8] mm: memcontrol: account socket memory in unified  hierarchy Vladimir Davydov <vdavydov@virtuozzo.com> - 2015-10-29 10:30 +0100
                Re: [PATCH 0/8] mm: memcontrol: account socket memory in unified  hierarchy Johannes Weiner <hannes@cmpxchg.org> - 2015-10-29 19:00 +0100

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