Re: [PATCH 3/8] net: consolidate memcg socket buffer tracking and accounting

From	Vladimir Davydov <vdavydov@virtuozzo.com>
Newsgroups	linux.kernel
Subject	Re: [PATCH 3/8] net: consolidate memcg socket buffer tracking and accounting
Date	2015-10-22 20:50 +0200
Message-ID	<qmt61-2wa-1@gated-at.bofh.it> (permalink)
References	<qmfFL-87d-1@gated-at.bofh.it> <qmfFM-87d-21@gated-at.bofh.it>
Organization	linux.* mail to news gateway

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On Thu, Oct 22, 2015 at 12:21:31AM -0400, Johannes Weiner wrote:
> The tcp memory controller has extensive provisions for future memory
> accounting interfaces that won't materialize after all. Cut the code
> base down to what's actually used, now and in the likely future.
> 
> - There won't be any different protocol counters in the future, so a
>   direct sock->sk_memcg linkage is enough. This eliminates a lot of
>   callback maze and boilerplate code, and restores most of the socket
>   allocation code to pre-tcp_memcontrol state.
> 
> - There won't be a tcp control soft limit, so integrating the memcg

In fact, the code is ready for the "soft" limit (I mean min, pressure,
max tuple), it just lacks a knob.

>   code into the global skmem limiting scheme complicates things
>   unnecessarily. Replace all that with simple and clear charge and
>   uncharge calls--hidden behind a jump label--to account skb memory.
> 
> - The previous jump label code was an elaborate state machine that
>   tracked the number of cgroups with an active socket limit in order
>   to enable the skmem tracking and accounting code only when actively
>   necessary. But this is overengineered: it was meant to protect the
>   people who never use this feature in the first place. Simply enable
>   the branches once when the first limit is set until the next reboot.
> 
...
> @@ -1136,9 +1090,6 @@ static inline bool sk_under_memory_pressure(const struct sock *sk)
>  	if (!sk->sk_prot->memory_pressure)
>  		return false;
>  
> -	if (mem_cgroup_sockets_enabled && sk->sk_cgrp)
> -		return !!sk->sk_cgrp->memory_pressure;
> -

AFAIU, now we won't shrink the window on hitting the limit, i.e. this
patch subtly changes the behavior of the existing knobs, potentially
breaking them.

Thanks,
Vladimir
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Thread

[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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