linux-kernel - Re: [External] Re: [PATCH] mm: memcontrol: localize mem_cgroup_sockets

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Message-ID: <CAMZfGtXE1DaDXSOWObaJDTxUH2zB2hjfKoX38Y2oKgNaDkyoCA@mail.gmail.com>
Date:   Tue, 13 Oct 2020 00:04:44 +0800
From:   Muchun Song <songmuchun@...edance.com>
To:     Johannes Weiner <hannes@...xchg.org>
Cc:     David Miller <davem@...emloft.net>, kuba@...nel.org,
        Eric Dumazet <edumazet@...gle.com>,
        Michal Hocko <mhocko@...nel.org>,
        Vladimir Davydov <vdavydov.dev@...il.com>,
        Andrew Morton <akpm@...ux-foundation.org>,
        kuznet@....inr.ac.ru, yoshfuji@...ux-ipv6.org,
        Shakeel Butt <shakeelb@...gle.com>,
        Roman Gushchin <guro@...com>,
        Joonsoo Kim <iamjoonsoo.kim@....com>, laoar.shao@...il.com,
        Chris Down <chris@...isdown.name>,
        Daniel Borkmann <daniel@...earbox.net>,
        Martin KaFai Lau <kafai@...com>,
        Alexei Starovoitov <ast@...nel.org>, jakub@...udflare.com,
        linmiaohe@...wei.com, Kees Cook <keescook@...omium.org>,
        LKML <linux-kernel@...r.kernel.org>,
        Networking <netdev@...r.kernel.org>,
        Cgroups <cgroups@...r.kernel.org>,
        Linux Memory Management List <linux-mm@...ck.org>
Subject: Re: [External] Re: [PATCH] mm: memcontrol: localize
 mem_cgroup_sockets_enabled() check

On Mon, Oct 12, 2020 at 9:59 PM Johannes Weiner <hannes@...xchg.org> wrote:
>
> On Sat, Oct 10, 2020 at 06:45:21PM +0800, Muchun Song wrote:
> > Move the mem_cgroup_sockets_enabled() checks into memcg socket charge
> > or uncharge functions, so the users don't have to explicitly check that
> > condition.
> >
> > This is purely code cleanup patch without any functional change. But
> > move the sk_memcg member of the sock structure to the CONFIG_MEMCG
> > scope.
> >
> > Signed-off-by: Muchun Song <songmuchun@...edance.com>
> > ---
> >  include/linux/memcontrol.h      | 78 ++++++++++++++++++++++++++-------
> >  include/net/sock.h              |  5 ++-
> >  include/net/tcp.h               |  3 +-
> >  mm/memcontrol.c                 | 43 +++++++++++++-----
> >  net/core/sock.c                 | 15 +++----
> >  net/ipv4/inet_connection_sock.c |  6 +--
> >  net/ipv4/tcp_output.c           |  3 +-
> >  7 files changed, 111 insertions(+), 42 deletions(-)
>
> Hm, this is almost 3 times as much code.
>
> The sk_memcg saving on !CONFIG_MEMCG is somewhat nice, but it's not
> clear how many users would benefit here. And it adds ifdefs in code.

The 'ifdefs in code' means the initialization of sk_memcg in the sk_clone_lock?
If yes, we can add a new inline initialization function to avoid this.

>
> Also memcg code now has to know about struct sock.

Without this patch, the memcg code also has to know about struct sock.
You can see the code of  mem_cgroup_sk_alloc and mem_cgroup_sk_free.

Thanks.

>
> I'm not quite sure that this is an overall improvement.



-- 
Yours,
Muchun