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From: Michal Hocko <mhocko@suse.com>
To: Shakeel Butt <shakeelb@google.com>
Cc: Arjun Roy <arjunroy@google.com>,
	Johannes Weiner <hannes@cmpxchg.org>,
	Arjun Roy <arjunroy.kdev@gmail.com>,
	Andrew Morton <akpm@linux-foundation.org>,
	David Miller <davem@davemloft.net>,
	netdev <netdev@vger.kernel.org>,
	Linux Kernel Mailing List <linux-kernel@vger.kernel.org>,
	Cgroups <cgroups@vger.kernel.org>, Linux MM <linux-mm@kvack.org>,
	Eric Dumazet <edumazet@google.com>,
	Soheil Hassas Yeganeh <soheil@google.com>,
	Jakub Kicinski <kuba@kernel.org>, Yang Shi <shy828301@gmail.com>,
	Roman Gushchin <guro@fb.com>
Subject: Re: [mm, net-next v2] mm: net: memcg accounting for TCP rx zerocopy
Date: Wed, 24 Mar 2021 22:56:44 +0100	[thread overview]
Message-ID: <YFu1nO3yYT5VVebo@dhcp22.suse.cz> (raw)
In-Reply-To: <CALvZod6HQ=bG2K1YPofmD=7q3OX+FoRHbzLHcGAMSKOXtfn9dw@mail.gmail.com>

On Wed 24-03-21 13:53:34, Shakeel Butt wrote:
[...]
> > Given that's the case, the options seem to be:
> > 1) Use a page flag - with the downside that they are a severely
> > limited resource,
> > 2) Use some bits inside page->memcg_data - this I believe Johannes had
> > reasons against, and it isn't always the case that MEMCG support is
> > enabled.
> > 3) Use compound_dtor - but I think this would have problems for the
> > prior reasons.
> 
> I don't think Michal is suggesting to use PageCompound() or
> PageHead(). He is suggesting to add a more general page flag
> (PageHasDestructor) and corresponding page->dtor, so other potential
> users can use it too.

Yes, that is eaxactly my point. If there is a page flag to use for a
specific destruction then we can use an already existing scheme. I have
fully digested Johannes' other reply so I might be still missing
something but fundamentally if sombody knows that the particular part of
the page is not used (most really should) then the page can claim
destructor by a flag and the freeing routine would just call that
callback. Or is there any reason why othe subsystems outside of
networking couldn't claim their own callback?
-- 
Michal Hocko
SUSE Labs


  reply	other threads:[~2021-03-24 21:56 UTC|newest]

Thread overview: 28+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2021-03-16  4:16 [mm, net-next v2] mm: net: memcg accounting for TCP rx zerocopy Arjun Roy
2021-03-16  4:20 ` Arjun Roy
2021-03-16  4:29   ` Shakeel Butt
2021-03-16  6:22     ` Arjun Roy
2021-03-16  6:28       ` Arjun Roy
2021-03-16 21:02         ` Jakub Kicinski
2021-03-16 10:26 ` Johannes Weiner
2021-03-17  6:05   ` Arjun Roy
2021-03-17 22:12     ` Johannes Weiner
2021-03-22 21:35       ` Arjun Roy
2021-03-23 17:01         ` Johannes Weiner
2021-03-23 18:42           ` Arjun Roy
2021-03-24 18:25             ` Shakeel Butt
2021-03-24 22:21               ` Arjun Roy
2021-03-23 14:34       ` Michal Hocko
2021-03-23 18:47         ` Arjun Roy
2021-03-24  9:12           ` Michal Hocko
2021-03-24 20:39             ` Arjun Roy
2021-03-24 20:53               ` Shakeel Butt
2021-03-24 21:56                 ` Michal Hocko [this message]
2021-03-24 21:24             ` Johannes Weiner
2021-03-24 22:49               ` Arjun Roy
2021-03-25  9:02                 ` Michal Hocko
2021-03-25 16:47                   ` Johannes Weiner
2021-03-25 17:50                     ` Michal Hocko
  -- strict thread matches above, loose matches on Subject: below --
2021-03-16  1:30 Arjun Roy
2021-03-18  3:21 ` Andrew Morton
2021-03-22 21:19   ` Arjun Roy

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