Received-SPF: pass (google.com: domain of linux-kernel-owner@vger.kernel.org designates 23.128.96.18 as permitted sender) client-ip=23.128.96.18;
MIME-Version: 1.0
References: <20200603230303.kSkT62Lb5%akpm@linux-foundation.org>
 <a60f7866-3b32-7a0e-5d0a-a48d77f845a8@linux.alibaba.com> <20200609144551.GA452252@cmpxchg.org>
In-Reply-To: <20200609144551.GA452252@cmpxchg.org>
From:   Joonsoo Kim <js1304@gmail.com>
Date:   Wed, 10 Jun 2020 14:23:57 +0900
Message-ID: <CAAmzW4OrmCBQC05E6Kr-pLw3VU=cthzZCpfEzDabhO5vTaq8KA@mail.gmail.com>
Subject: Re: [patch 113/131] mm: balance LRU lists based on relative thrashing
To:     Johannes Weiner <hannes@cmpxchg.org>
Cc:     Alex Shi <alex.shi@linux.alibaba.com>,
        LKML <linux-kernel@vger.kernel.org>,
        Andrew Morton <akpm@linux-foundation.org>,
        Joonsoo Kim <iamjoonsoo.kim@lge.com>,
        Linux Memory Management List <linux-mm@kvack.org>,
        Michal Hocko <mhocko@suse.com>,
        =?UTF-8?B?6rmA66+87LCs?= <minchan@kernel.org>,
        mm-commits@vger.kernel.org, Rik van Riel <riel@surriel.com>,
        Linus Torvalds <torvalds@linux-foundation.org>
Content-Type: text/plain; charset="UTF-8"
Content-Transfer-Encoding: quoted-printable
Sender: linux-kernel-owner@vger.kernel.org
Precedence: bulk

2020=EB=85=84 6=EC=9B=94 9=EC=9D=BC (=ED=99=94) =EC=98=A4=ED=9B=84 11:46, J=
ohannes Weiner <hannes@cmpxchg.org>=EB=8B=98=EC=9D=B4 =EC=9E=91=EC=84=B1:
>
> On Tue, Jun 09, 2020 at 05:15:33PM +0800, Alex Shi wrote:
> >
> >
> > =E5=9C=A8 2020/6/4 =E4=B8=8A=E5=8D=887:03, Andrew Morton =E5=86=99=E9=
=81=93:
> > >
> > > +   /* XXX: Move to lru_cache_add() when it supports new vs putback *=
/
> >
> > Hi Hannes,
> >
> > Sorry for a bit lost, would you like to explain a bit more of your idea=
 here?
> >
> > > +   spin_lock_irq(&page_pgdat(page)->lru_lock);
> > > +   lru_note_cost(page);
> > > +   spin_unlock_irq(&page_pgdat(page)->lru_lock);
> > > +
> >
> >
> > What could we see here w/o the lru_lock?
>
> It'll just be part of the existing LRU locking in
> pagevec_lru_move_fn(), when the new pages are added to the LRU in
> batch. See this older patch for example:
>
> https://lore.kernel.org/linux-mm/20160606194836.3624-6-hannes@cmpxchg.org=
/
>
> I didn't include it in this series to reduce conflict with Joonsoo's
> WIP series that also operates in this area and does something similar:

Thanks!

> https://lkml.org/lkml/2020/4/3/63

I haven't completed the rebase of my series but I guess that referenced pat=
ch
"https://lkml.org/lkml/2020/4/3/63" would be removed in the next version.

Before the I/O cost model, a new anonymous page contributes to the LRU recl=
aim
balance. But, now, a new anonymous page doesn't contributes to the I/O cost
so this adjusting patch would not be needed anymore.

If anyone wants to change this part,
"/* XXX: Move to lru_cache_add() when it supports new vs putback */", feel =
free
to do it.

Thanks.