Re: [PATCH 4/5] mm: zswap: add basic meminfo and vmstat coverage

From: Suleiman Souhlal <suleiman@google.com>
To: Shakeel Butt <shakeelb@google.com>
Cc: Yang Shi <shy828301@gmail.com>,
	Johannes Weiner <hannes@cmpxchg.org>,
	Minchan Kim <minchan@kernel.org>,
	Andrew Morton <akpm@linux-foundation.org>,
	Michal Hocko <mhocko@suse.com>, Roman Gushchin <guro@fb.com>,
	Seth Jennings <sjenning@redhat.com>,
	Dan Streetman <ddstreet@ieee.org>, Linux MM <linux-mm@kvack.org>,
	Cgroups <cgroups@vger.kernel.org>,
	LKML <linux-kernel@vger.kernel.org>,
	Kernel Team <kernel-team@fb.com>
Subject: Re: [PATCH 4/5] mm: zswap: add basic meminfo and vmstat coverage
Date: Fri, 6 May 2022 07:24:51 +0900	[thread overview]
Message-ID: <CABCjUKAoTmqvyBbFH7A188s8Hwi1XbLgfb6znzgFOuRWBMBxig@mail.gmail.com> (raw)
In-Reply-To: <CALvZod5CReJZeGxkX9i6k7+R+3kF5dikXx9akbiP_L0j4Qu=6A@mail.gmail.com>

On Fri, May 6, 2022 at 4:33 AM Shakeel Butt <shakeelb@google.com> wrote:
>
> On Thu, Apr 28, 2022 at 9:54 AM Yang Shi <shy828301@gmail.com> wrote:
> >
> [...]
> > > Yes, we have some modifications to zswap to make it work without any
> > > backing real swap. Though there is a future plan to move to zram
> > > eventually.
> >
> > Interesting, if so why not just simply use zram?
> >
>
> Historical reasons. When we started trying out the zswap, I think zram
> was still in staging or not stable enough (Suleiman can give a better
> answer).

One of the reasons we chose zswap instead of zram is that zswap can
reject pages.
Also, we wanted to have per-memcg pools, which zswap made much easier to do.

-- Suleiman