Received-SPF: pass (google.com: best guess record for domain of linux-kernel-owner@vger.kernel.org designates 209.132.180.67 as permitted sender) client-ip=209.132.180.67;
MIME-Version: 1.0
References: <20191010230414.647c29f34665ca26103879c4@gmail.com>
 <20191010232030.af6444879413e76a780cd27e@gmail.com> <20191014104717.GA43868@jagdpanzerIV>
In-Reply-To: <20191014104717.GA43868@jagdpanzerIV>
From:   Vitaly Wool <vitalywool@gmail.com>
Date:   Mon, 14 Oct 2019 13:52:57 +0200
Message-ID: <CAMJBoFOVs-W_RAocRmmFmf=zOwMBODxP7XFkrhcOHDii-aXkuQ@mail.gmail.com>
Subject: Re: [PATCH 3/3] zram: use common zpool interface
To:     Sergey Senozhatsky <sergey.senozhatsky.work@gmail.com>
Cc:     Linux-MM <linux-mm@kvack.org>,
        Andrew Morton <akpm@linux-foundation.org>,
        Dan Streetman <ddstreet@ieee.org>,
        Minchan Kim <minchan@kernel.org>,
        LKML <linux-kernel@vger.kernel.org>,
        Vlastimil Babka <vbabka@suse.cz>,
        Shakeel Butt <shakeelb@google.com>,
        Henry Burns <henrywolfeburns@gmail.com>,
        "Theodore Ts'o" <tytso@thunk.org>
Content-Type: text/plain; charset="UTF-8"
Sender: linux-kernel-owner@vger.kernel.org
Precedence: bulk

On Mon, Oct 14, 2019 at 12:49 PM Sergey Senozhatsky
<sergey.senozhatsky.work@gmail.com> wrote:
>
> On (10/10/19 23:20), Vitaly Wool wrote:
> [..]
> >  static const char *default_compressor = "lzo-rle";
> >
> > +#define BACKEND_PAR_BUF_SIZE 32
> > +static char backend_par_buf[BACKEND_PAR_BUF_SIZE];
>
> We can have multiple zram devices (zram0 .. zramN), I guess it
> would make sense not to force all devices to use one particular
> allocator (e.g. see comp_algorithm_store()).
>
> If the motivation for the patch set is that zsmalloc does not
> perform equally well for various data access patterns, then the
> same is true for any other allocator. Thus, I think, we need to
> have a per-device 'allocator' knob.

We were thinking here in per-SoC terms basically, but this is a valid
point. Since zram has a well-established sysfs per-device
configuration interface, backend choice better be moved there. Agree?

~Vitaly