Return-Path: <linux-kernel-owner@vger.kernel.org>
Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand
        id S1754728AbdHYHtS (ORCPT <rfc822;w@1wt.eu>);
        Fri, 25 Aug 2017 03:49:18 -0400
Received: from mail-pg0-f67.google.com ([74.125.83.67]:34556 "EHLO
        mail-pg0-f67.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org
        with ESMTP id S1754521AbdHYHtQ (ORCPT
        <rfc822;linux-kernel@vger.kernel.org>);
        Fri, 25 Aug 2017 03:49:16 -0400
Date: Fri, 25 Aug 2017 16:45:33 +0900
From: Sergey Senozhatsky <sergey.senozhatsky@gmail.com>
To: Minchan Kim <minchan@kernel.org>
Cc: Sergey Senozhatsky <sergey.senozhatsky.work@gmail.com>,
        Sergey Senozhatsky <sergey.senozhatsky@gmail.com>,
        Andrew Morton <akpm@linux-foundation.org>,
        linux-kernel@vger.kernel.org, Nick Terrell <terrelln@fb.com>,
        Herbert Xu <herbert@gondor.apana.org.au>
Subject: Re: [PATCH] zram: add zstd to the supported algorithms list
Message-ID: <20170825074533.GB5535@tigerII.localdomain>
References: <20170824014936.4738-1-sergey.senozhatsky@gmail.com>
 <20170824043038.GA13922@bgram>
 <20170824140440.GA5535@tigerII.localdomain>
 <20170825045036.GA26819@blaptop>
 <20170825050644.GB5876@jagdpanzerIV.localdomain>
 <20170825053606.GA27787@blaptop>
MIME-Version: 1.0
Content-Type: text/plain; charset=us-ascii
Content-Disposition: inline
In-Reply-To: <20170825053606.GA27787@blaptop>
User-Agent: Mutt/1.8.3 (2017-05-23)
Sender: linux-kernel-owner@vger.kernel.org
List-ID: <linux-kernel.vger.kernel.org>
X-Mailing-List: linux-kernel@vger.kernel.org
Content-Length: 1100
Lines: 31

On (08/25/17 14:36), Minchan Kim wrote:
[..]
> > hmmm... frankly, I don't think it would confuse anyone. the code is
> > there - compiled - anyway, and the module is visible in /proc/crypto
> > etc. if we will make it unavailable in zram then this can be confusing,
> > probably... if anyone ever pays any attention at all. my guess is that
> > people look what's in /sys/block/zram0/comp_algorithm just once, then
> > they set up a create-zram script/systemd unit file/etc. and forget
> > about it.
> 
> Although we don't show "deflate", zram still supports

right. I forgot about it :) [... and I have authored that code]

> Again, my point is that I want to show limited representative compression
> (high speed/low comp, low speed/high comp, mid/mid) algorithm via
> /sys/block/zram0/comp_algorithm rather than adding new entry whenever
> new algorithm is added on.

ok, will send out a patch set.



that may lead to a bigger/more general question:

- if zstd is so much better, then do we need deflate/inflate at all in
  the kernel? may be zstd can replace it?

what do you think, Nick?

	-ss