linux-kernel - Re: [PATCH] zram: add zstd to the supported algorithms list

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Date:   Fri, 25 Aug 2017 14:06:44 +0900
From:   Sergey Senozhatsky <sergey.senozhatsky.work@...il.com>
To:     Minchan Kim <minchan@...nel.org>
Cc:     Sergey Senozhatsky <sergey.senozhatsky@...il.com>,
        Sergey Senozhatsky <sergey.senozhatsky.work@...il.com>,
        Andrew Morton <akpm@...ux-foundation.org>,
        linux-kernel@...r.kernel.org, Nick Terrell <terrelln@...com>
Subject: Re: [PATCH] zram: add zstd to the supported algorithms list

On (08/25/17 13:50), Minchan Kim wrote:
[..]
> Thanks for the testing.
> Could you resend the patch with this test result with my acked-by?

ok.

> Acked-by: Minchan Kim <minchan@...nel.org>

thanks.

> Off-topic:
> 
> In all ways, zstd beats deflate. Nick, Right?
> 
> With zstd, I doubt we should show "deflate" to user. Many options just
> make user confused.
> The inflate have been there for representing high comp ratio but slower
> speed. However, zstd is better unconditionally compared to deflate
> so how about replacing deflate with zstd?
> 
> Sergey, what do you think about it?

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.

cryto API is just a wrapper and it calls lib/comp_foo to do the actual
work, and that lib/comp_foo *may be* can be implemented as a H/W (not
S/W) compressing backend. well, who knows.

	-ss