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

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Message-ID: <D01CD6BA-C12D-46AB-8AC1-F03A114FC055@fb.com>
Date:   Fri, 25 Aug 2017 18:55:44 +0000
From:   Nick Terrell <terrelln@...com>
To:     Minchan Kim <minchan@...nel.org>,
        Sergey Senozhatsky <sergey.senozhatsky@...il.com>
CC:     Sergey Senozhatsky <sergey.senozhatsky.work@...il.com>,
        Andrew Morton <akpm@...ux-foundation.org>,
        "linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
        Yann Collet <cyan@...com>
Subject: Re: [PATCH] zram: add zstd to the supported algorithms list

On 8/24/17, 9:51 PM, "Minchan Kim" <minchan@...nel.org> wrote:
>Off-topic:
>
>In all ways, zstd beats deflate. Nick, Right?

Yeah. Since all LZ compression algorithms are heuristics, there are some
rare cases where zlib beats zstd in compression ratio by a bit, but never
speed. In all cases where we've deployed zstd, we've seen aggregate
compression ratio improvements over zlib, and expect the same here.

>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?