linux-kernel - Re: [PATCH v3] zram: break the strict dependency from lzo

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Message-ID: <CALjTZvbf4qK6SHEe7OhkTC_o7kaY4oOKQ+kk-D2OUq_ULsYAqQ@mail.gmail.com>
Date:   Tue, 27 Oct 2020 08:39:51 +0000
From:   Rui Salvaterra <rsalvaterra@...il.com>
To:     Sergey Senozhatsky <sergey.senozhatsky.work@...il.com>
Cc:     minchan@...nel.org, ngupta@...are.org,
        linux-kernel@...r.kernel.org, linux-block@...r.kernel.org
Subject: Re: [PATCH v3] zram: break the strict dependency from lzo

Hi, Sergey,

On Tue, 27 Oct 2020 at 01:22, Sergey Senozhatsky
<sergey.senozhatsky.work@...il.com> wrote:
>
> Honestly, I'm not entirely excited. lzo is a fallback compression
> algorithm. If you want to use zram with something else thenconfigure
> zram to use something else. What do all these #if/#elif buy us?

The idea is to allow us to select a single compression algorithm at
build time, if we're sure to use something other than lzo. The status
quo only allows us to select additional algorithms, as lzo is a hard
dependency. I dislike the "iffery" as much as the next guy, but in
this case the default selection stops being static (as lzo may not be
available at run time), so we have to fall back to an algorithm which
is enabled, otherwise zram won't work out of the box (we'd always need
to choose the algorithm manually in sysfs).
Personally, I always use zram with zstd, and the only lzo dependency I
have is zram. Disabling lzo saves me about 3 kiB in the final
(xz-compressed) vmlinuz image. It's not much, for sure, but when your
total storage is 4 MiB (and your RAM is 32 MiB), every bit counts. :)

Thanks,
Rui