linux-kernel - Re: [PATCHv4 0/9] zram: Support multiple compression streams

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Date:   Thu, 3 Nov 2022 12:36:57 +0900
From:   Sergey Senozhatsky <senozhatsky@...omium.org>
To:     Minchan Kim <minchan@...nel.org>
Cc:     Sergey Senozhatsky <senozhatsky@...omium.org>,
        Andrew Morton <akpm@...ux-foundation.org>,
        Nitin Gupta <ngupta@...are.org>, linux-kernel@...r.kernel.org,
        linux-mm@...ck.org
Subject: Re: [PATCHv4 0/9] zram: Support multiple compression streams

Hi Minchan,

On (22/11/02 13:07), Minchan Kim wrote:
[..]
> Hi Sergey,
> 
> First of all, I am really sorry to attend the party too late.
> 
> I absolutely agree the feature is really useful and even I am
> thinking to support multiple comression trials on the fly for
> future. So I'd like to introduce the feature more general shape
> to be extended later so review will go.

On the fly recompression (from the same context) was what I had as
a first version (which was internal and was never published), and
we didn't like it at all. It's too limited, has zero flexibility,
zero extensibility and has too high of a price tag attached to it
(in terms of CPU cycles, power and time).

So we moved it to user-space (deferred context) and this unlocked
numerous possibilities: recompress only when we really need to and,
more importantly, can afford it; wire in numerous metrics: battery,
CPU load etc. And many more.