linux-kernel - Re: [PATCH RFC 4/7] zram: Introduce recompress sysfs knob

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Message-ID: <Yx8EbYy2QP1BgS6O@google.com>
Date:   Mon, 12 Sep 2022 19:05:33 +0900
From:   Sergey Senozhatsky <senozhatsky@...omium.org>
To:     Minchan Kim <minchan@...nel.org>
Cc:     Andrew Morton <akpm@...ux-foundation.org>,
        Nitin Gupta <ngupta@...are.org>, linux-kernel@...r.kernel.org,
        linux-mm@...ck.org, Sergey Senozhatsky <senozhatsky@...omium.org>
Subject: Re: [PATCH RFC 4/7] zram: Introduce recompress sysfs knob

On (22/09/05 17:23), Sergey Senozhatsky wrote:
[..]
> +	/*
> +	 * Either a compression error or we failed to compressed the object
> +	 * in a way that will save us memory. Mark object as "recompressed"
> +	 * if it's huge, so that we don't try to recompress it again. Ideally
> +	 * we want to set some bit for all such objects, but we for now do so
> +	 * only for huge ones (we are out of bits in flags on 32-bit systems).
> +	 */

This limitation goes away once we move ZRAM_FLAG_SHIFT to
more reasonable value. I can introduce one more pageflag
that will be set for objects that cannot be compressed by
either compression algorithm.