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From:   yong w <yongw.pur@gmail.com>
Date:   Sat, 15 May 2021 23:33:29 +0800
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Subject: How to calculate available memory when zram is used?
To:     linux-kernel@vger.kernel.org, minchan@kernel.org,
        ngupta@vflare.org, sergey.senozhatsky.work@gmail.com
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How to calculate available memory when zram is used?
Available+Swap free memeory is obviously bigger than I actually can
use, because zram can compress memory by compression algorithm and
zram compressed data will occupy memeory too.
Is there any way to calculate available memory accurately?

I think of a way is to count the compression rate of zram in the
kernel. The available memory  is calculated as follows:
available + swapfree - swapfree * compress ratio
Is it reasonable?