From: valdis.kletnieks@vt.edu
To: "Austin S. Hemmelgarn" <ahferroin7@gmail.com>
Cc: Adam Borowski <kilobyte@angband.pl>,
Pintu Agarwal <pintu.ping@gmail.com>,
linux-mm@kvack.org, open list <linux-kernel@vger.kernel.org>,
kernelnewbies@kernelnewbies.org
Subject: Re: Creating compressed backing_store as swapfile
Date: Mon, 05 Nov 2018 11:53:56 -0500 [thread overview]
Message-ID: <83467.1541436836@turing-police.cc.vt.edu> (raw)
In-Reply-To: <6a1f57b6-503c-48a2-689b-3c321cd6d29f@gmail.com>
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On Mon, 05 Nov 2018 11:28:49 -0500, "Austin S. Hemmelgarn" said:
> Also, it's probably worth noting that BTRFS doesn't need to decompress
> the entire file to read or write blocks in the middle, it splits the
> file into 128k blocks and compresses each of those independent of the
> others, so it can just decompress the 128k block that holds the actual
> block that's needed.
Presumably it does something sane with block allocation for the now-compressed
128K that's presumably much smaller. Also, that limits the damage from writing to
the middle of a compression unit....
That *does* however increase the memory requirement - you can OOM or
deadlock if your read/write from the swap needs an additional 128K for the
compression buffer at an inconvenient time...
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next prev parent reply other threads:[~2018-11-05 16:54 UTC|newest]
Thread overview: 10+ messages / expand[flat|nested] mbox.gz Atom feed top
2018-11-05 15:01 Creating compressed backing_store as swapfile Pintu Agarwal
2018-11-05 15:58 ` Adam Borowski
2018-11-05 16:07 ` Austin S. Hemmelgarn
2018-11-05 16:14 ` valdis.kletnieks
2018-11-05 16:28 ` Austin S. Hemmelgarn
2018-11-05 16:53 ` valdis.kletnieks [this message]
2018-11-05 16:55 ` Austin S. Hemmelgarn
2018-11-08 9:51 ` Pintu Agarwal
2018-11-05 16:12 ` valdis.kletnieks
2018-11-08 9:46 ` Pintu Agarwal
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