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From: Mitch Harder <mitch.harder@sabayonlinux.org>
To: Philip Worrall <philip.worrall@googlemail.com>
Cc: linux-btrfs <linux-btrfs@vger.kernel.org>
Subject: Re: [PATCH 0/8] Add support for LZ4 compression
Date: Mon, 2 Jun 2014 17:04:02 -0500	[thread overview]
Message-ID: <CAKcLGm9nHmmN1oAe2AQO6aNB8R6nmqvwjUv+9ytiUFD5LWG3nw@mail.gmail.com> (raw)
In-Reply-To: <1401580116-10458-1-git-send-email-philip.worrall@googlemail.com>

On Sat, May 31, 2014 at 6:48 PM, Philip Worrall
<philip.worrall@googlemail.com> wrote:
> LZ4 is a lossless data compression algorithm that is focused on
> compression and decompression speed. LZ4 gives a slightly worse
> compression ratio compared with LZO (and much worse than Zlib)
> but compression speeds are *generally* similar to LZO.
> Decompression tends to be much faster under LZ4 compared
> with LZO hence it makes more sense to use LZ4 compression
> when your workload involves a higher proportion of reads.
>
> The following patch set adds LZ4 compression support to BTRFS
> using the existing kernel implementation. It is based on the
> changeset for LZO support in 2011. Once a filesystem has been
> mounted with LZ4 compression enabled older versions of BTRFS
> will be unable to read it. This implementation is however
> backwards compatible with filesystems that currently use
> LZO or Zlib compression. Existing data will remain unchanged
> but any new files that you create will be compressed with LZ4.
>
> Usage:
> Apply the following 8 patches to the current git tree
> (as of 20140531) and compile/load the btrfs module.
>
> # mount -t btrfs -o compress=lz4 device mountpoint
>
> or
>
> # mount -t btrfs -o compress-force=lz4 device mountpoint
>

I gave this patch-set a preliminary test, and there were no obvious
signs of corruption.

I was unable to run btrfsck or xfstests since btrfs-progs is not yet
aware of lz4, so my testing should be considered superficial.

One comment:  IMHO, it would make sense to implement lz4 and lz4hc at
the same time.  Since both are now in the kernel, I assume we would go
that direction eventually anyways, unless there are some wrinkles
around lz4hc I don't fully appreciate.  So we might as well conserve
the kernel INCOMPAT flag.

  parent reply	other threads:[~2014-06-02 22:04 UTC|newest]

Thread overview: 13+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2014-05-31 23:48 [PATCH 0/8] Add support for LZ4 compression Philip Worrall
2014-05-31 23:48 ` [PATCH 1/8] Btrfs: Add kernel config options for LZ4 Philip Worrall
2014-05-31 23:48 ` [PATCH 2/8] Btrfs: Add lz4.c to the Makefile Philip Worrall
2014-05-31 23:48 ` [PATCH 3/8] Btrfs: Add lz4 compression to avaialble compression ops Philip Worrall
2014-05-31 23:48 ` [PATCH 4/8] Btrfs: Add definition for external lz4 compression struct Philip Worrall
2014-05-31 23:48 ` [PATCH 5/8] Btrfs: Add feature flags for LZ4 support Philip Worrall
2014-05-31 23:48 ` [PATCH 6/8] Btrfs: Ensure LZ4 feature flags are set when mounting with LZ4 Philip Worrall
2014-05-31 23:48 ` [PATCH 7/8] Btrfs: Add lz4 compression/decompression struct ops Philip Worrall
2014-05-31 23:48 ` [PATCH 8/8] Btrfs: Check for compress=lz4 in mount options Philip Worrall
2014-06-02 22:04 ` Mitch Harder [this message]
2014-06-03 15:53 ` [PATCH 0/8] Add support for LZ4 compression David Sterba
2014-06-04 14:00   ` Chris Mason
2014-06-12  8:47     ` David Sterba

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