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Illumos #3035 LZ4 compression support in ZFS and GRUB

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3035 LZ4 compression support in ZFS and GRUB

Reviewed by: Matthew Ahrens <mahrens@delphix.com>
Reviewed by: Christopher Siden <christopher.siden@delphix.com>
Reviewed by: George Wilson <george.wilson@delphix.com>
Approved by: Christopher Siden <csiden@delphix.com>

References:
  illumos/illumos-gate@a6f561b4ae
  https://www.illumos.org/issues/3035
  http://wiki.illumos.org/display/illumos/LZ4+Compression+In+ZFS

This patch has been slightly modified from the upstream Illumos
version to be compatible with Linux.  Due to the very limited
stack space in the kernel a lz4 workspace kmem cache is used.
Since we are using gcc we are also able to take advantage of the
gcc optimized __builtin_ctz functions.

Support for GRUB has been dropped from this patch.  That code
is available but those changes will need to made to the upstream
GRUB package.

Lastly, several hunks of dead code were dropped for clarity.  They
include the functions real_LZ4_uncompress(), LZ4_compressBound()
and the Visual Studio specific hunks wrapped in _MSC_VER.

Ported-by: Eric Dillmann <eric@jave.fr>
Signed-off-by: Brian Behlendorf <behlendorf1@llnl.gov>
Closes #1217
This commit is contained in:
Eric Dillmann
2013-01-23 10:54:30 +01:00
committed by Brian Behlendorf
parent ff5b1c8065
commit 9759c60f1a
13 changed files with 1188 additions and 2 deletions
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man/man5/zpool-features.5
+34
View File
@@ -1,5 +1,6 @@
'\" te
.\" Copyright (c) 2012 by Delphix. All rights reserved.
.\" Copyright (c) 2013 by Saso Kiselkov. All rights reserved.
.\" The contents of this file are subject to the terms of the Common Development
.\" and Distribution License (the "License"). You may not use this file except
.\" in compliance with the License. You can obtain a copy of the license at
@@ -197,5 +198,38 @@ This feature is \fBactive\fR while there are any filesystems, volumes,
or snapshots which were created after enabling this feature.
.RE
.sp
.ne 2
.na
\fB\fBlz4_compress\fR\fR
.ad
.RS 4n
.TS
l l .
GUID org.illumos:lz4_compress
READ\-ONLY COMPATIBLE no
DEPENDENCIES none
.TE
\fBlz4\fR is a high-performance real-time compression algorithm that
features significantly faster compression and decompression as well as a
higher compression ratio than the older \fBlzjb\fR compression.
Typically, \fBlz4\fR compression is approximately 50% faster on
compressible data and 200% faster on incompressible data than
\fBlzjb\fR. It is also approximately 80% faster on decompression, while
giving approximately 10% better compression ratio.
When the \fBlz4_compress\fR feature is set to \fBenabled\fR, the
administrator can turn on \fBlz4\fR compression on any dataset on the
pool using the \fBzfs\fR(1M) command. Please note that doing so will
immediately activate the \fBlz4_compress\fR feature on the underlying
pool (even before any data is written). Since this feature is not
read-only compatible, this operation will render the pool unimportable
on systems without support for the \fBlz4_compress\fR feature. At the
moment, this operation cannot be reversed. Booting off of
\fBlz4\fR-compressed root pools is supported.
.RE
.SH "SEE ALSO"
\fBzpool\fR(1M)