61 lines
2.5 KiB
Diff
61 lines
2.5 KiB
Diff
From 9fb8c7b550cddb6504386a8776e0abaeac4c1f20 Mon Sep 17 00:00:00 2001
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From: "Richard W.M. Jones" <rjones@redhat.com>
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Date: Sat, 14 Jul 2018 21:25:13 +0100
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Subject: [PATCH 02/12] xz: Minor rewrites to improve the flow of the man page.
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---
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plugins/xz/nbdkit-xz-plugin.pod | 26 ++++++++++++++------------
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1 file changed, 14 insertions(+), 12 deletions(-)
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diff --git a/plugins/xz/nbdkit-xz-plugin.pod b/plugins/xz/nbdkit-xz-plugin.pod
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index 75cb881..7d8332a 100644
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--- a/plugins/xz/nbdkit-xz-plugin.pod
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+++ b/plugins/xz/nbdkit-xz-plugin.pod
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@@ -24,29 +24,31 @@ find out how many streams and blocks are in an xz file by doing:
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$ xz --list winxp.img.xz
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Strms Blocks Compressed Uncompressed Ratio Check Filename
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1 1 2,100.0 MiB 6,144.0 MiB 0.342 CRC64 winxp.img.xz
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- =============
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+ ↑↑↑ ↑↑↑
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+ streams blocks
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xz files are seekable on block boundaries only. Seeking is done by
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-seeking directly to the lower block boundary, then (slowly)
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-uncompressing data until the precise byte is reached.
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-
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-B<To get best random access performance, you must prepare your xz
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+seeking directly to the lower block boundary, then uncompressing data
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+until the precise byte is reached. As uncompressing xz data is slow,
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+B<to get best random access performance, you must prepare your xz
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files with many small blocks.>
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-To do this, use the I<--block-size> option with a small-ish block
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-size. For example the same image as above compressed with a 16 MB
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-block size:
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+Use the I<--block-size> option with a small-ish block size. For
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+example this is the same image compressed with a 16 MB block size:
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$ xz --best --block-size=16777216 winxp.img
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+ ─────────────────────
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$ xz --list winxp.img.xz
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Strms Blocks Compressed Uncompressed Ratio Check Filename
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1 384 2,120.1 MiB 6,144.0 MiB 0.345 CRC64 winxp.img.xz
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+ ↑↑↑
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+ blocks
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-This file can be accessed randomly, and at most 16 MB of compressed
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-data will have to be uncompressed to seek to any byte.
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+This file can be accessed randomly. At most 16 MB will have to be
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+uncompressed to seek to any byte.
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-Note as you would expect, xz cannot compress quite as efficiently when
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-using a small block size. The space penalty in the above example is
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+As you would expect, xz cannot compress as efficiently when using a
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+smaller block size. The space penalty in the above example is
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S<E<lt> 1%> of the compressed file size.
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=head1 PARAMETERS
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--
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2.17.1
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