59 lines
1.7 KiB
Diff
59 lines
1.7 KiB
Diff
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From 986b12d391b8de6c820da1af9bfdb4153c340370 Mon Sep 17 00:00:00 2001
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From: Kairui Song <kasong@redhat.com>
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Date: Wed, 25 Jul 2018 16:47:37 +0800
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Subject: [PATCH] lsinitrd: optimize performance when handling multiple files
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Currently, when trying to unpack or print the content of multiple
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files, lsinitrd will decompress the image and pipe the decompressed
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content to cpio to retrive each file if the image is compressed.
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Which mean if we want to extract 10 files the image will be decompressed
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10 times, which is a waste of time.
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This patch will let lsinitrd decompress the image file to a temp file
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first if multiple file names are given, then cpio will read from the
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decompressed temp file, which will speed up a lot.
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Time consumption test for command:
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`lsinitrd initramfs-4.16.15-300.fc28.x86_64.img \
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usr/lib/dracut/build-parameter.txt \
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usr/lib/dracut/modules.txt \
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etc/machine-id \
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etc/hostname \
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usr/lib/udev/rules.d/99-systemd.rules`
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Before the patch:
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2.37user 0.33system 0:02.12elapsed
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After the patch:
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0.50user 0.42system 0:00.72elapsed
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There would be a more significant time difference if we try to
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extract more files.
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---
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lsinitrd.sh | 11 +++++++++++
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1 file changed, 11 insertions(+)
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diff --git a/lsinitrd.sh b/lsinitrd.sh
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index 1b9a93b6..0cb89e9c 100755
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--- a/lsinitrd.sh
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+++ b/lsinitrd.sh
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@@ -251,6 +251,17 @@ if [[ $SKIP ]]; then
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CAT=skipcpio
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fi
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+if (( ${#filenames[@]} > 1 )); then
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+ TMPFILE="$(mktemp -t --suffix=.cpio lsinitrd.XXXXXX)"
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+ $CAT "$image" 2>/dev/null > $TMPFILE
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+ trap "rm -f '$TMPFILE'" EXIT
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+ pre_decompress()
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+ {
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+ cat $TMPFILE
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+ }
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+ CAT=pre_decompress
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+fi
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+
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ret=0
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if [[ -n "$unpack" ]]; then
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