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stage2: squashfs blocksize tweaks

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Looks like the 128k default block size is pretty well chosen:
it saves ~6% of image size compared to 64k, and subsequent
differences are ~3% per doubling the block size up to 1M
(thanks led@ for carrying out the tests).

So we'll stick with 256k for "normal" xz compression (inodes
uncompressed) and get 512k back for "tight" one (compressed).
The runtime performance issues are to be examined yet when
bootchart or the like is deployed, nothing drastic though.

With "fast" (gzip/lzo) squash compression inodes go unmolested.

For the record, tight live-webkiosk builds as 95M image in 3:40,
and tight live-flightgear.iso builds as 669M image in 6:34.  Nice.

There's no much sense going for 1M block size: e.g. live-webkiosk
would drop to 93M (3:46) but its load time would increase up to
2:07 as compared to 1:48 for -b 524288 and 1:42 for -b 262144 -noI
on a Duron 500/512M system given the very same DVD+RW media.
This commit is contained in:
Michael Shigorin 2012-04-09 20:03:03 +03:00
parent 931d23e86c
commit 8d16069882
1 changed files with 25 additions and 18 deletions
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43
features.in/stage2/stage1/scripts.d/03-test-kernel
View File

@ -3,9 +3,9 @@
# check relevant kernel features availability
CONFIGS=/boot/config-*
GZ_OPTS="-comp gzip"
XZ_OPTS="-comp xz -b 262144 -noI"
LZO_OPTS="-comp lzo"
GZ_OPTS="-comp gzip -noI"
XZ_OPTS="-comp xz"
LZO_OPTS="-comp lzo -noI"
verbose() { [ -n "$GLOBAL_VERBOSE" ] && echo "** $@" >&2; }
fatal() { echo "** error: $@" >&2; exit 1; }
@ -30,19 +30,26 @@ done
verbose "GLOBAL_SQUASHFS: $GLOBAL_SQUASHFS"
# squashfs options: not really neccessary but better than none
# NB: this config file should be carried over into install2
if [ "$GLOBAL_SQUASHFS" != "fast" ] && configured "SQUASHFS_XZ=y"; then
# NB: the decompression filter overhead might hurt
# NB: there are arm, powerpc and some other filters too
if [ "$GLOBAL_SQUASHFS" = "tight" ] && configured "X86"; then
XZ_OPTS="$XZ_OPTS -Xbcj x86"
options()
{
# squashfs options: not really neccessary but better than none
# NB: this config file should be carried over into install2
if [ "$GLOBAL_SQUASHFS" != "fast" ] && configured "SQUASHFS_XZ=y"; then
# NB: the decompression filter overhead might hurt
# NB: there are arm, powerpc and some other filters too
if [ "$GLOBAL_SQUASHFS" = "tight" ] && configured "X86"; then
XZ_OPTS="$XZ_OPTS -b 524288 -Xbcj x86"
else
XZ_OPTS="$XZ_OPTS -b 262144 -noI"
fi
echo "$XZ_OPTS"
else # go fast, or even faster if possible
if configured "SQUASHFS_LZO=y"; then
echo "$LZO_OPTS"
else # safe default
echo "$GZ_OPTS"
fi
fi
echo "PACK_SQUASHFS_OPTS=$XZ_OPTS"
else # go fast, or even faster if possible
if configured "SQUASHFS_LZO=y"; then
echo "PACK_SQUASHFS_OPTS=$LZO_OPTS"
else # safe default
echo "PACK_SQUASHFS_OPTS=$GZ_OPTS"
fi
fi > /.image/squashcfg.mk
}
echo "PACK_SQUASHFS_OPTS=-no-recovery `options`" > /.image/squashcfg.mk