Changing package compression from gzip to LZMA (txz)
Hello
Slackware switched to using LZMA to compress packages in order to solve space issues on the CDs. Since this isn't an issue for ARM, and coupled with my understanding (from xz(1)) that there would be issues decompressing content on machines with limited RAM (128MB, 256MB), it made no sense to change. However, I'm not sure if there really are issues decompressing LZMA packed packages on machines with small amounts of RAM, so I am thinking of changing the compression. I would assume that the decompression would definitley be slower, however. Can any of you with real hardware (there's no point testing QEMU - it's not representative of real hardware speed) that 128 or 256MB RAM test these assumptions and provide some timing info please? Thanks |
I downloadad the kernel source package from slackware x86 (it's one of the beefy packages).
Firs I timed how lon it takes to do a "tar tf": Code:
real 0m50.771s Code:
bash-4.2# time installpkg kernel-source-3.10.17_smp-noarch-3.txz Code:
bash-4.2# free |
I have installed gcc-4.8.2-arm-1.tgz on a raspberrypi with 256mb ram and gpu_mem set at 32mb. Install was off an external usb drive which is where I have my /Slackware directory when I actually install slackware arm on an sd card in a pi. Pi access was via ssh. I installed your tgz packaged first then used makepkg to create a txz package to install.
Code:
root@shed-2:/mnt/sda1# ROOT=/tmp/build time installpkg gcc-4.8.2-arm-1.tgz Code:
root@shed-2:/mnt/sda1# ROOT=/tmp/build time installpkg gcc-4.8.2-arm-1.txz I can do some more testing maybe this evening or tomorrow if you want me to do something specific. Code:
11.95user 5.10system 0:20.08elapsed 84%CPU (0avgtext+0avgdata 6256maxresident)k |
Hi guys
Thanks for that feedback. It's not far off what I was expecting really, and it's good to see that swap wasn't impacted. I'll slowly start changing the package compression to LZMA then as the packages are updated. |
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I know there is a limit on RAM required to decompress a package compress with xz. This depends on the options used to compress it, see xz man page. The default -6 level requires 9 MiB when decompressing, while -9 requires 65 MiB.
As for CPU usage, it is definitely higher than with gzip. |
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I don't think that the kernel would free up 9 Mb when there are 90 Mb free out of 128 and there is not much running on my nas that would require memory anyway. And BTW: Slackware for the Intel platform has been using xz package compression for quite some tine now so I guess that Stuart wants to make the official ARM port more standard exactly by using the standard Slackware package compression algorithm. |
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