Messages in this thread | | | Date | Mon, 20 Oct 2003 06:28:37 +0200 | From | Willy Tarreau <> | Subject | Re: Where's the bzip2 compressed linux-kernel patch? |
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On Sun, Oct 19, 2003 at 07:00:47PM -0500, Rob Landley wrote: > upx is upx-1.22. > > So you're talking about something that compresses LESS well than gzip. Why?
I'm not talking about something that compresses LESS than gzip, I'm talking about something I almost always use to recompress my kernels and reduce their size by 20% over gzip, and decompress way faster.
It's upx-1.90 (which is able to decompress/recompress bzimage). OK it's still a development version, but it has already saved me megs of flash.
I don't know how the tests above were done. But what I know for sure is that there are excessive open source zealots who would only download the OSS version of UPX which uses the UCL library while the closed source version uses the NRV one which is a jewel.
And you know what ? when I put a complete distro on a 8MB flash, my primary concern is to save as much space as possible, and my ability to read the compressor sources only comes next.
BTW, I don't remember every upx argument, but I'm sure I got best numbers with '--best --crp-ms=100000'.
> And no, gzip -9 does not add anything to decompression time, only > compression time.
Where did you get this interesting idea ? every decompressor needs decompression time. You need the compressed kernel to be in memory, then you decompress it, then you boot it. On my old 386sx which was still my home firewall 6 months ago, the kernel would take 2-3 seconds to decompress with gzip while it was almost unnoticeable with upx (which did it in place, BTW).
Now don't get me wrong, I'm not advertising for upx. But bzip2 was proposed and will always be criticized because of its decompression time and cost in terms of memory. So I simply suggested to take a look at other solutions which seem interesting. An UPX-based implementation seems interesting to me only if the decompression code is free and can be put in the kernel. Otherwise it is not. If the numbers above come from the UCL lib, then we at least know that this one doesn't interest us for this matter. Some people would also suggest taking a look at other compression algorithms which can be of interest, but I don't know their sources status (open/close).
> I can make bunzip work in-place if you'd like
That's very important for low-memory systems.
Regards, Willy
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