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Message-ID: <469E9180.3050906@zytor.com>
Date: Wed, 18 Jul 2007 15:17:36 -0700
From: "H. Peter Anvin" <hpa@...or.com>
To: Andi Kleen <andi@...stfloor.org>
CC: Matt Mackall <mpm@...enic.com>,
Jonathan Campbell <jon@...dgrounds.com>,
linux-kernel@...r.kernel.org
Subject: Re: Patches for REALLY TINY 386 kernels
Andi Kleen wrote:
>>
>> However, compressed size reductions as an abstract thing is useful for
>> this market. Just not these particular ones. The first thing to get
>> there is probably an LZMA-based compressor instead of gzip.
>
> That would need more memory again.
>
Actually, even with a 64K dictionary size (for which point the
decompression runtime memory requirements are comparable to gzip) LZMA
beats both gzip -9 and bzip2 -9 quite handily:
Reference (this is an i386 kernel):
-rwxrwxr-x 1 hpa hpa 5607558 Jul 18 15:04 vmlinux.bin*
-rw-rw-r-- 1 hpa hpa 2658275 Jul 18 15:04 vmlinux.bin.bz2
-rw-rw-r-- 1 hpa hpa 2760849 Jul 18 15:04 vmlinux.bin.gz
Pure LZMA with dictionary sizes from 2^16 to 2^24:
-rw-rw-r-- 1 hpa hpa 2380983 Jul 18 15:14 d16.7z
-rw-rw-r-- 1 hpa hpa 2317458 Jul 18 15:15 d18.7z
-rw-rw-r-- 1 hpa hpa 2284746 Jul 18 15:15 d20.7z
-rw-rw-r-- 1 hpa hpa 2264001 Jul 18 15:15 d22.7z
-rw-rw-r-- 1 hpa hpa 2263185 Jul 18 15:15 d24.7z
LZMA with BCJ precompression:
-rw-rw-r-- 1 hpa hpa 2236070 Jul 18 15:14 d16bcj.7z
-rw-rw-r-- 1 hpa hpa 2167873 Jul 18 15:15 d18bcj.7z
-rw-rw-r-- 1 hpa hpa 2134541 Jul 18 15:15 d20bcj.7z
-rw-rw-r-- 1 hpa hpa 2112987 Jul 18 15:15 d22bcj.7z
-rw-rw-r-- 1 hpa hpa 2111917 Jul 18 15:15 d24bcj.7z
> Better just write less bloated code. Perhaps mandatory bloatometer
> runs during -rc*s for kernels with minimal config with public code pig shame lists
> similar to the regression lists are useful. Anyone volunteering?
>
> I suspect there is also much more low hanging fruit of this around.
Most likely.
> I don't think eliminating cpuid is a step forward though; that's
> just madness.
Agreed, especially given the invasiveness of the patch.
-hpa
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