Re: Why we don't use bzip2 in sysinstall/rescue?

On Fri, 17 Aug 2007, Oliver Fromme wrote:

> LI Xin wrote:
> > As a side note.  For networked installation, using bzip2 would reduce
> > traffic by ~11%.
>
> And increase local installation time by 900% (except maybe
> on high-end machines).
>
> I just tested extracting a 10 MB .bz2 file to /dev/null
> on our 800 MHz server:  It took 57 seconds.  Recompressing
> the result to .gz, extracting that took only 5 seconds.
> The installation data is roughly 30 times that much.

I tried this on my 1.8ghz pentium M laptop with 5.6MB of jpg data.

I did:

tar cvf foo.tar foo
cat foo.tar >> /dev/null
time bzip2/gzip foo.tar

I removed and recreated the tar each time.  The cat was to make sure it 
was in cache, although it certainly was from the creation step before.

Anyway, the results are:

bzip2
2.452u 0.026s 0:07.65 32.2% 92+3227k 5+43io 0pf+0w 1849c/6w

gzip
0.539u 0.020s 0:01.75 31.4% 109+3268k 2+44io 0pf+0w 493c/3w

So only 4.6x slower here although my processor is twice as fast.  Still, I 
imagine local installation is actually dominated by transfer rates from 
the cd and file creation time on the new volume.  Making lots of little 
files is relatively slow, and I bet we don't use softupdates on the 
target volume during sysinstall.  A better test would be to actually 
extract a bzip and a gzip from a cd to a local filesystem and 
measure the times.

I wouldn't rule it out just yet.

Thanks,
Jeff

>
> Best regards
>   Oliver
>
> -- 
> Oliver Fromme, secnetix GmbH & Co. KG, Marktplatz 29, 85567 Grafing b. M.
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> "... there are two ways of constructing a software design:  One way
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> the other way is to make it so complicated that there are no _obvious_
> deficiencies."        -- C.A.R. Hoare, ACM Turing Award Lecture, 1980
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