RPM roadmapping

Peter Jones pjones at redhat.com
Thu Aug 2 17:23:34 UTC 2007

Callum Lerwick wrote:
> On Wed, 2007-08-01 at 16:26 -0400, Bill Nottingham wrote:
>> bz2 makes things somewhat smaller, with a significant increase in
>> cpu time and memory usage; unknown how much that is worth it. rpm
>> already gzips the payload.
> bz2 is orders of magnitude slower than gzip. It tends to be worth it
> with source tarballs, where bz2's compression is especially effective,
> the bandwidth savings outweigh the slowness and you're usually not
> dealing with gigabytes of data.
> Now, installing an entire 4-6-10gb Fedora distro from bz2 will likely
> stretch your install time to days on a mediocre machine, and weeks on a
> slow one. Not worth it.

I don't think you're right.  For package (or whole OS) installation 
we're mostly I/O bound, with some latency added by scriptlets.  Some of 
the scriptlets are cpu bound, but that doesn't matter in this context 
since we're not decompressing things while the scriptlets run.  In the 
package installation scenario, rpm is basically piping the output of the 
decompression into cpio -di .  CPU time isn't really an issue; the 
output is being limited by disk i/o.  You're basically not going to be 
cpu bound unless your target media is *extremely* fast.  If you're in a 
situation where that's the case, you're still going to get a faster 
install than most users, so the decompression isn't really a point of pain.


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