Boot speedup with readahead

Behdad Esfahbod behdad at behdad.org
Mon Sep 15 17:02:26 UTC 2008


Seth Vidal wrote:
> On Mon, 2008-09-15 at 02:14 -0400, Behdad Esfahbod wrote:
>> Callum Lerwick wrote:
>>> The diversity of RPM front ends is a sign we're doing things right.
>> And the fact that none reliably works...
> 
> Do you think that might reflect on the complexity of problem more than
> it reflects the tools?

I'm sure it is a very very complex problem.  I also hear that a lot of these
problems are caused by RPM having to retain a lot of baggage for the name of
compatibility.  Hence my conclusion.

The question is: if one could throw RPM away and design a new one, could one
do significantly better?  From what I hear I think the answer might be yes.
What does it mean to Fedora:  we need to kick RPM in the butt to catch up with
competition.

Lets look back at the problem at hand: we all agree that custom-installed
glob-matched post-transaction triggers are useful things.  I think I can also
say that we agree that it should be in the lowest-level package management
system.  What has been up to debate so far is whether that lowest-level is
RPM, or that RPM is a lost case and yum is considered the lowest-level.  The
answer to that one does not matter.  A few data points that put this
discussion in perspective however:

  - Michael K Johnson, the very first Fedora Project leader, thought he can
invent a better RPM, left Red Hat, and built Conary.  It does use Python
indeed, and it does support glob-matched scripts.

  - First Mandriva and then SuSE felt they needed to heavily customize RPM and
went down that road.  I wonder how longer we need to wait to reach for the
same conclusion.

  - Kristian Høgsberg built razor which can solve deps in fraction of a second
where yum simply takes way too long.  Is anyone in the RPM camp impressed?
No.  They just don't think it's possible to do with RPM.

  - RPM already supports %posttrans scripts which are a huge improvement over
%post, but when I desperately needed them to refresh fontconfig caches upon
upgrade (using %post the old package is still installed when the script is
run; ouch!), but was told to not use %posttrans as it's broken and eats
babies.  I'm not sure if that's accurate, but that was the recommendation I
got from very core Fedora developers.  This is the kind of limitation RPM
imposes right now.

Now I understand that using RPM is one of Fedora's biggest assets ("industry
standard" blah blah), so I'm not suggesting that we should move to something
significantly different.  Just to acknowledge that there is a problem here,
identify solutions, and fix them.

I'd love to be corrected if any of the above statements is wrong.

behdad

> -sv




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