post install very slooow

[Adam Williamson]

On Fri, 2012-11-09 at 16:30 -0800, Chuck Forsberg WA7KGX N2469R wrote:
> Somehow Anaconda managed to mess up the partition
> table on a different disk, so I had to reinstall a Fedora 16
> to get Windows et al back.
> 
> I noticed the post install processing in f16 lasted only
> a few seconds, not the seemingly interminable wait
> a Fedora 18 install takes.
> 
> Is this some sort of regression?

Yes, though it's smaller than is immediately obvious.

I found a bit of spare time last week and benchmarked this. F17 and
earlier actually paused for rather a long time while still showing
'Package XXX/XXX' - so they were really in post-installation before they
got around to telling you about it. F18 doesn't do this, installation of
the last package goes as quickly as it ought to, and it then immediately
tells you it's in post-install. So if you just count the amount of time
the UI is actually _telling_ you it's in post-install, you over-estimate
the slowness of F18. You have to adjust for the fact that F17 and
earlier lied. :)

When you do so, though, it still turns out that F18 post-install is
slower, just not so much slower.

I compared minimal installs of F17 and F18 - this was before the
firewalld-related growth in the size of F18's minimal package set, so
they were pretty comparable - and these are the numbers I got:

f17, start to finish: 1:23
f18, start to finish: 1:42

f17, last package to complete: 34s
f18, last package to complete: 56s

the 'last package to complete' number is the 'true' post-install time,
counting from when it starts installing the last package till when
install is complete, and accounting for the effect noted above. (the
splits are that f17 spends 30 seconds 'installing the last package' and
just 4 seconds on post-install, while F18 spends just 4 seconds
_actually_ installing the last package and 52 seconds on post-install).
So f18's true post-install time appears to be 22s longer than f17's,
when installing a minimal package set, and this accounts for the entire
overall decrease in f18's 'install performance' - f18 is actually faster
at the stuff before post-install than f17 was.

I mentioned this in #anaconda and interest was shown, but then more
important things came up and we've left it alone since then.

If someone has time to dive deeper into why post-install is taking more
time, though, I'm sure anaconda team would welcome it.
-- 
Adam Williamson
Fedora QA Community Monkey
IRC: adamw | Twitter: AdamW_Fedora | identi.ca: adamwfedora
http://www.happyassassin.net