[Beowulf] [AMD64] Gentoo or Fedora

Greg Lindahl lindahl at pbm.com
Sun Oct 7 15:10:30 PDT 2007

Sorry that this is a "late hit" on this topic, but every time someone
mentions Gentoo, I have to count to 100,000 before I say anything.

>From what I can tell, the dependency stuff in Gentoo mostly works. If
you try to not update any packages unless they have a security issue,
you will discover a steady trickle of things that don't work: packages
that block themselves, for example. Or you (allegedly) have to update
gcc/binutils/the kitchen sink in order to update tar. Or packages that
won't rebuild because they really did need a newer gcc, but it wasn't
in their dependencies. And so forth.

Only by updating all the time will you stick with the herd, and then
things mostly work.

At this very moment I'm having to emerge a ton of stuff on a server
because openssl was updated for security reasons. Hm, elm doesn't compile
anymore, I wonder if anyone will notice if I just delete it?

This kind of thing just doesn't happen with Red Hat or SUSE.

The whole "you can build with compiler flags for your cpu so your
system will be faster thing" doesn't ring true, either. First off,
most computational clusters don't spend a ton of time executing code
that's part of the system. They spend time executing your user code.
Second, compiling the whole system with -O3 --ultra-fast-flags is just
asking for bugs. Do you think that gcc is tested with -O3
--ultra-fast-flags, building itself and all of its test suites? Well,
actually, no. Most gcc testing is done with the flags that Red Hat and
SUSE with the default flags that they build their distros with. The
rest is just luck. And with 100,000,000 lines of code, you'll find
weird bugs popping up in the oddest places, if you looked hard enough.

And this isn't a special flaw of gcc, you won't find anyone anywhere
on the planet building their system with any compiler with its super
optimization flags turned on.

So: Benefit? None. Cost? Dependency nightmares, plus bug risk.

Friends don't let friends use Gentoo on clusters. Or production

-- greg

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