On Mon, 13 Apr 2015 11:34:29 +0200, Chris Jones <jon...@hep.phy.cam.ac.uk>
wrote:
On 13/04/15 10:27, j. van den hoff wrote:
thanks to both of you for your answers and clarifications.
On Mon, 13 Apr 2015 04:04:14 +0200, Ryan Schmidt
<ryandes...@macports.org> wrote:
On Apr 12, 2015, at 5:54 AM, j. van den hoff wrote:
I just have upgraded two x86_64 machines from 10.9. to 10.10.3 and
upgraded one of them according to the migration guide (i.e.
uninstalled/reinstalled all ~ 800 macports packages). this took an
astonishing long time (over night, basically) partly due to a
multi-hour recompilation of the `atlas' library. and that was on the
faster machine with an SSD...
This is intentional, because atlas is performance-sensitive, so the
port is deliberately programmed to not use precompiled binaries from
our build server, and to instead build on your computer. My
understanding is that the build process builds atlas many times, with
different compiler settings, then tries out each one to see which one
is actually fastest on your particular computer, then installs that
one. That's why it takes so long.
yes, I understand that. I'm not sure, however, how much of a performance
hit I will see when using the intel core-i7 optimized binary on an intel
core 2 duo, so I just would try it out, whether it's OK for my use (that
would mean via `octave', which I am using only sporadically, so ...).
If the core-i7 build is using CPU instructions your core 2 due does not
have, then the performance hit will be 'significant' (i.e. it simply
will not run...).
OK, _that_ I would note and accordingly would recompile ;-). I'm not
trying to avoid that at all costs, anyway. being able to transfer an
existing comprehensive macports installation to further machines seems
valuable in itself I would say, e.g. if you are on a slow internet
connection or just want to quickly get some "canonical" set of software
running on the other machines. at least if such a procedure is not calling
for real trouble (except with atlas, probably).
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