[Numpy-discussion] custom atlas

Charles R Harris charlesr.harris at gmail.com
Tue Jul 5 10:37:01 EDT 2011


On Tue, Jul 5, 2011 at 8:13 AM, Neal Becker <ndbecker2 at gmail.com> wrote:

> Charles R Harris wrote:
>
> > On Tue, Jul 5, 2011 at 7:45 AM, Neal Becker <ndbecker2 at gmail.com> wrote:
> >
> >> I thought I'd try to speed up numpy on my fedora system by rebuilding
> the
> >> atlas
> >> package so it would be tuned for my machine.  But when I do:
> >>
> >> rpmbuild -ba -D 'enable_native_atlas 1' atlas.spec
> >>
> >> it fails with:
> >>
> >> res/zgemvN_5000_100 : VARIATION EXCEEDS TOLERENCE, RERUN WITH HIGHER
> REPS.
> >>
> >> A bit of googling has not revealed a solution.  Any hints?
> >>
> >>
> >>
> > I've never seen that, OTOH, I haven't built ATLAS in the last few years.
> Do
> > you have all the power saving/frequency changing options turned off? What
> > version of ATLAS are you using? What CPU?
> >
> > Chuck
>
> Ah, hadn't tried turing off cpuspeed.  Try again... nope same error.
>
> 2 cpus, each:
> model name      : Intel(R) Core(TM)2 Duo CPU     T7500  @ 2.20GHz
> stepping        : 11
> cpu MHz         : 800.000  << that's what it says @idle
>

You haven't got cpu frequency scaling under control. Linux? Depending on the
distro you can write to a file in /sys (for each cpu) or run a program to
make the setting, or click on a panel applet. Sometimes the scaling is set
in the bios also. Google is your friend here. I have

$charris at f13 ~$ cat /sys/devices/system/cpu/cpu0/cpufreq/scaling_governor
ondemand

And what you want to see is performance instead of ondemand.

Chuck
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