[Yt-dev] Parallel Hop

[Matthew Turk]

Hi Stephen,

Awesome.  I am going to see if I can replicate your methodology over
here sometime this weekend, because this is great stuff and it should
get written up.

Looks like basically the entire analysis workflow is now parallelized
-- derived quantities, projections, halo profiling, radial & phase
plots, I think even slices, and HOP.  The only major component I see
as missing is clump finding, and I have an idea for that, but for now
it should be parallelized on the iterate-over-halos level.

This is tremendous.

-Matt

On Thu, Jan 22, 2009 at 5:26 PM, Stephen Skory <stephenskory at yahoo.com> wrote:
> All,
>
>> Could you quantify that a bit, Stephen?  I definitely agree with the
>> point about the fuzziness of halo boundaries, but how far off are the
>> results when you vary processor count?  If you were to make halo
>> catalogs of the same dataset using 1,2,4,8, etc. processors, and then
>> compare them (assuming that n=1 processor is the "perfect" solution),
>> how far off are the halo centers?
>
> If you're interested, I've made a parameter-space survey of processor counts and padding, here, with lots of pictures:
>
> http://stephenskory.com/research/?p=1469
>
> It's password protected. Contact me off-list if you want it.
>
> But in summary, I found that parallel hop differs from serial by no more than 1% in absolute particle count, and the change is larger in smaller haloes, which are already vague to begin with. Even for very large objects (relative to the box) a little bit of padding goes a long way, 0.05 is nearly identical to a padding of 0.2. However, padding is still required to get good answers. The centers change by very, very little between serial and parallel.
>
>  _______________________________________________________
> sskory at physics.ucsd.edu           o__  Stephen Skory
> http://physics.ucsd.edu/~sskory/ _.>/ _Graduate Student
> ________________________________(_)_\(_)_______________
> _______________________________________________
> Yt-dev mailing list
> Yt-dev at lists.spacepope.org
> http://lists.spacepope.org/listinfo.cgi/yt-dev-spacepope.org
>