Jeff Squyres wrote:
> Here's a thought that I've been kicking around in my head since we re-
> started the PLPA conversation: if we're making an interesting and
> useful API to query internal host topology information, should it
> really be Linux-specific?
>
> The PLPA was originally created to address a problem that was
> specific to Linux (the fact that the API changed 3 times). But our
> recent conversations are addressing a much wider range of issues
> (topology stuff).
>
> More specifically: perhaps PLPA 1.0.x is good exactly as it is. It's
> a small, self-contained library that does one thing and does it
> well. Adding plpa-taskset(1) is a Good evolutionary step, and still
> preserves the idea that PLPA is a small, self-contained thing.
>
> Perhaps the topology functionality should be separated into a
> separate, cross-OS library (Linux, Solaris, Windows [gasp!]) that
> would be genuinely useful for portable software authors (particular
> as core counts are increasing).
Great, now I have no longer an arguing problem why memory and cache
topology information shouldn't be exported by the lib too ;-)
>
> Additionally, the PLPA API is somewhat tailored for Linux. The
> Solaris affinity API, for example, is much richer / more feature-
> full. It may not be useful to try to abstract all the affinity
> functionality into a common library that represents the least common
> denominator. The topology information can be returned in a common
> way without loss of functionality, regardless of the OS's back-end
> mechanism for delivering it.
>
> The PLPA could still *use* libtopo (e.g., so that you can specify
> socket/core tuples to plpa-taskset(1)), but the implementation of the
> topology functionality would be logically separate (i.e., in a
> library that plpa_taskset links against).
Here I remember that I want to ask you, whether the sc_merge() function
from the plpa-taskset code could possible moved as a new function to the
topo api? Or better the whole parsing stuff could be exported by the lib.
And I remember more, that I think I found some little bugs in the
plpa-taskset.c code. I will post the patch as a new mail.
> I admit some self-serving interests here: if we make this be a cross-
> platform API, I can use it directly in Open MPI without needing to
> put in a shim layer to translate between OMPI's internal data
> structures/interface and libtopo, and it would work on multiple
> platforms without needing to write more OMPI code.
>
No problem, I know this fact, and in the end I use OMPI too ;-)
So feel free to create this new project.
Regards
Bert
|
![[Flag]](../../../../../community/mirrors/flag-us.gif){kind=small}