On Mar 13, 2014, at 4:59 AM, Mike Dubman <[email protected]> wrote:
> >>>Right? If so, I don't see why you need the AC_TRY_RUN -- if RDMACM is
> >>>easily detectable as to which way it is compiled (because it has, for
> >>>example, different fields), then AC_CHECK_DECLS should be enough, right?
>
> RDMACM API has different implementation requirements for its providers: tcp,
> af_ib (different structs/fields should be used/passed. different APIs/hooks
> should be called for bring-up).
Yes, this was said before. Which is why I don't understand why AC_CHECK_DECLS
isn't enough -- it's a compile-time check, right?
Let me get this straight:
1. AF_IB may or may not be present.
2. If AF_IB is present, it may or may not work (i.e., support for AF_IB may or
may not work in the kernel).
3. If AF_IB is present, you can only compile with the AF_IB fields and methods.
4. If AF_IB is not present, you can only compile with the non-AF_IB fields and
methods.
I think #2 is not relevant for configure -- only #1, #3, and #4 are relevant.
So you should have code something like this:
#if HAVE_DECL_AF_IB
ret = do_the_stuff_with_af_ib(...);
if (OMPI_SUCCESS != ret) {
opal_show_help(...AF_IB doesn't work...);
return ret;
}
#else
ret = do_the_stuff_without_af_ib(...);
if (OMPI_SUCCESS != ret) {
opal_show_help(...non-AF_IB doesn't work...);
return ret;
}
#endif
To be clear: whether AF_IB works or not is a determination to make on the
machines on which you *run* -- NOT on the machine on which you *build*.
This is one of the key reasons that OMPI prefers run-time detection for
run-time characteristics over configure-time detection for run-time
characteristics (because you may run OMPI on different machines than where you
built OMPI).
> Currently, the RDMACM provider can be selected at compile time only and
> mpirun becomes incompatible to other RDMACM providers.
What does mpirun have to do with this? We're talking about the openib BTL,
right?
> AC_TRY_RUN is a protection that selected provider will be able to
> run,otherwise no fallback to other provider will be available for user at
> runtime.
I can't parse this statement...?
--
Jeff Squyres
[email protected]
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