On Aug 29, 2011, at 8:35 AM, nadia.der...@bull.net wrote: > > devel-boun...@open-mpi.org wrote on 08/29/2011 04:20:30 PM: > > > De : Ralph Castain <r...@open-mpi.org> > > A : Open MPI Developers <de...@open-mpi.org> > > Date : 08/29/2011 04:26 PM > > Objet : Re: [OMPI devel] known limitation or bug in hwloc? > > Envoyé par : devel-boun...@open-mpi.org > > > > Actually, I'll eat those words. I was looking at the wrong place. > > > > Yes, that is a bug in hwloc. It needs to loop over CPU_MAX for those > > cases where the bit mask extends over multiple words. > > But I'm afraid the fix won't be trivial at all: hwloc in itself is coherent: > it loops overs NUM_BITS, but it uses masks that are NUM_BITS wide > (hwloc_bitmap_t set)...
I guess I'm missing that - I just did a search and cannot find any reference to OPAL_PAFFINITY_BITMASK_T_NUM_BITS anywhere in paffinity/hwloc after the last change. Can you point me to where you believe a problem exists? Or feel free to submit a patch to fix it :-) We can push it upstream to the hwloc folks for their consideration. > > Regards, > Nadia > > > > > > On Aug 29, 2011, at 7:16 AM, Ralph Castain wrote: > > > > > Actually, if you look closely at the definition of those two > > values, you'll see that it really doesn't matter which one we loop > > over. The NUM_BITS value defines the actual total number of bits in > > the mask. The CPU_MAX is the total number of cpus we can support, > > which was set to a value such that the two are equal (i.e., it's a > > power of two that happens to be an integer multiple of 64). > > > > > > I believe the original intent was to allow CPU_MAX to be > > independent of address-alignment questions, so NUM_BITS could > > technically be greater than CPU_MAX. Even if this happens, though, > > all that would do is cause the loop to run across more bits than required. > > > > > > So it doesn't introduce a limitation at all. In hindsight, we > > could simplify things by eliminating one of those values and just > > putting a requirement on the number that it be a multiple of 64 so > > it aligns with a memory address. > > > > > > > > > On Aug 29, 2011, at 7:05 AM, Kenneth Lloyd wrote: > > > > > >> Nadia, > > >> > > >> Interesting. I haven't tried pushing this to levels above 8 on a > > >> particular > > >> machine. Do you think that the cpuset / paffinity / hwloc only applies at > > >> the machine level, at which time you need to employ a graph with carto? > > >> > > >> Regards, > > >> > > >> Ken > > >> > > >> -----Original Message----- > > >> From: devel-boun...@open-mpi.org [mailto:devel-boun...@open-mpi.org] On > > >> Behalf Of nadia.derbey > > >> Sent: Monday, August 29, 2011 5:45 AM > > >> To: Open MPI Developers > > >> Subject: [OMPI devel] known limitation or bug in hwloc? > > >> > > >> Hi list, > > >> > > >> I'm hitting a limitation with paffinity/hwloc with cpu numbers >= 64. > > >> > > >> In opal/mca/paffinity/hwloc/paffinity_hwloc_module.c, module_set() is > > >> the routine that sets the calling process affinity to the mask given as > > >> parameter. Note that "mask" is a opal_paffinity_base_cpu_set_t (so we > > >> allow the cpus to be potentially numbered up to > > >> OPAL_PAFFINITY_BITMASK_CPU_MAX - 1). > > >> > > >> The problem with module_set() is that is loops over > > >> OPAL_PAFFINITY_BITMASK_T_NUM_BITS bits to check if these bits are set in > > >> the mask: > > >> > > >> for (i = 0; ((unsigned int) i) < OPAL_PAFFINITY_BITMASK_T_NUM_BITS; ++i) > > >> { > > >> if (OPAL_PAFFINITY_CPU_ISSET(i, mask)) { > > >> hwloc_bitmap_set(set, i); > > >> } > > >> } > > >> > > >> Given "mask"'s type, I think module_set() should instead loop over > > >> OPAL_PAFFINITY_BITMASK_CPU_MAX bits. > > >> > > >> Note that module_set() uses a type for its internal mask that is > > >> coherent with OPAL_PAFFINITY_BITMASK_T_NUM_BITS (hwloc_bitmap_t). > > >> > > >> So I'm wondering whether this is a known limitation I've never heard of > > >> or an actual bug? > > >> > > >> Regards, > > >> Nadia > > >> > > >> > > >> _______________________________________________ > > >> devel mailing list > > >> de...@open-mpi.org > > >> http://www.open-mpi.org/mailman/listinfo.cgi/devel > > >> ----- > > >> No virus found in this message. > > >> Checked by AVG - www.avg.com > > >> Version: 10.0.1392 / Virus Database: 1520/3864 - Release Date: 08/28/11 > > >> > > >> _______________________________________________ > > >> devel mailing list > > >> de...@open-mpi.org > > >> http://www.open-mpi.org/mailman/listinfo.cgi/devel > > > > > > > > > _______________________________________________ > > devel mailing list > > de...@open-mpi.org > > http://www.open-mpi.org/mailman/listinfo.cgi/devel > _______________________________________________ > devel mailing list > de...@open-mpi.org > http://www.open-mpi.org/mailman/listinfo.cgi/devel
