Hi Ralph, Thank you for your comment.
I agree with your conclusion that you leave it as it is. As far as I checked, this behavior will also happen when I try to bind-to the objects which are smaller than ncpus-per-proc, ie, l1cache, l2cache and so on. So, if it is easy to know the number of cores included in the objects, it's better to compare the size and ncpu-per-proc, and generate error & suggestion in such a situation. Regards, Tetsuya Mishima > Been tied up the last few days, but I did spend some time thinking about this some more - and I think I'm going to leave the current behavior as-is, adding a check to see if you specify map-by core > along with cpus-per-proc to generate an error in that situation. My reasoning is that map-by core is a very specific directive - you are telling me to map each process to a specific core. If you then > tell me to bind that process to multiple cpus, you are creating an inherent conflict that I don't readily know how to resolve. > > IMO, the best solution is to generate an error and suggest you map-by slot instead. This frees me to bind as many cpus to that allocated slot as you care to specify, and removes the conflict. > > HTH > Ralph > > On Jan 22, 2014, at 9:37 PM, tmish...@jcity.maeda.co.jp wrote: > > > > > > > Thanks for your explanation, Ralph. > > > > But it's really subtle to understand for me ... > > Anyway, I'd like to report what I found through verbose output. > > > > "-map-by core" calls "bind in place" as below: > > [mishima@manage work]$ mpirun -np 4 -hostfile pbs_hosts -report-bindings > > -cpus-per-proc 4 -map-by core -mca rmaps_base_v > > erbose 10 ~/mis/openmpi/demos/myprog > > ... > > [manage.cluster:11362] mca:rmaps: compute bindings for job [8729,1] with > > policy CORE > > [manage.cluster:11362] mca:rmaps: bindings for job [8729,1] - core to core > > [manage.cluster:11362] mca:rmaps: bind in place for job [8729,1] with > > bindings CORE > > ... > > > > On the other hand, "-map-by slot" calls "bind downward" as below: > > [mishima@manage work]$ mpirun -np 4 -hostfile pbs_hosts -report-bindings > > -cpus-per-proc 4 -map-by slot -mca rmaps_base_v > > erbose 10 ~/mis/openmpi/demos/myprog > > ... > > [manage.cluster:12032] mca:rmaps: compute bindings for job [8571,1] with > > policy CORE > > [manage.cluster:12032] mca:rmaps: bind downward for job [8571,1] with > > bindings CORE > > ... > > > > I think your best guess is right and something is wrong with > > bind_in_place function. I have to say the logic of source code > > is so complex that I could not figure it out. > > > > Regards, > > Tetsuya Mishima > > > >> On Jan 22, 2014, at 8:08 PM, tmish...@jcity.maeda.co.jp wrote: > >> > >>> > >>> > >>> Thanks, Ralph. > >>> > >>> I have one more question. I'm sorry to ask you many things ... > >> > >> Not a problem > >> > >>> > >>> Could you tell me the difference between "map-by slot" and "map-by > > core". > >>> From my understanding, slot is the synonym of core. > >> > >> Not really - see below > >> > >>> But those behaviors > >>> using openmpi-1.7.4rc2 with the cpus-per-proc option are quite > > different > >>> as shown below. I tried to browse the source code but I could not make > > it > >>> clear so far. > >>> > >> > >> It is a little subtle, I fear. When you tell us "map-by slot", we assign > > each process to an allocated slot without associating it to any specific > > cpu or core. When we then bind to core (as we do by > >> default), we balance the binding across the sockets to improve > > performance. > >> > >> When you tell us "map-by core", then we directly associate each process > > with a specific core. So when we bind, we bind you to that core. This will > > cause us to fully use all the cores on the first > >> socket before we move to the next. > >> > >> I'm a little puzzled by your output as it appears that cpus-per-proc was > > ignored, so that's something I'd have to look at more carefully. Best guess > > is that we aren't skipping cores to account for > >> the cpus-per-core setting, and thus the procs are being mapped to > > consecutive cores - which wouldn't be very good if we then bound them to > > multiple neighboring cores as they'd fall on top of each > >> other. > >> > >> > >>> Regards, > >>> Tetsuya Mishima > >>> > >>> [ un-managed environment] (node05,06 has 8 cores each) > >>> > >>> [mishima@manage work]$ cat pbs_hosts > >>> node05 > >>> node05 > >>> node05 > >>> node05 > >>> node05 > >>> node05 > >>> node05 > >>> node05 > >>> node06 > >>> node06 > >>> node06 > >>> node06 > >>> node06 > >>> node06 > >>> node06 > >>> node06 > >>> [mishima@manage work]$ mpirun -np 4 -hostfile pbs_hosts > > -report-bindings > >>> -cpus-per-proc 4 -map-by slot ~/mis/openmpi/dem > >>> os/myprog > >>> [node05.cluster:23949] MCW rank 1 bound to socket 1[core 4[hwt 0]], > > socket > >>> 1[core 5[hwt 0]], socket 1[core 6[hwt 0]], so > >>> cket 1[core 7[hwt 0]]: [./././.][B/B/B/B] > >>> [node05.cluster:23949] MCW rank 0 bound to socket 0[core 0[hwt 0]], > > socket > >>> 0[core 1[hwt 0]], socket 0[core 2[hwt 0]], so > >>> cket 0[core 3[hwt 0]]: [B/B/B/B][./././.] > >>> [node06.cluster:22139] MCW rank 3 bound to socket 1[core 4[hwt 0]], > > socket > >>> 1[core 5[hwt 0]], socket 1[core 6[hwt 0]], so > >>> cket 1[core 7[hwt 0]]: [./././.][B/B/B/B] > >>> [node06.cluster:22139] MCW rank 2 bound to socket 0[core 0[hwt 0]], > > socket > >>> 0[core 1[hwt 0]], socket 0[core 2[hwt 0]], so > >>> cket 0[core 3[hwt 0]]: [B/B/B/B][./././.] > >>> Hello world from process 0 of 4 > >>> Hello world from process 1 of 4 > >>> Hello world from process 3 of 4 > >>> Hello world from process 2 of 4 > >>> [mishima@manage work]$ mpirun -np 4 -hostfile pbs_hosts > > -report-bindings > >>> -cpus-per-proc 4 -map-by core ~/mis/openmpi/dem > >>> os/myprog > >>> [node05.cluster:23985] MCW rank 1 bound to socket 0[core 1[hwt 0]]: > >>> [./B/./.][./././.] > >>> [node05.cluster:23985] MCW rank 0 bound to socket 0[core 0[hwt 0]]: > >>> [B/././.][./././.] > >>> [node06.cluster:22175] MCW rank 3 bound to socket 0[core 1[hwt 0]]: > >>> [./B/./.][./././.] > >>> [node06.cluster:22175] MCW rank 2 bound to socket 0[core 0[hwt 0]]: > >>> [B/././.][./././.] > >>> Hello world from process 2 of 4 > >>> Hello world from process 3 of 4 > >>> Hello world from process 0 of 4 > >>> Hello world from process 1 of 4 > >>> > >>> (note) I have the same behavior in the managed environment by Torque > >>> > >>>> Seems like a reasonable, minimal risk request - will do > >>>> > >>>> On Jan 22, 2014, at 4:28 PM, tmish...@jcity.maeda.co.jp wrote: > >>>> > >>>>> > >>>>> Hi Ralph, I want to ask you one more thing about default setting of > >>>>> num_procs > >>>>> when we don't specify the -np option and we set the cpus-per-proc > > > 1. > >>>>> > >>>>> In this case, the round_robin_mapper sets num_procs = num_slots as > >>> below: > >>>>> > >>>>> rmaps_rr.c: > >>>>> 130 if (0 == app->num_procs) { > >>>>> 131 /* set the num_procs to equal the number of slots on > >>> these > >>>>> mapped nodes */ > >>>>> 132 app->num_procs = num_slots; > >>>>> 133 } > >>>>> > >>>>> However, because of cpus_per_rank > 1, this num_procs will be refused > >>> at > >>>>> the > >>>>> line 61 in rmaps_rr_mappers.c as below, unless we switch on the > >>>>> oversubscribe > >>>>> directive. > >>>>> > >>>>> rmaps_rr_mappers.c: > >>>>> 61 if (num_slots < ((int)app->num_procs * > >>>>> orte_rmaps_base.cpus_per_rank)) { > >>>>> 62 if (ORTE_MAPPING_NO_OVERSUBSCRIBE & > >>> ORTE_GET_MAPPING_DIRECTIVE > >>>>> (jdata->map->mapping)) { > >>>>> 63 orte_show_help("help-orte-rmaps-base.txt", > >>>>> "orte-rmaps-base:alloc-error", > >>>>> 64 true, app->num_procs, app->app); > >>>>> 65 return ORTE_ERR_SILENT; > >>>>> 66 } > >>>>> 67 } > >>>>> > >>>>> Therefore, I think the default num_procs should be equal to the > > number > >>> of > >>>>> num_slots divided by cpus/rank: > >>>>> > >>>>> app->num_procs = num_slots / orte_rmaps_base.cpus_per_rank; > >>>>> > >>>>> This would be more convinient for most of people who want to use the > >>>>> -cpus-per-proc option. I already confirmed it worked well. Please > >>> consider > >>>>> to apply this fix to 1.7.4. > >>>>> > >>>>> Regards, > >>>>> Tetsuya Mishima > >>>>> > >>>>> _______________________________________________ > >>>>> users mailing list > >>>>> us...@open-mpi.org > >>>>> http://www.open-mpi.org/mailman/listinfo.cgi/users > >>>> > >>>> _______________________________________________ > >>>> users mailing list > >>>> us...@open-mpi.org > >>>> http://www.open-mpi.org/mailman/listinfo.cgi/users > >>> > >>> _______________________________________________ > >>> users mailing list > >>> us...@open-mpi.org > >>> http://www.open-mpi.org/mailman/listinfo.cgi/users > >> > >> _______________________________________________ > >> users mailing list > >> us...@open-mpi.org > >> http://www.open-mpi.org/mailman/listinfo.cgi/users > > > > _______________________________________________ > > users mailing list > > us...@open-mpi.org > > http://www.open-mpi.org/mailman/listinfo.cgi/users > > _______________________________________________ > users mailing list > us...@open-mpi.org > http://www.open-mpi.org/mailman/listinfo.cgi/users