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Subject: Re: [OMPI users] Running OpenMPI on SGI Altix with 4096 cores : very poor performance
From: George Bosilca (bosilca_at_[hidden])
Date: 2010-12-20 14:39:16


Are your processes places the same way with the two MPI implementations? Per-node vs. per-core ?

  george.

On Dec 20, 2010, at 11:14 , Gilbert Grosdidier wrote:

> Bonjour,
>
> I am now at a loss with my running of OpenMPI (namely 1.4.3)
> on a SGI Altix cluster with 2048 or 4096 cores, running over Infiniband.
>
> After fixing several rather obvious failures with Ralph, Jeff and John help,
> I am now facing the bottom of this story since :
> - there are no more obvious failures with messages
> - compared to the running of the application with SGI-MPT, the CPU performances I get
> are very low, decreasing when the number of cores increases (cf below)
> - these performances are highly reproducible
> - I tried a very high number of -mca parameters, to no avail
>
> If I take as a reference the MPT CPU speed performance,
> it is of about 900 (in some arbitrary unit), whatever the
> number of cores I used (up to 8192).
>
> But, when running with OMPI, I get:
> - 700 with 1024 cores (which is already rather low)
> - 300 with 2048 cores
> - 60 with 4096 cores.
>
> The computing loop, over which the above CPU performance is evaluated, includes
> a stack of MPI exchanges [per core : 8 x (MPI_Isend + MPI_Irecv) + MPI_Waitall]
>
> The application is of the 'domain partition' type,
> and the performances, together with the memory footprint,
> are very identical on all cores. The memory footprint is twice higher in
> the OMPI case (1.5GB/core) than in the MPT case (0.7GB/core).
>
> What could be wrong with all these, please ?
>
> I provided (in attachment) the 'ompi_info -all ' output.
> The config.log is in attachment as well.
> I compiled OMPI with icc. I checked numa and affinity are OK.
>
> I use the following command to run my OMPI app:
> "mpiexec -mca btl_openib_rdma_pipeline_send_length 65536\
> -mca btl_openib_rdma_pipeline_frag_size 65536\
> -mca btl_openib_min_rdma_pipeline_size 65536\
> -mca btl_self_rdma_pipeline_send_length 262144\
> -mca btl_self_rdma_pipeline_frag_size 262144\
> -mca plm_rsh_num_concurrent 4096 -mca mpi_paffinity_alone 1\
> -mca mpi_leave_pinned 1 -mca btl_sm_max_send_size 128\
> -mca coll_tuned_pre_allocate_memory_comm_size_limit 128\
> -mca btl_openib_cq_size 128 -mca btl_ofud_rd_num 128\
> -mca mpool_rdma_rcache_size_limit 131072 -mca mpi_preconnect_mpi 0\
> -mca mpool_sm_min_size 131072 -mca mpi_abort_print_stack 1\
> -mca btl sm,openib,self -mca btl_openib_want_fork_support 0\
> -mca opal_set_max_sys_limits 1 -mca osc_pt2pt_no_locks 1\
> -mca osc_rdma_no_locks 1\
> $PBS_JOBDIR/phmc_tm_p2.$PBS_JOBID -v -f $Jinput".
>
> OpenIB info:
>
> 1) OFED-1.4.1, installed by SGI SGI
>
> 2) Linux xxxxxx 2.6.16.60-0.42.10-smp #1 SMP Tue Apr 27 05:11:27 UTC 2010 x86_64 x86_64 x86_64 GNU/Linux
> OS : SGI ProPack 6SP5 for Linux, Build 605r1.sles10-0909302200
>
> 3) Running most probably an SGI subnet manager
>
> 4) > ibv_devinfo (on a worker node)
> hca_id: mlx4_0
> fw_ver: 2.7.000
> node_guid: 0030:48ff:ffcc:4c44
> sys_image_guid: 0030:48ff:ffcc:4c47
> vendor_id: 0x02c9
> vendor_part_id: 26418
> hw_ver: 0xA0
> board_id: SM_2071000001000
> phys_port_cnt: 2
> port: 1
> state: PORT_ACTIVE (4)
> max_mtu: 2048 (4)
> active_mtu: 2048 (4)
> sm_lid: 1
> port_lid: 6009
> port_lmc: 0x00
>
> port: 2
> state: PORT_ACTIVE (4)
> max_mtu: 2048 (4)
> active_mtu: 2048 (4)
> sm_lid: 1
> port_lid: 6010
> port_lmc: 0x00
>
> 5) > ifconfig -a (on a worker node)
> eth0 Link encap:Ethernet HWaddr 00:30:48:CE:73:30
> inet adr:192.168.159.10 Bcast:192.168.159.255 Masque:255.255.255.0
> adr inet6: fe80::230:48ff:fece:7330/64 Scope:Lien
> UP BROADCAST NOTRAILERS RUNNING MULTICAST MTU:1500 Metric:1
> RX packets:32337499 errors:0 dropped:0 overruns:0 frame:0
> TX packets:34733462 errors:0 dropped:0 overruns:0 carrier:0
> collisions:0 lg file transmission:1000
> RX bytes:11486224753 (10954.1 Mb) TX bytes:16450996864 (15688.8 Mb)
> Mémoire:fbc60000-fbc80000
>
> eth1 Link encap:Ethernet HWaddr 00:30:48:CE:73:31
> BROADCAST MULTICAST MTU:1500 Metric:1
> RX packets:0 errors:0 dropped:0 overruns:0 frame:0
> TX packets:0 errors:0 dropped:0 overruns:0 carrier:0
> collisions:0 lg file transmission:1000
> RX bytes:0 (0.0 b) TX bytes:0 (0.0 b)
> Mémoire:fbce0000-fbd00000
>
> ib0 Link encap:UNSPEC HWaddr 80-00-00-48-FE-C0-00-00-00-00-00-00-00-00-00-00
> inet adr:10.148.9.198 Bcast:10.148.255.255 Masque:255.255.0.0
> adr inet6: fe80::230:48ff:ffcc:4c45/64 Scope:Lien
> UP BROADCAST RUNNING MULTICAST MTU:65520 Metric:1
> RX packets:115055101 errors:0 dropped:0 overruns:0 frame:0
> TX packets:5390843 errors:0 dropped:182 overruns:0 carrier:0
> collisions:0 lg file transmission:256
> RX bytes:49592870352 (47295.4 Mb) TX bytes:43566897620 (41548.6 Mb)
>
> ib1 Link encap:UNSPEC HWaddr 80-00-00-49-FE-C0-00-00-00-00-00-00-00-00-00-00
> inet adr:10.149.9.198 Bcast:10.149.255.255 Masque:255.255.0.0
> adr inet6: fe80::230:48ff:ffcc:4c46/64 Scope:Lien
> UP BROADCAST RUNNING MULTICAST MTU:65520 Metric:1
> RX packets:673448 errors:0 dropped:0 overruns:0 frame:0
> TX packets:187 errors:0 dropped:5 overruns:0 carrier:0
> collisions:0 lg file transmission:256
> RX bytes:37713088 (35.9 Mb) TX bytes:11228 (10.9 Kb)
>
> lo Link encap:Boucle locale
> inet adr:127.0.0.1 Masque:255.0.0.0
> adr inet6: ::1/128 Scope:Hôte
> UP LOOPBACK RUNNING MTU:16436 Metric:1
> RX packets:33504149 errors:0 dropped:0 overruns:0 frame:0
> TX packets:33504149 errors:0 dropped:0 overruns:0 carrier:0
> collisions:0 lg file transmission:0
> RX bytes:5100850397 (4864.5 Mb) TX bytes:5100850397 (4864.5 Mb)
>
> sit0 Link encap:IPv6-dans-IPv4
> NOARP MTU:1480 Metric:1
> RX packets:0 errors:0 dropped:0 overruns:0 frame:0
> TX packets:0 errors:0 dropped:0 overruns:0 carrier:0
> collisions:0 lg file transmission:0
> RX bytes:0 (0.0 b) TX bytes:0 (0.0 b)
>
> 6) > limit (on a worker node)
> cputime unlimited
> filesize unlimited
> datasize unlimited
> stacksize 300000 kbytes
> coredumpsize 0 kbytes
> memoryuse unlimited
> vmemoryuse unlimited
> descriptors 16384
> memorylocked unlimited
> maxproc 303104
>
> If some info is still missing despite all my efforts, please ask.
>
> Thanks in advance for any hints, Best, G.
>
>
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