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Subject: [hwloc-users] Using hwloc to map GPU layout on system
From: Brock Palen (brockp_at_[hidden])
Date: 2014-02-04 23:25:14


We are trying to build a system to mask users to the GPU's they were assigned by our batch system (torque).

The batch system sets the GPU's into thread exclusive mode when assigned to a job, so we want the GPU that the batch system assigns to be the one set in CUDA_VISIBLE_DEVICES,

Problem is on our nodes what the batch system sees as gpu 0 is not the same GPU that CUDA_VISIBLE_DEVICES sees as 0. Actually 0 is 2.

You can see this behavior is you run

nvidia-smi and look at the PCI ID's of the devices. You can then look at the PCI ID's outputed by deviceQuery from the SDK examples and see they are in a different order.

The ID's you would set in CUDA_VISIBLE_DEVICES matches the order that deviceQuery sees, not the order that nvida-smi sees.

Example (All values turned to decimal to match deviceQuery):

nvidia-smi order: 9, 10, 13, 14, 40, 43, 48, 51
dviceQuery order: 13, 14, 9, 10, 40, 43, 48, 51

Can hwloc help me with this? Right now I am hacking a script based on the output of the two commands, and making a map, between the two and then set CUDA_VISIBLE_DEVICES

Any ideas would be great. Later as we currently also use CPU sets, we want to pass GPU locality information to the scheduler to make decisions to match GPU-> CPU Socket information, as performance of threads across QPI domains is very poor.

Thanks

Machine (64GB)
  NUMANode L#0 (P#0 32GB)
    Socket L#0 + L3 L#0 (20MB)
      L2 L#0 (256KB) + L1d L#0 (32KB) + L1i L#0 (32KB) + Core L#0 + PU L#0 (P#0)
      L2 L#1 (256KB) + L1d L#1 (32KB) + L1i L#1 (32KB) + Core L#1 + PU L#1 (P#1)
      L2 L#2 (256KB) + L1d L#2 (32KB) + L1i L#2 (32KB) + Core L#2 + PU L#2 (P#2)
      L2 L#3 (256KB) + L1d L#3 (32KB) + L1i L#3 (32KB) + Core L#3 + PU L#3 (P#3)
      L2 L#4 (256KB) + L1d L#4 (32KB) + L1i L#4 (32KB) + Core L#4 + PU L#4 (P#4)
      L2 L#5 (256KB) + L1d L#5 (32KB) + L1i L#5 (32KB) + Core L#5 + PU L#5 (P#5)
      L2 L#6 (256KB) + L1d L#6 (32KB) + L1i L#6 (32KB) + Core L#6 + PU L#6 (P#6)
      L2 L#7 (256KB) + L1d L#7 (32KB) + L1i L#7 (32KB) + Core L#7 + PU L#7 (P#7)
    HostBridge L#0
      PCIBridge
        PCI 1000:0087
          Block L#0 "sda"
          Block L#1 "sdb"
      PCIBridge
        PCIBridge
          PCIBridge
            PCI 10de:1021
              CoProc L#2 "cuda0"
          PCIBridge
            PCI 10de:1021
              CoProc L#3 "cuda1"
      PCIBridge
        PCIBridge
          PCIBridge
            PCI 10de:1021
              CoProc L#4 "cuda2"
          PCIBridge
            PCI 10de:1021
              CoProc L#5 "cuda3"
      PCIBridge
        PCI 8086:1521
          Net L#6 "eth0"
        PCI 8086:1521
          Net L#7 "eth1"
      PCIBridge
        PCI 102b:0533
      PCI 8086:1d02
  NUMANode L#1 (P#1 32GB)
    Socket L#1 + L3 L#1 (20MB)
      L2 L#8 (256KB) + L1d L#8 (32KB) + L1i L#8 (32KB) + Core L#8 + PU L#8 (P#8)
      L2 L#9 (256KB) + L1d L#9 (32KB) + L1i L#9 (32KB) + Core L#9 + PU L#9 (P#9)
      L2 L#10 (256KB) + L1d L#10 (32KB) + L1i L#10 (32KB) + Core L#10 + PU L#10 (P#10)
      L2 L#11 (256KB) + L1d L#11 (32KB) + L1i L#11 (32KB) + Core L#11 + PU L#11 (P#11)
      L2 L#12 (256KB) + L1d L#12 (32KB) + L1i L#12 (32KB) + Core L#12 + PU L#12 (P#12)
      L2 L#13 (256KB) + L1d L#13 (32KB) + L1i L#13 (32KB) + Core L#13 + PU L#13 (P#13)
      L2 L#14 (256KB) + L1d L#14 (32KB) + L1i L#14 (32KB) + Core L#14 + PU L#14 (P#14)
      L2 L#15 (256KB) + L1d L#15 (32KB) + L1i L#15 (32KB) + Core L#15 + PU L#15 (P#15)
    HostBridge L#12
      PCIBridge
        PCIBridge
          PCIBridge
            PCI 15b3:1003
              Net L#8 "eth2"
              Net L#9 "ib0"
              Net L#10 "eoib0"
              OpenFabrics L#11 "mlx4_0"
      PCIBridge
        PCIBridge
          PCIBridge
            PCI 10de:1021
              CoProc L#12 "cuda4"
          PCIBridge
            PCI 10de:1021
              CoProc L#13 "cuda5"
      PCIBridge
        PCIBridge
          PCIBridge
            PCI 10de:1021
              CoProc L#14 "cuda6"
          PCIBridge
            PCI 10de:1021
              CoProc L#15 "cuda7"

Brock Palen
www.umich.edu/~brockp
CAEN Advanced Computing
XSEDE Campus Champion
brockp_at_[hidden]
(734)936-1985