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Subject: Re: [hwloc-users] Using hwloc to map GPU layout on system
From: Brock Palen (brockp_at_[hidden])
Date: 2014-02-06 15:31:34


Actually that did turn out to help. The nvml# devices appear to be numbered in the way that CUDA_VISABLE_DEVICES sees them, while the cuda# devices are in the order that PBS and nvidia-smi see them.

      PCIBridge
        PCIBridge
          PCIBridge
            PCI 10de:1021
              CoProc L#2 "cuda0"
              GPU L#3 "nvml2"
          PCIBridge
            PCI 10de:1021
              CoProc L#4 "cuda1"
              GPU L#5 "nvml3"
      PCIBridge
        PCIBridge
          PCIBridge
            PCI 10de:1021
              CoProc L#6 "cuda2"
              GPU L#7 "nvml0"
          PCIBridge
            PCI 10de:1021
              CoProc L#8 "cuda3"
              GPU L#9 "nvml1"

Right now I am trying to create a python script that will take the XML output of lstopo and give me just the cuda and nvml devices in order.

I dont' know if some value are deterministic though. Could I ignore the CoProc line and just use the:

              GPU L#3 "nvml2"
              GPU L#5 "nvml3"
              GPU L#7 "nvml0"
              GPU L#9 "nvml1"

Is the L# always going to be in the oder I would expect? Because then I already have my map then.

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

On Feb 5, 2014, at 1:19 AM, Brice Goglin <Brice.Goglin_at_[hidden]> wrote:

> Hello Brock,
>
> Some people reported the same issue in the past and that's why we added the "nvml" objects. CUDA reorders devices by "performance". Batch-schedulers are somehow supposed to use "nvml" for managing GPUs without actually using them with CUDA directly. And the "nvml" order is the "normal" order.
>
> You need "tdk" (https://developer.nvidia.com/tesla-deployment-kit) to get nvml library and development headers installed. Then hwloc can build its "nvml" backend. Once ready, you'll see a hwloc "cudaX" and a hwloc "nvmlY" object in each NVIDIA PCI devices, and you can get their locality as usual.
>
> Does this help?
>
> Brice
>
>
>
> Le 05/02/2014 05:25, Brock Palen a écrit :
>> 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
>>
>>
>>
>>
>>
>>
>> _______________________________________________
>> hwloc-users mailing list
>>
>> hwloc-users_at_[hidden]
>> http://www.open-mpi.org/mailman/listinfo.cgi/hwloc-users
>
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