Using GPUs with Slurm

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This is not a complete article: This is a draft, a work in progress that is intended to be published into an article, which may or may not be ready for inclusion in the main wiki. It should not necessarily be considered factual or authoritative.

Available hardware

These are the node types containing GPUs currently available on Cedar and Graham:

# of Nodes	Node type	CPU cores	CPU memory	# of GPUs	GPU type	PCIe bus topology
114	Cedar Base GPU	24	128GB	4	NVIDIA P100-PCIE-12GB	Two GPUs per CPU socket
32	Cedar Large GPU	24	256GB	4	NVIDIA P100-PCIE-16GB	All GPUs under same CPU socket
160	Graham Base GPU	32	128GB	2	NVIDIA P100-PCIE-12GB	One GPU per CPU socket

Single-core job

If you need only a single CPU core and one GPU:

File : gpu_serial_job.sh

#!/bin/bash
#SBATCH --account=def-someuser
#SBATCH --gres=gpu:1              # Number of GPUs (per node)
#SBATCH --mem=4000M               # memory (per node)
#SBATCH --time=0-03:00            # time (DD-HH:MM)
./program

Multi-threaded job

For GPU jobs asking for multiple CPUs in a single node:

File : gpu_threaded_job.sh

#!/bin/bash
#SBATCH --account=def-someuser
#SBATCH --gres=gpu:1              # Number of GPU(s) per node
#SBATCH --cpus-per-task=6         # CPU cores/threads
#SBATCH --mem=4000M               # memory per node
#SBATCH --time=0-03:00            # time (DD-HH:MM)
export OMP_NUM_THREADS=$SLURM_CPUS_PER_TASK
./program

On Cedar, we recommend that multi-threaded jobs use no more than 6 CPU cores for each GPU requested. On Graham, we recommend no more than 16 CPU cores for each GPU.

MPI job

File : gpu_mpi_job.sh

#!/bin/bash
#SBATCH --account=def-someuser
#SBATCH --gres=gpu:4              # Number of GPUs per node
#SBATCH --nodes=2                 # Number of nodes
#SBATCH --ntask=48                # Number of MPI process
#SBATCH --cpus-per-task=1         # CPU cores per MPI process
#SBATCH --mem=120G                # memory per node
#SBATCH --time=0-03:00            # time (DD-HH:MM)
export OMP_NUM_THREADS=$SLURM_CPUS_PER_TASK
srun ./program

Using Cedar's Large GPU nodes

The large-memory GPU nodes at Cedar have four Tesla P100 16GB cards each. These GPUs all use the same PCI switch so the inter-GPU communication latency is lower, but bandwidth is also lower than on the regular GPU nodes. The nodes also have 256 GB RAM instead of 128GB. In order to use these nodes you must request all four GPUs, that is, the whole node, and you must specify lgpu, as shown in this example:

File : large_gpu_job.sh

#!/bin/bash
#SBATCH --nodes=1 
#SBATCH --ntasks=1
#SBATCH --cpus-per-task=24    # There are 24 CPU cores on Cedar GPU nodes
#SBATCH --gres=gpu:lgpu:4     # Ask for 4 GPUs per node of the large-gpu node variety
#SBATCH --time=0-00:10 
hostname
nvidia-smi

Message Passing Interface