Using GPUs with Slurm

For general advice on job scheduling, see Running jobs.

Available hardware

These are the GPUs currently available:

# of Nodes	Cluster	Type specifier	CPU cores	CPU memory	GPUs per node	GPU model	Topology
172	Béluga	-	40	191000M	4	V100-SXM2-16GB	All GPUs associated with the same CPU socket, connected via NVLink
114	Cedar	p100	24	128000M	4	P100-PCIE-12GB	Two GPUs per CPU socket
32	Cedar	p100l	24	257000M	4	P100-PCIE-16GB	All GPUs associated with the same CPU socket
192	Cedar	v100l	32	192000M	4	V100-PCIE-32GB	Two GPUs per CPU socket; all GPUs connected via NVLink
160	Graham	p100	32	127518M	2	P100-PCIE-12GB	One GPU per CPU socket
7	Graham	v100	28	183105M	8	V100-PCIE-16GB	See Graham: Volta GPU nodes
30	Graham	t4	44	192000M	4	Tesla T4 16GB	Two GPUs per CPU socket
15	Hélios	k20	20	110000M	8	K20 5GB	Four GPUs per CPU socket
6	Hélios	k80	24	257000M	16	K80 12GB	Eight GPUs per CPU socket
54	Mist	-	32	256GB	4	V100-SXM2-32GB	See Mist specifications

Specifying the type of GPU to use

Some clusters have more than one GPU type available (Cedar, Graham, Hélios), and some clusters only have GPUs on certain nodes (Béluga, Cedar, Graham). You can choose the type of GPU to use by supplying the type specifier to Slurm. The following options are available:

On Béluga

Béluga has only one type of GPU, so no type specification is required.

On Cedar

You can request a 12G P100 using

 #SBATCH --gres=gpu:p100:1

or a 16G P100 using

 #SBATCH --gres=gpu:p100l:4

or a 32G V100 using

 #SBATCH --gres=gpu:v100l:1

If no type is specified, GPU jobs will run on 12G P100s.

On Graham

You can request a P100 using

 #SBATCH --gres=gpu:p100:1

or a V100 using

 #SBATCH --gres=gpu:v100:1

or a T4 using

 #SBATCH --gres=gpu:t4:1

If no type is specified, a GPU job will run on a P100.

On Hélios

You can request a K20 using

 #SBATCH --gres=gpu:k20:1

or a K80 using

 #SBATCH --gres=gpu:k80:1

Mist

Mist is a cluster comprised of IBM Power9 CPUs (not Intel x86!) and NVIDIA V100 GPUs. Users with access to Niagara can also access Mist. To specify job requirements on Mist, please see the specific instructions on the SciNet web site.

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                         # you can use 'nvidia-smi' for a test

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

For each GPU requested on:

• Béluga, we recommend no more than 10 CPU cores.
• Cedar, we recommend no more than 6 CPU cores per P100 GPU (p100 and p100l) and no more than 8 CPU cores per V100 GPU (v100l).
• Graham, we recommend no more than 16 CPU cores.

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 --ntasks=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

Whole nodes

If your application can efficiently use an entire node and its associated GPUs, you will probably experience shorter wait times if you ask Slurm for a whole node. Use one of the following job scripts as a template.

Requesting a GPU node on Graham

File : graham_gpu_node_job.sh

#!/bin/bash
#SBATCH --nodes=1
#SBATCH --gres=gpu:2
#SBATCH --ntasks-per-node=32
#SBATCH --mem=127000M
#SBATCH --time=3:00
#SBATCH --account=def-someuser
nvidia-smi

Requesting a P100 GPU node on Cedar

File : cedar_gpu_node_job.sh

#!/bin/bash
#SBATCH --nodes=1
#SBATCH --gres=gpu:p100:4
#SBATCH --ntasks-per-node=24
#SBATCH --exclusive
#SBATCH --mem=125G
#SBATCH --time=3:00
#SBATCH --account=def-someuser
nvidia-smi

Requesting a P100-16G GPU node on Cedar

There is a special group of GPU nodes on Cedar which have four Tesla P100 16GB cards each. (Other P100 GPUs in the cluster have 12GB and the V100 GPUs have 32G.) The GPUs in a P100L node all use the same PCI switch, so the inter-GPU communication latency is lower, but bandwidth between CPU and GPU is lower than on the regular GPU nodes. The nodes also have 256GB RAM. You may only request these nodes as whole nodes, therefore you must specify --gres=gpu:p100l:4. P100L GPU jobs up to 28 days can be run on Cedar.

File : p100l_gpu_job.sh

#!/bin/bash
#SBATCH --nodes=1 
#SBATCH --gres=gpu:p100l:4   
#SBATCH --ntasks=1
#SBATCH --cpus-per-task=24    # There are 24 CPU cores on P100 Cedar GPU nodes
#SBATCH --mem=0               # Request the full memory of the node
#SBATCH --time=3:00
#SBATCH --account=def-someuser
hostname
nvidia-smi

Packing single-GPU jobs within one SLURM job

If you need to run four single-GPU programs or two 2-GPU programs for longer than 24 hours, GNU Parallel is recommended. A simple example is given below:

cat params.input | parallel -j4 'CUDA_VISIBLE_DEVICES=$(({%} - 1)) python {} &> {#}.out'

In this example the GPU ID is calculated by subtracting 1 from the slot ID {%}. {#} is the job ID, starting from 1.

A params.input file should include input parameters in each line, like this:

code1.py
code2.py
code3.py
code4.py
...

With this method, users can run multiple tasks in one submission. The -j4 parameter means GNU Parallel can run a maximum of four concurrent tasks, launching another as soon as each one ends. CUDA_VISIBLE_DEVICES is used to ensure that two tasks do not try to use the same GPU at the same time.

Message Passing Interface