LRC (Linguistic Research Cluster) is the name of ÚFAL's computational grid/cluster. The cluster is built on top of SLURM and is using Lustre for data storage.

Currently there are following partitions (queues) available for computing:

In order to submit a job you need to login to one of the head nodes:

 lrc1.ufal.hide.ms.mff.cuni.cz
 lrc2.ufal.hide.ms.mff.cuni.cz

The core idea is that you write a batch script containing the commands you wish to run as well as a list of SBATCH directives specifying the resources or parameters that you need for your job.
Then the script is submitted to the cluster with:

sbatch myJobScript.sh

Here is a simple working example:

#!/bin/bash
#SBATCH -J helloWorld					  # name of job
#SBATCH -p cpu-troja					  # name of partition or queue (if not specified default partition is used)
#SBATCH -o helloWorld.out				  # name of output file for this submission script
#SBATCH -e helloWorld.err				  # name of error file for this submission script

# run my job (some executable)
sleep 5
echo "Hello I am running on cluster!"

After submitting this simple code you should end up with the two files (helloWorld.out and helloWorld.err) in the directory where you called the sbatch command.

Here is the list of other useful SBATCH directives:

#SBATCH -D /some/path/                        # change directory before executing the job   
#SBATCH -N 2                                  # number of nodes (default 1)
#SBATCH --nodelist=node1,node2...             # required node, or comma separated list of required nodes
#SBATCH --cpus-per-task=4                     # number of cores/threads per task (default 1)
#SBATCH --gres=gpu:1                          # number of GPUs to request (default 0)
#SBATCH --mem=10G                             # request 10 gigabytes memory (per node, default depends on node)

If you need you can have slurm report to you:

#SBATCH --mail-type=begin        # send email when job begins
#SBATCH --mail-type=end          # send email when job ends
#SBATCH --mail-type=fail         # send email if job fails
#SBATCH --mail-user=<YourUFALEmailAccount>

As usuall the complete set of options can be found by typing:

man sbatch

In order to inspect all running jobs on the cluster use:

squeue

filter only jobs of user linguist:

squeue -u linguist

filter only jobs on partition gpu-ms:

squeue -p gpu-ms

filter jobs in specific state (see man squeue for list of valid job states):

squeue -t RUNNING

filter jobs running on a specific node:

squeue -w dll-3gpu1

The command sinfo can give you useful information about nodes available in the cluster. Here is a short list of some examples:

List available partitions(queues). The default partition is marked with *:

sinfo

List detailed info about nodes:

sinfo -l -N

List nodes with some custom format info:

sinfo -N -o "%N %P %.11T %.15f"

The minimal computing resource in SLURM is one CPU core. However, CPU count advertised by SLURM corresponds to the number of CPU threads.
If you ask for 1 CPU core with

--cpus-per-task=1

SLURM will allocate all threads of 1 CPU core.

For example dll-8gpu1 will allocate 2 threads since its ThreadsPerCore=2:

$> scontrol show node dll-8gpu1
$ scontrol show node dll-8gpu1
NodeName=dll-8gpu1 Arch=x86_64 CoresPerSocket=16 
   CPUAlloc=0 CPUTot=64 CPULoad=0.05                                               // CPUAlloc - allocated threads, CPUTot - total threads
   AvailableFeatures=gpuram24G
   ActiveFeatures=gpuram24G
   Gres=gpu:nvidia_a30:8(S:0-1)
   NodeAddr=10.10.24.63 NodeHostName=dll-8gpu1 Version=21.08.8-2
   OS=Linux 5.15.35-1-pve #1 SMP PVE 5.15.35-3 (Wed, 11 May 2022 07:57:51 +0200) 
   RealMemory=515838 AllocMem=0 FreeMem=507650 Sockets=2 Boards=1
   CoreSpecCount=1 CPUSpecList=62-63                                               // CoreSpecCount - cores reserved for OS, CPUSpecList - list of threads reserved for system
   State=IDLE ThreadsPerCore=2 TmpDisk=0 Weight=1 Owner=N/A MCS_label=N/A          // ThreadsPerCore - count of threads for 1 CPU core
   Partitions=gpu-ms 
   BootTime=2022-09-01T14:07:50 SlurmdStartTime=2022-09-02T13:54:05
   LastBusyTime=2022-10-02T20:17:09
   CfgTRES=cpu=64,mem=515838M,billing=64
   AllocTRES=
   CapWatts=n/a
   CurrentWatts=0 AveWatts=0
   ExtSensorsJoules=n/s ExtSensorsWatts=0 ExtSensorsTemp=n/s

In the example above you can see comments at all lines relevant to CPU allocation.

This mode can be useful for testing You should be using batch mode for any serious computation.
You can use srun command to get an interactive shell on an arbitrary node from the default partition (queue):

srun --pty bash

There are many more parameters available to use. For example:

srun -p cpu-troja --mem=64G --pty bash

• -p cpu-troja explicitly requires partition cpu-troja. If not specified slurm will use default partition.
• –mem=64G requires 64G of memory for the job

srun -p gpu-troja,gpu-ms --nodelist=tdll-3gpu1 --mem=64G --gres=gpu:2 --pty bash

• -p gpu-troja,gpu-ms require only nodes from these two partitions
• –nodelist=tdll-3gpu1 explicitly requires one specific node
• –gres=gpu:2 requires 2 GPUs

srun -p gpu-troja --constraint="gpuram44G|gpuram39G" --mem=64G --gres=gpu:2 --pty bash

• –constraint=“gpuram44G|gpuram39G” only consider nodes that have either gpuram44G or gpuram39G feature defined

To see all the available options type:

man srun