***`normal` QoS:** This QoS has no limits and is typically applied to partitions that do not require user or job
***`normal` QoS:** This QoS has no limits and is typically applied to partitions that do not require user or job
restrictions.
***`cpu_general` QoS:** This is the **default QoS** for `merlin7`_users_. It limits the total resources available to each
user. Additionally, this QoS is applied to the `general` partition, enforcing restrictions at the partition level and
@@ -172,17 +165,17 @@ Similarly, if no partition is specified, jobs are automatically submitted to the
partitions provide higher priority and ensure quicker scheduling compared
to **general**, which has limited node availability.
The **`hourly`** partition may include private nodes as an additional buffer. However, the current Slurm partition configuration, governed
by **`PriorityTier`**, ensures that jobs submitted to private partitions are prioritized and processed first. As a result, access to the
The **`hourly`** partition may include private nodes as an additional buffer. However, the current Slurm partition configuration, governed
by **`PriorityTier`**, ensures that jobs submitted to private partitions are prioritized and processed first. As a result, access to the
**`hourly`** partition might experience delays in such scenarios.
The **`interactive`** partition is designed specifically for real-time, interactive work. Here are the key characteristics:
* **CPU Oversubscription:** This partition allows CPU oversubscription (configured as `FORCE:4`), meaning that up to four interactive
* **CPU Oversubscription:** This partition allows CPU oversubscription (configured as `FORCE:4`), meaning that up to four interactive
jobs may share the same physical CPU core. This can impact performance, but enables fast access for short-term tasks.
***Highest Scheduling Priority:** Jobs submitted to the interactive partition are always prioritized. They will be scheduled
***Highest Scheduling Priority:** Jobs submitted to the interactive partition are always prioritized. They will be scheduled
before any jobs in other partitions.
***Intended Use:** This partition is ideal for debugging, testing, compiling, short interactive runs, and other activities where
***Intended Use:** This partition is ideal for debugging, testing, compiling, short interactive runs, and other activities where
immediate access is important.
!!! warning
@@ -223,12 +216,14 @@ For submittng jobs to the GPU cluster, **the cluster name `gmerlin7` must be spe
### GPU general configuration
The **Merlin7 GPU cluster** is configured with the **`CR_CORE_MEMORY`**, **`CR_ONE_TASK_PER_CORE`**, and **`ENFORCE_BINDING_GRES`** options.
* This configuration treats both cores and memory as consumable resources.
* Since the nodes are running with **hyper-threading** enabled, each core thread is counted as a CPU
* Since the nodes are running with **hyper-threading** enabled, each core thread is counted as a CPU
to fulfill a job's resource requirements.
* Slurm will allocate the CPUs to the selected GPU.
By default, Slurm will allocate one task per core, which means:
* For hyper-threaded nodes (NVIDIA A100-based nodes), each task will consume 2 **CPUs**, regardless of whether both threads are actively used by the job.
* For the NVIDIA GraceHopper-based nodes, each task will consume 1 **CPU**.
@@ -247,15 +242,16 @@ scripts accordingly.
Notes on memory configuration:
***Memory allocation options:** To request additional memory, use the following options in your submission script:
* **`--mem=<mem_in_MB>`**: Allocates memory per node.
* **`--mem-per-cpu=<mem_in_MB>`**: Allocates memory per CPU (equivalent to a core thread).
* **`--mem=<mem_in_MB>`**: Allocates memory per node.
* **`--mem-per-cpu=<mem_in_MB>`**: Allocates memory per CPU (equivalent to a core thread).
The total memory requested cannot exceed the **`MaxMemPerNode`** value.
***Impact of disabling Hyper-Threading:** Using the **`--hint=nomultithread`** option disables one thread per core,
* **Impact of disabling Hyper-Threading:** Using the **`--hint=nomultithread`** option disables one thread per core,
effectively halving the number of available CPUs. Consequently, memory allocation will also be halved unless explicitly
adjusted.
For MPI-based jobs, where performance generally improves with single-threaded CPUs, this option is recommended.
For MPI-based jobs, where performance generally improves with single-threaded CPUs, this option is recommended.
In such cases, you should double the **`--mem-per-cpu`** value to account for the reduced number of threads.
!!! tip
@@ -265,20 +261,22 @@ adjusted.
In the `gmerlin7` CPU cluster, we enforce certain limits on jobs and users to ensure fair resource usage and prevent
overuse by a single user or job. These limits aim to balance resource availability while maintaining overall cluster
efficiency. However, applying limits can occasionally impact the cluster’s utilization. For example, user-specific
efficiency. However, applying limits can occasionally impact the cluster’s utilization. For example, user-specific
limits may result in pending jobs even when many nodes are idle due to low activity.
On the other hand, these limits also enhance cluster efficiency by preventing scenarios such as a single job monopolizing
all available resources, which could block other jobs from running. Without job size limits, for instance, a large job
all available resources, which could block other jobs from running. Without job size limits, for instance, a large job
might drain the entire cluster to satisfy its resource request, a situation that is generally undesirable.
Thus, setting appropriate limits is essential to maintain fair resource usage while optimizing cluster efficiency. These
limits should allow for a mix of jobs of varying sizes and types, including single-core and parallel jobs, to coexist
Thus, setting appropriate limits is essential to maintain fair resource usage while optimizing cluster efficiency. These
limits should allow for a mix of jobs of varying sizes and types, including single-core and parallel jobs, to coexist
effectively.
To implement these limits, **we utilize Quality of Service (QoS)**. Different QoS policies are defined and applied
**to specific partitions** in line with the established resource allocation policies. The table below outlines the
To implement these limits, **we utilize Quality of Service (QoS)**. Different QoS policies are defined and applied
**to specific partitions** in line with the established resource allocation policies. The table below outlines the
various QoS definitions applicable to the merlin7 CPU-based cluster. Here:
*`MaxTRES` specifies resource limits per job.
*`MaxTRESPU` specifies resource limits per user.
@@ -292,7 +290,7 @@ various QoS definitions applicable to the merlin7 CPU-based cluster. Here:
keywords: slurm example, template, examples, templates, running jobs, sbatch, single core based jobs, HT, multithread, no-multithread, mpi, openmp, packed jobs, hands-on, array jobs, gpu
last_updated: 24 Mai 2023
summary: "This document shows different template examples for running jobs in the Merlin cluster."
sidebar: merlin7_sidebar
permalink: /merlin7/slurm-examples.html
---
# Slurm Examples
## Single core based job examples
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