Skip to content

Minor updates to GB low noise mode description #77

New issue

Have a question about this project? Sign up for a free GitHub account to open an issue and contact its maintainers and the community.

Sign up for GitHub

By clicking “Sign up for GitHub”, you agree to our terms of service and privacy statement. We’ll occasionally send you account related emails.

Already on GitHub? Sign in to your account

Merged
merged 2 commits into from
Apr 4, 2025
Merged

Minor updates to GB low noise mode description #77

Changes from all commits
Commits
Show all changes
2 commits
Select commit Hold shift + click to select a range
6365f1a
Minor updates to GB low noise mode description
msimberg Apr 4, 2025
9fc7a59
Update docs/guides/gb2025.md
msimberg Apr 4, 2025
File filter

Filter by extension

Filter by extension
Conversations
Failed to load comments.
Loading
Jump to
Jump to file
Failed to load files.
Loading
Diff view
Diff view
12 changes: 8 additions & 4 deletions docs/guides/gb2025.md
View file
Open in desktop
Original file line number Diff line number Diff line change
Expand Up @@ -50,7 +50,14 @@ Your data sets from Daint are available on Santis
## Low Noise Mode

!!! note
Low noise mode has been disabled, so the previous requirement that you set `OMP_PLACES` and `OMP_PROC_BIND` no longer applies.
Low noise mode has been relaxed, so the previous requirement that you set `OMP_PLACES` and `OMP_PROC_BIND` no longer applies.
One core per module is still reserved for system processes.

Santis uses low noise mode, which reserves one core per Grace-Hopper module (i.e. per 72 cores) for system processes.
This mode is intended to reduce performance variability caused by system processes interfering with application threads and processes.
This means that SLURM job scripts must be updated to account for the reserved cores.

### SLURM

!!! warning "Unable to allocate resources: Requested node configuration is not available"
If you try to use all 72 cores on each socket, SLURM will give a hard error, because only 71 are available:
Expand All @@ -61,10 +68,7 @@ Your data sets from Daint are available on Santis
srun: error: Unable to allocate resources: Requested node configuration is not available
```

### SLURM

Explicitly set the number of cores per task using the `--cpus-per-task/-c` flag, e.g.:
For example:
```
#SBATCH --cpus-per-task=64
```
Expand Down