From 6365f1af886d21b5b5038328f2ec28474e6eef16 Mon Sep 17 00:00:00 2001 From: Mikael Simberg Date: Fri, 4 Apr 2025 10:25:06 +0200 Subject: [PATCH 1/2] Minor updates to GB low noise mode description --- docs/guides/gb2025.md | 12 ++++++++---- 1 file changed, 8 insertions(+), 4 deletions(-) diff --git a/docs/guides/gb2025.md b/docs/guides/gb2025.md index 403e9987..d61d899a 100644 --- a/docs/guides/gb2025.md +++ b/docs/guides/gb2025.md @@ -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 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: @@ -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 ``` From 9fc7a59d7e7612048df1867dbeef291c15edea1c Mon Sep 17 00:00:00 2001 From: Mikael Simberg Date: Fri, 4 Apr 2025 11:46:44 +0200 Subject: [PATCH 2/2] Update docs/guides/gb2025.md --- docs/guides/gb2025.md | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) diff --git a/docs/guides/gb2025.md b/docs/guides/gb2025.md index d61d899a..b42403ce 100644 --- a/docs/guides/gb2025.md +++ b/docs/guides/gb2025.md @@ -55,7 +55,7 @@ Your data sets from Daint are available on Santis 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 that SLURM job scripts must be updated to account for the reserved cores. +This means that SLURM job scripts must be updated to account for the reserved cores. ### SLURM