Using the Summit ssky Condo Partition

Summit has 20 Intel Skylake nodes that were provisioned through contributions by individual research groups. These Skylake “condo” nodes are members of the ssky partition. Condo contributors have preemptive access to their contributed nodes (collectively 15-of-the-20 nodes). All Summit users have access to a general-access pool of ssky nodes (5-of-the-20 nodes contributed by CU and CSU), and preemptable access to all ssky nodes.

Each Skylake node has 24 cores, 174.6 GB of available memory, and employs the AVX-512 instruction set. By comparison the Summit Haswell nodes have 24 cores, 113 GB available memory, and employ the AVX2 instruction set.

Access for condo contributors

Summit condo contributors have access to a summit condo contributor account with the format:

ucb-summit-{group} or csu-summit-{group}

For example if the RC operations group had contributed nodes then their condo account would be: ucb-summit-rcops (note: the rcops group is just used here for the sake of example). You can determine what accounts you are affiliated with using the command:

sacctmgr list associations cluster=summit user=$USER format=Account -p

Contributed condo nodes have been placed into discrete partitions, with a name based on the contributor account name and node type; for example, ssky-ucb-rcops for RC operations contributed Skylake compute nodes. You can see the list of all ssky partitions using the command:

scontrol show partition | grep PartitionName=ssky

To run a job (in this case assuming your group is rcops), specify the account and partition in your job script or interactive job command (e.g., --account=ucb-summit-rcops and --partition=ssky-ucb-rcops).

Jobs run with condo accounts/partitions will immediately preempt jobs running on a given condo partition that were executing via the ssky-preemptable partition (see below).

Tip: If it is appropriate for your jobs, you can use an ordered list of preferred partitions when running your jobs to ssky. E.g., --partition=ssky-ucb-rcops,ssky or (if you are willing to run preemtably) --partition=ssky-ucb-rcops,ssky,ssky-preemptable. If your first choice of partition is not available, the next partition in the list will be attempted, and so on.

General and preemptable access for all Summit users

All Summit users, including condo contributors, can run jobs to either general-access (e.g., ssky) partitions or preemptable (e.g., ssky-preemptable) partitions. Jobs using the ssky partition will not be preempted, but are limited to the five general-access nodes. Jobs using the ssky-preemptable partition may run on any ssky node, but are subject to being preempted by a job from a condo contributor, as described above.

To run a job to ssky, users would simply change the “partition” flag in their job script or interactive job command to either --partition=ssky or --partition=ssky-preemptable. Other flags in their job script would remain the same, though users may want to tweak flags or recompile code (optimized for AVX-512) per the specifications of ssky nodes (see above).

Summary

Partition	Description
ssky-ucb-{group}	Contributor access; preempts ssky-preemptable
ssky	General access
ssky-preemptable	General access; all nodes; preempted by ssky-{ucb,csu}-{group}

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