LSF Job Step Manager

IBM® Job Step Manager (JSM) Version 10.4 is a lightweight job step scheduler that can help you manage available compute resources that are provided through an LSF® allocation.

You can use JSM to run multiple parallel applications. A scenario where JSM might be helpful, is in a testing environment or when you have an application that is run in multiple phases and each phase has its own resource requirements. The granular control that JSM provides is extended to the individual cores, GPUs, and memory of the nodes within the LSF allocation (including the process binding and integration with OpenMP).

JSM is different from IBM® Spectrum Load Sharing Facility (LSF) because it manages a collection of resources for a single user. JSM provides the following features and benefits when compared to LSF:

Job launching

Job steps are created whenever a user attempts to create processes that are running on the allocation. The jsrun command is used to create processes. The jsrun command requests resources and specifics one or more tasks to be launched on those resources. Up to 100,000 job steps can be created within a single LSF allocation.

You can also create new processes by using the PMIx_Spawn API. The PMIx_Spawn API is invoked by calls from the MPI_Comm_spawn API that is used in most MPI implementations.

The jsrun command is designed to provide fast job startup at a large scale by using efficient communication topology and by using the PMIx APIs to provide information to the application that allows the application to quickly connect to peer applications. The jsrun command provides the following features:

You can use the jskill command to signal or terminate launched processes. You can use the jslist command to list job steps that are running, completed, or in a queue. The jsinfo command provides information about the current JSM allocation resources.

PMIx services

PMIx is open source software that establishes a portable API that allows processes to interact with resource managers. The PMIx software provides processes and tasks for requesting the following information services:

To access the features of PMIx, tasks must be registered as PMIx clients. Some MPI implementations use PMIx to launch and manage processes, including IBM Spectrum™ MPI. JSM uses the PMIx version 2.0 convenience library and supports only 2.0 version-based clients. For documentation about PMIx, see the PMIx website.