11.8. Internal frameworks

The Modular Component Architecture (MCA) is the backbone of PMIx – most services and functionality are implemented through MCA components.

Here is a list of all the component frameworks in PMIx as of this writing February-2024:

  • bfrops: Buffer Operations, including support for pack/unpack, copy, print, compare, and load of data types and structured objects

  • gds: Generalized DataStore for storing job-level and other data

  • pcompress: Compress to support compression of large data objects

  • pdl: DLopen support

  • pfexec: Fork/Exec support to allow tools to start child processes

  • pgpu: GPU support

  • pif: Interface discovery

  • pinstalldirs: Install Directories - provides a struct containing all installation locations

  • plog: Logging of user-provided alerts

  • pmdl: Programming Model - provides support for a range of programming models and libraries, including collection of default parameters and environmental variables for forwarding and setting of library-specific environmental variables

  • pnet: Network support, including computation of endpoints to support the instant on launch procedure

  • preg: Regular expression generator and parser

  • prm: Resource Manager support - translation of generic PMIx directives (e.g., mapping and resource definitions) to RM-specific values and general RM-specific support

  • psec: Security operations such as connection handshakes

  • psensor: Sensor framework for monitoring processes, including resource utilization and state-of-health (e.g., heartbeat)

  • psquash: Internal framework for squashing integer data values during transmission

  • pstat: Statistics, including reporting resource usage at the process, node, and disk levels

  • pstrg: Storage system support for querying availability and characteristics of file systems

  • ptl: Transport Layer for client-server and tool-server communication

11.8.1. Framework notes

Each framework typically has one or more components that are used at run-time. For example, the bfrops framework is used by PMIx to pack/unpack data for transmission, copy data objects, and other data manipulation operations. The v3 component, for example, supports the data object definitions introduced in v3 of the library, while the v41 component supports those introduced in v4.1.

11.8.2. MCA parameter notes

Each component typically has some tunable parameters that can be changed at run-time. Use the pmix_info(1) command to check a component to see what its tunable parameters are. For example:

shell$ pmix_info --param psensor file

shows the parameters (and default values) for the file psensor component.

See this section for details on how to set MCA parameters at run time.