Portals is a low-level network API for high-performance networking on

high-performance computing High-performance computing (HPC) uses supercomputers and computer clusters to solve advanced computation problems. Overview HPC integrates systems administration (including network and security knowledge) and parallel programming into a mult ...

systems developed by

Sandia National Laboratories Sandia National Laboratories (SNL), also known as Sandia, is one of three research and development laboratories of the United States Department of Energy's National Nuclear Security Administration (NNSA). Headquartered in Kirtland Air Force Bas ...

and the

University of New Mexico The University of New Mexico (UNM; es, Universidad de Nuevo México) is a public research university in Albuquerque, New Mexico. Founded in 1889, it is the state's flagship academic institution and the largest by enrollment, with over 25,400 ...

. Portals is currently the lowest-level network programming interface on the commercially successful XT line of supercomputers from

Cray Cray Inc., a subsidiary of Hewlett Packard Enterprise, is an American supercomputer manufacturer headquartered in Seattle, Washington. It also manufactures systems for data storage and analytics. Several Cray supercomputer systems are listed i ...

Overview

Portals is based on the concept of elementary building blocks that can be combined to support a wide variety of upper-level network transport semantics. Portals provides one-sided data movement operations, but unlike other one-sided programming interfaces, the target of a remote operation is not a virtual address. Instead, the ultimate destination in memory of an incoming message is determined at the receiver by comparing contents of the message header with the contents of structures at the destination. This flexibility allows for efficient implementations of both one-sided and two-sided communications. In particular, Portals is aimed at providing the fundamental operations necessary to support a high-performance and scalable implementation of the Message Passing Interface (MPI) standard. It was also used as the initial network transport layer for the Lustre file system.

Early years

Portals began in the early 1990s as an extension to the nX message passing system used in the SUNMOS and Puma operating system. It was first implemented for the

Intel Paragon The Intel Paragon is a discontinued series of massively parallel supercomputers that was produced by Intel in the 1990s. The Paragon XP/S is a productized version of the experimental ''Touchstone Delta'' system that was built at Caltech, launched ...

at Sandia, and later ported to the Intel TeraFLOPS machine named

ASCI Red ASCI Red (also known as ASCI Option Red or TFLOPS) was the first computer built under the Accelerated Strategic Computing Initiative (ASCI), the supercomputing initiative of the United States government created to help the maintenance of the ...

. There were four building blocks in the first version of Portals: the single block, the dynamic block, the independent block and the combined block. All incoming messages would first pass through a match-list that allowed individual portals to respond to specific groups, ranks, and a set of user specified match-bits.

Portals 3

The Portals concept continued to evolve over successive generations of lightweight kernels and massively parallel systems. In 1999, an operational programming interface was given to Portals so that it could be implemented for intelligent or programmable network interfaces outside of a lightweight kernel environment. This standard was designed for systems where the work required to prepare, transmit, and deliver messages is longer than the round-trip to the Portals data structures. For example, in modern systems, this work is dominated by the round-trip through the IO bus to the network interface. The standard has been revised since the initial release to make it more suited for modern high performance, massively parallel computers. The MPI library was ported from the

retronym A retronym is a newer name for an existing thing that helps differentiate the original form/version from a more recent one. It is thus a word or phrase created to avoid confusion between older and newer types, whereas previously (before there were ...

ed Portals 2 to the new Portals 3.0. The Portals 3 specification has been implemented several times, first on

, then on CPlant over

Myrinet Myrinet, ANSI/VITA 26-1998, is a high-speed local area networking system designed by the company Myricom to be used as an interconnect between multiple machines to form computer clusters. Description Myrinet was promoted as having lower protocol ...

Linux Linux ( or ) is a family of open-source Unix-like operating systems based on the Linux kernel, an operating system kernel first released on September 17, 1991, by Linus Torvalds. Linux is typically packaged as a Linux distribution, whi ...

and the Cray XT family.

Portals 4

In light of emerging

partitioned global address space In computer science, partitioned global address space (PGAS) is a parallel programming model paradigm. PGAS is typified by communication operations involving a global memory address space abstraction that is logically partitioned, where a portio ...

(PGAS) languages, several new features have been added to the Portals API as part of Portals 4. Portals 4 also made several changes to improve the interaction between the processor and network interface (NIC) for implementations that provide offload. Finally, an option to support a form of flow-control was added to Portals 4. Portals 4 is the low-level networking API for the Bull-Atos BXI NIC.

External links

Portals Home Page

References

{{reflist Application programming interfaces Parallel computing