Coherent Accelerator Processor Interface (CAPI)

Transform your enterprise and accelerate innovation

In today’s high performance compute environments, acceleration of algorithms is key to meeting end customers’ service requirements. Acceleration can deliver both higher performance and lower cost, but only if the compute platform is designed for heterogeneous computing. The IBM POWER8® chip, with its Coherent Accelerator Processor Interface (CAPI) technology, delivers on this promise of accelerated computing.

What is CAPI?

Whether the workload is on the premises or in the cloud, IT organizations must provide increased system performance as their workloads grow with demands for big data analysis, social media applications, continuous customer connectivity, and business-specific applications. Increases in processor performance alone cannot satisfy the workload demands. Therefore, solutions must also come from system-level advances such as heterogeneous computing, processing engine customization, and open platform development that enables cross-company innovation.

CAPI connects a custom acceleration engine to the coherent fabric of the POWER8 chip. The hybrid solution has a simple programming paradigm while delivering performance well beyond today’s I/O-attached acceleration engines.

With many accelerators now available, solution providers are using CAPI to improve performance versus existing solutions, to lower costs, and to create solutions that were previously beyond the reach of the compute complex.

Traditional Acceleration versus CAPI

CAPI versus traditional acceleration

CAPI on POWER8 systems provides a high-performance solution for the implementation of software-specific, computation-heavy algorithms on an FPGA. This innovation can replace either application programs running on a core or custom acceleration implementations attached via I/O. CAPI removes the overhead and complexity of the I/O subsystem, allowing an accelerator to operate as an extension of an application. The IBM solution enables higher system performance with a much smaller programming investment, allowing heterogeneous computing to be successful across a much broader range of applications.

Because the FPGAs are reconfigured, hardware can be specialized without the traditional costs of hardware fabrication. CAPI enables a customer-defined FPGA solution to be a peer to the POWER8 cores from a memory access (coherent) standpoint.

Features and benefits

Features Benefits
Customizable accelerator Application developers can create an accelerator specifically tailored to their application using an FPGA platform. This specialization can improve performance.
Virtual addressing An accelerator acts as a peer to the POWER8 cores, creating a truly shared memory space between the application and FPGA accelerator. The accelerator essentially becomes another thread of the application. Address translation is managed by the POWER8 processor.
Coherency Application developers use a hardware managed 256KB cache in the FPGA for improved latency and synchronization with the main application threads.
The FPGA cache is fully coherent with the caches in the POWER8 cores.
Simple API Application developers can easily start and control the accelerator.
The API features an intuitive programming interface similar to any multi-threaded application.
Flexible programming model Application developers determine the best programming model for their application. The application can either dispatch work for the accelerator or the accelerator can act independently. This flexibility enables devices such as edge-of-network accelerators to process incoming work independently and to notify the main application when data is ready.
Extendable architecture Application developers can choose an OpenPOWER Foundation partner device, such as Nallatech’s CAPI Developer Kit.
Extendable to other FPGA platforms, the architecture uses card features such as Ethernet and DRAM.
In addition, the architecture supports prepackaged CAPI solutions such as the IBM Data Engine for NoSQL.

CAPI enabled POWER servers

For more information about CAPI-enabled Power Systems, see:

CAPI products

All CAPI products require a POWER8 system with CAPI enabled. The POWER8 processor contains logic that enables a CAPI-attached product to participate in the system-wide memory coherency protocol. API users either develop their own solution or purchase a prepackaged CAPI solution. Check back often to view the growing list of CAPI accelerators. There are two categories of CAPI-related products. Enablement products provide the hardware, software, tools, and infrastructure that lets you to create a CAPI Solution. End solutions are accelerator products that run on your POWER8 servers.

CAPI enablement products

CAPI developer kit

Three OpenPOWER Foundation partner companies now offer the CAPI Developer Kit: Nallatech, Alpha-Data, and Semptian…with more coming. A CAPI developer kit lets you create a custom processing engine that is a peer to the POWER8 cores. The end CAPI solution can be for your own IT use or can be resold as a prepackaged CAPI-App solution.

Before purchasing a CAPI developer kit, read the CAPI Decision Guide and Development Process. This document helps you decide if the CAPI Developer Kit is right for your application. It also describes the resources and skills needed to create a CAPI solution.

Purchase a CAPI developer kit available through OpenPOWER Foundation partners, Nallatech and Alpha-Data

CAPI SNAP framework

The CAPI SNAP Framework (SNAP stands for Storage, Network, and Analytics Programming) delivers enablement and a path to acceleration for application developers via simple API calls and programmable acceleration actions.

CAPI Developer framework

As the CAPI ecosystem grows, IBM and our partners are creating more development tools to assist with the creation of CAPI accelerators. The following frameworks are offered as open source:

CAPI solutions

CAPI solutions refers to a customer application that uses an FPGA-based accelerator on top of the CAPI infrastructure. The accelerator, called by the application, provides performance enhancements, security, or other quality of service enhancements vs. a non-accelerated application. CAPI Solutions are available for purchase from the application vendor or IBM.

Database acceleration and enablement

Storage augmenting accelerators

Financial and insurance accelerators

  • CAPI-Enabled Order Book for high-frequency trading
    Algo-Logic Systems’ Coherent Accelerator Processor Interface (CAPI) enabled Order Book is an FPGA hardware accelerator that processes market data while running on the Nallatech P385 card in an IBM POWER8 server.

CAPI blogs

Connect with the CAPI team

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