Coprocessor - Auxiliary processor
In the mainframe context, a coprocessor or auxiliary processor is a specialized hardware component designed to perform specific, computationally intensive tasks more efficiently than the general-purpose Central Processor (CP). Its primary role is to offload the CP, improving overall system performance and throughput for specialized workloads by handling dedicated functions.
Key Characteristics
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- Specialized Functionality: Designed for specific tasks such as cryptographic operations (e.g., encryption, decryption, hashing), data compression, or historically, high-speed floating-point arithmetic.
- Hardware Integration: Physically integrated into the mainframe system, often as dedicated cards or modules within the processor complex, like the IBM Crypto Express adapters.
- Offloads General-Purpose Processors: Reduces the workload on the main CPs, allowing them to focus on general application processing and operating system tasks, thereby enhancing system throughput.
- Managed by z/OS: The z/OS operating system manages the allocation and utilization of coprocessors, providing interfaces for applications to access their specialized functions.
- Dedicated Resources: Possesses its own processing logic, memory, and sometimes I/O capabilities, optimized for its specific function, operating independently of the main CPU cycles for the offloaded task.
Use Cases
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- Cryptographic Operations: IBM's Crypto Express coprocessors are widely used for hardware-accelerated encryption/decryption, digital signature generation/verification, and secure key management, critical for data security and compliance (e.g., SSL/TLS, PGP, FIPS 140-2).
- Data Compression/Decompression: Specialized coprocessors can accelerate data compression and decompression for large datasets, improving I/O performance and reducing storage requirements for applications like DB2 or IMS backups.
- Secure Key Management: Cryptographic coprocessors provide a Hardware Security Module (HSM) environment for generating, storing, and managing cryptographic keys securely, preventing their exposure to software vulnerabilities.
- Random Number Generation: Used to generate high-quality, hardware-based random numbers essential for cryptographic protocols and security applications, often required for compliance standards.
Related Concepts
Coprocessors complement the Central Processors (CPs) by handling specialized workloads, allowing CPs to focus on general application execution. They are managed by z/OS, which provides the necessary software interfaces (e.g., Integrated Cryptographic Service Facility (ICSF)) for applications to utilize their capabilities. Applications like CICS, DB2, and IMS can leverage coprocessors for tasks such as data encryption or secure communication, enhancing the overall security and performance of the enterprise computing environment. They are a key component in the mainframe's ability to deliver high-volume, secure transaction processing and maintain data integrity.
- Proper Configuration: Ensure coprocessors are correctly configured and activated in the Hardware Management Console (HMC) and z/OS I/O Configuration Program (IOCP) or Hardware Configuration Definition (HCD).
- API Utilization: Applications should use the appropriate z/OS cryptographic services APIs (e.g., Common Cryptographic Architecture (CCA), PKCS #11) to effectively offload cryptographic operations to the hardware, rather than relying on software-based encryption.
- Monitoring and Capacity Planning: Monitor coprocessor utilization using tools like RMF or SMF to ensure they are not becoming a bottleneck and plan for additional capacity if workloads demand it.
- Security Management: For cryptographic coprocessors, adhere to strict security protocols for key management, access control, and physical security to maintain compliance (e.g., FIPS 140-2).
- Firmware Updates: Regularly apply firmware updates to coprocessors to ensure optimal performance, security, and access to new features, especially in a rapidly evolving security landscape.