Accelerator Access Control via Credit Revocation
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Solution Overview
Problem
Existing computing systems lack the ability to effectively revoke access to accelerators, limiting system features such as dynamic reconfiguration, live partition, and virtual machine migration without the ability to remove accelerator resources.
Innovation Solution
A credit system is implemented to control access to accelerators, where credits are used to manage access requests, and effective addresses are unmapped upon request to revoke access, ensuring that applications can no longer access the accelerators.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If accelerator resources are allocated to applications, then application performance is improved, but system adaptability deteriorates because accelerator resources cannot be removed for dynamic reconfiguration, live partition migration, or virtual machine migration
Solution Approach 1:
A Virtual Accelerator Switchboard (VAS) is introduced as an intermediary layer between applications and accelerator resources. The VAS manages credit-based access control, allowing accelerators to be allocated to applications when credits are available while enabling systematic revocation of access through credit removal. This intermediary structure supports both application performance and system adaptability by providing controlled access that can be dynamically adjusted for migration and reconfiguration operations.
2Reliability
If accelerator access is maintained continuously, then application functionality is preserved, but system feature capabilities deteriorate because features like live update and dynamic reconfiguration cannot be implemented
Solution Approach 1:
The system implements dynamic accelerator access control through a credit mechanism where access permissions can be adjusted in real-time. Applications maintain accelerator access through allocated credits, but the system can dynamically revoke access by removing credits when system features like live update or dynamic reconfiguration are needed. This dynamic control structure allows the system to switch between maintaining application functionality and enabling system feature capabilities as needed.
3Adaptability or versatility
If a credit system is implemented to control accelerator access, then access revocation capability is improved, but device complexity increases due to the need for credit management, effective address unmapping, and buffer operations
Solution Approach 1:
The credit system divides accelerator access control into discrete, manageable units called credits. Each credit represents a specific access permission, and the Virtual Accelerator Switchboard manages individual credit allocation and revocation independently. This segmentation allows for granular control of accelerator access without requiring complex monolithic control structures. Credits can be individually mapped to effective addresses and revoked through systematic unmapping operations, simplifying the overall control mechanism while maintaining robust access revocation capability.
Data Source
AI summary
Accelerator access control whereby an application's access to an accelerator is revoked in order to allow the system to perform a system function. In one or more embodiments, when an application is executing, a credit system is utilized to provide credits for controlled access to the accelerator. When request information is received to remove access to a credit associated with the application's access to the accelerator, the credit is marked to fail with operating system interfaces. Also, in one or more embodiments, if the credit is in use for accessing the accelerator, an effective address associated with the credit is unmapped from the accelerator.