Guarded Storage Value Profiling with Hardware Hooks
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Solution Overview
Problem
Current value profiling methods incur significant overhead costs and impact application performance due to deterministic approaches and limited data collection, particularly with the use of profiling hooks and hardware interrupts.
Innovation Solution
The implementation of a software-directed value profiling system utilizing a hardware-based Guarded Storage (GS) facility and memory manager, which generates lightweight guarded load instructions to selectively enable profiling operations, reducing overhead and enhancing runtime control.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If deterministic profiling approaches with profiling hooks and hardware interrupts are used, then comprehensive data collection is achieved, but significant overhead costs and performance degradation occur
Solution Approach 1:
The patent implements selective profiling by enabling guarded mode only for specific memory regions that require monitoring. Instead of profiling all memory accesses deterministically, the system uses a mask to identify only those regions where profiling data should be collected, thereby reducing overall overhead while maintaining measurement precision for critical areas.
Solution Approach 2:
The system employs periodic scavenge cycles where the guarded storage facility is enabled and disabled in cycles. During these periodic cycles, profiling hooks are invoked only when necessary, rather than continuously, which reduces the frequency of overhead operations while still collecting comprehensive data over time.
2Loss of information
If profiling hooks are invoked on every memory access, then complete profiling data is collected, but overhead costs increase significantly
Solution Approach 1:
The patent applies different profiling behaviors to different memory regions by using a mask to designate specific guarded sections. Only memory accesses to regions marked in the mask trigger profiling hooks, while other regions are accessed normally. This local differentiation reduces the total number of hook invocations while ensuring complete data collection for the designated critical regions.
Solution Approach 2:
The guarded storage facility acts as an intermediary layer between memory accesses and profiling hooks. It intercepts load instructions, checks the mask to determine if the accessed region is guarded, and only then invokes the profiling hook. This intermediary mechanism filters out unnecessary hook invocations, reducing computational overhead while maintaining data completeness for guarded regions.
3Adaptability or versatility
If hardware-based guarded storage facility is used to trigger profiling operations, then runtime control and flexibility are improved, but system complexity increases
Solution Approach 1:
The guarded storage facility is designed to serve multiple functions: it enables selective memory region monitoring, supports configurable scavenge cycles, and integrates with existing memory management structures. By making this single hardware component multi-functional, the patent achieves runtime control flexibility without proportionally increasing system complexity.
Data Source
AI summary
A value profiling method, system and computer program product that leverages a guarded storage facility. During code execution, a first instruction is loaded. The first instruction has a first value designating a first region of memory and the first instruction is related to a first section of the code. A determination is made as to whether a guarded mode is enabled at the first region. Responsive to an enabled guarded mode at the first region, a secondary operation is triggered. The secondary operation is in addition to a primary operation of the first instruction. The primary operation is relative to the first region of the memory. The secondary operation causes a profiling of the first section of the code.