Supplementary Micro-Op Cache Allocation for Front-End Stall Relief
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Solution Overview
Problem
The challenge of efficiently providing micro-operations to execution resources in modern processors is exacerbated by the increasing size and complexity of execution pipelines, which are sensitive to front end stalls and face difficulties in growing micro-op caches due to timing, power, and area limitations.
Innovation Solution
Implementing a supplementary cache mechanism that opportunistically uses existing caches, such as instruction or data caches, to store decoded micro-operations, dynamically managing their availability based on performance metrics to enhance micro-op communication and execution efficiency.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If traditional micro-op caches are used to store decoded micro-operations, then decoding costs are reduced through caching, but the cache size growth is limited by timing, power, and area constraints
Solution Approach 1:
The patent makes other caches (instruction cache, data cache) available to receive and store micro-operations in addition to their primary functions. This multi-functional approach allows the micro-op cache to effectively utilize existing cache resources rather than requiring dedicated cache space, thereby improving decoding efficiency without proportionally increasing cache area.
Solution Approach 2:
The system dynamically allocates and reallocates cache resources based on performance metrics and utilization conditions. Cache resources are selectively provisioned to micro-operation storage based on runtime conditions, allowing the system to adapt to varying workload demands and optimize the balance between decoding efficiency and resource utilization.
2Productivity
If micro-op cache size is increased to reduce front-end stalls, then execution pipeline performance improves, but power consumption and timing constraints are violated
Solution Approach 1:
By allowing other caches to serve dual purposes (their original function plus micro-operation storage), the system achieves improved execution pipeline throughput without the need to build larger dedicated micro-op caches, thereby avoiding the associated power consumption increases.
Solution Approach 2:
The system changes the operational parameters of existing caches by dynamically adjusting their allocation and utilization based on performance metrics. This allows the caches to adapt their function and capacity for micro-operation storage based on runtime conditions, optimizing power efficiency while maintaining execution throughput.
3Quantity of substance
If dedicated micro-op cache resources are provisioned, then micro-operation storage capacity increases, but other cache resources become underutilized
Solution Approach 1:
The patent enables other caches to perform multiple functions by making them available to receive micro-operations. This increases micro-operation storage capacity while simultaneously maintaining the adaptability and versatility of cache resources, as the same caches continue to serve their original purposes when not used for micro-operation storage.
Data Source
AI summary
Techniques and mechanisms for selectively increasing or decreasing an amount of cache resources which are to be available for use in the provisioning of decoded micro-operations in a processor. In an embodiment, a processor core comprises both a first cache which is dedicated to caching micro-operations, and a second cache which is coupled to receive data, or non-decoded instructions. The core further comprises circuitry to monitor one or more cache performance characteristics of the core. Based on the one or more cache performance characteristics, the circuitry performs an evaluation to determine whether to increase—or alternatively, to decrease—the size of a pool of one or more caches which are to be available to receive micro-operations. In another embodiment, the second cache is added to the pool based on an indication of an overutilization of the first cache.