Cache Line Write Suppression Using Unmodified Data Tracking
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Power consumption in multi-core/processor devices is limited by the energy-intensive operations such as write operations between cache and I/O components, which can be reduced by identifying and suppressing the writing of unmodified information in evicted cache lines.
Innovation Solution
Implementing tracking modules to identify unmodified information in caches and suppression modules to selectively disable write operations for such information, using bit vectors to indicate unmodified data and prevent unnecessary writing across different cache levels and I/O components.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If write operations are performed for all evicted cache lines, then data consistency is maintained, but power consumption increases
Solution Approach 1:
The patent applies local quality by differentiating between modified and unmodified data within cache lines. Instead of treating all evicted cache lines uniformly, the system tracks modification status at a finer granularity (byte-level or word-level) and selectively writes only the modified portions to lower cache levels or memory. This selective write approach maintains data consistency for modified data while avoiding unnecessary write operations for unmodified data, thereby reducing power consumption.
Solution Approach 2:
The patent implements partial action by performing write operations only on the necessary subset of data. The modification tracking mechanism identifies which specific bytes or words within evicted cache lines have been modified, and write operations are performed only for those specific portions rather than the entire cache line. This partial write strategy ensures data consistency is maintained for modified data while eliminating redundant write operations that consume power.
2Use of energy by moving object
If modification tracking is implemented, then power consumption is reduced, but device complexity increases
Solution Approach 1:
The patent applies segmentation by dividing the cache line into smaller addressable units (bytes or words) and maintaining separate modification status information for each unit. This segmentation allows the system to track modifications at a granular level without requiring complex global tracking mechanisms. The modification status is stored in compact bit vectors or similar structures, one for each cache line, which can be efficiently managed alongside the existing cache data.
Solution Approach 2:
The patent uses copying by maintaining a compact representation (copy) of the modification status alongside the actual cache data. Instead of modifying the original data structure, the system creates and maintains separate metadata (modification bits) that parallel the cache line structure. This copying approach allows for efficient tracking of modifications without fundamentally altering the existing cache architecture, thereby limiting the increase in device complexity.
3Use of energy by moving object
If selective write suppression is applied, then power consumption is reduced, but data consistency may be compromised
Solution Approach 1:
The patent implements feedback by continuously monitoring and tracking the modification status of cache data. The modification tracking mechanism provides real-time information about which data has been modified, and this feedback is used to dynamically control write operations. When a cache line is evicted, the system checks the modification status and only suppresses writes for unmodified portions, ensuring that data consistency is maintained for modified data while still achieving power savings.
Solution Approach 2:
The patent applies preliminary action by pre-tracking modifications before cache eviction occurs. The modification status is monitored and recorded during the cache's normal operation, so that when eviction is needed, the system already has the information required to make intelligent write decisions. This preliminary tracking ensures that no modified data is accidentally suppressed and that write operations are only suppressed for confirmed unmodified data, maintaining data consistency.
Data Source
AI summary
Embodiments of the present disclosure describe techniques and configurations to reduce power consumption using unmodified information in evicted cache lines. A method includes identifying unmodified information of a cache line stored in a cache of a processor, tracking the unmodified information using a bit vector comprising one or more bits to indicate the unmodified information of the cache line, and selectively suppressing a write operation or send operation for the unmodified information of the cache line that is evicted from the cache to an input/output (I/O) component coupled to the cache, the selective suppressing being based on the one or more bits, and the I/O component being an outer component external to the cache. Other embodiments may be described and/or claimed.