NVM Memory Reclamation via Write-Time Sorting

The patent changes the selection parameter from LRU (least recently used) to write time count. Instead of selecting pages based on access time, the system selects inactive NVM pages with the smallest write time counts for reclamation. This parameter change ensures that pages with fewer write operations are reclaimed first, preventing excessive wear on heavily written pages while maintaining efficient memory reclamation.

The patent applies different reclamation strategies to different types of memory pages. Specifically, it distinguishes between DRAM pages and NVM pages, and further categorizes NVM pages by their write time counts. The system selectively applies the write-time-based selection criterion to inactive NVM pages while using LRU for other pages, optimizing both reliability for NVM and overall reclamation efficiency.

The patent changes the reclamation selection parameter from access-based metrics to write-time-based metrics. By selecting inactive NVM pages with the minimum write time counts for reclamation, the system ensures that pages with fewer write operations are reclaimed first. This maintains wear balance across NVM pages while still satisfying memory capacity requirements through efficient reclamation.

The patent implements a selective discarding strategy where only inactive NVM pages with low write time counts are discarded for reclamation. The system identifies candidate pages based on write time criteria, selects those with minimum write times, and recovers them for reuse. This approach ensures that heavily written pages are preserved while still providing sufficient memory capacity through targeted reclamation of lightly written pages.