This video describes the ‘Shared Page Cache’ (SPC) in GemStone Smalltalk. The SPC is a large chunk of memory that is shared by multiple GemStone processes and includes counters, real-time statistics, and copies of repository pages from disk. When a page is loaded into the SPC it is placed in a ‘frame.’ One performance issue is finding a free frame when a page needs to be loaded from disk. Special processes (“Free Frame Page Servers”) scan the SPC searching for free frames and adding them to a free frame list. Special processes exist (“Asynchronous Disk I/O Page Servers”) that look for dirty pages to write to disk.

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