Hot-N-Cold PCP

[ref. PLKA p146, p183, ]

per_cpu_pageset structure. each zone has pageset[NR_CPUS].
NR_CPUS = 1 (uni-processor), 2-32 (smp32), 2-64 (smp64)

per_cpu_pageset -> per_cpu_pages[2] ... 0:hot, 1:cold

per_cpu_pages { count, high, batch (chunk size for BA), list }
... low watermark: 0, high watermark: high (PLKAfig3.6)

list of pages are kept track of by page->lru field.

I will take the page from the back of the list, test it and put it in the front of the list.

(Performance) I can have a free page reserve to fill up pcp quickly.