I reckon a spare CPU could happily
- pre-zero some pages, preferably spread over the range of page colours.
- move pages around to make space for multi-page allocations.
- checksum pages to find duplicates and merge them in the background
> > Compressive paging
> > Before writing a page out to swap, compress it.
> > IPC through page remapping
>
> Slow. Only worth it if the message is big enough (last time I heard, the
> cut-over point was around 8KB).
Uusually the overhead of TLB flushes or the need for inter-CPU TLB
flush messages is given as the reason.
But there are cases when those can be shown to be not necessary.
Like when you read a page, and the pte is not marked "accessed" yet.
No TLB flush required.
Similarly when you write a page and its marked "dirty" but not
"accessed" -- I'm not sure if this combination (written but not read) is
flagged by CPUs though.
-- Jamie
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