In mem snapshot based GC

[dzavalishin]

Do not free snapshot memory image, map it in a separate address space, run full GC there.

See #129

Possibly should scan through kernel DS address space to check for links from kernel to obj mem? Scan allocated physmem and vaddr pages too?

[dzavalishin]

hal_page_control( add_space_id (pool id?), ... )

• addr_space_obj_off
• addr_space_obj_on
• addr_space_obj_gc - prev generation of objects for GC
• ADDR_SPACE_ALL - change in all maps, but only out of obj space

[dzavalishin]

Use snap verification infrastructure for it Need some kind of cache - use pool for pages and hash tab for map of addr to pool item

[dzavalishin]

It is unclear how to prevent situation:

• obj a used

• snap

• big GC runs on snap and finds a to be free

• obj a freed by refcount

• new obj created @ addr of a

• big GC finishes and kills a

• generations? per snap?

[dzavalishin]

TODO: Need refcnt GC to be run before snapshot - just a good occasion and, possibly, less mem to pageout.

NB! need some way to request disk io barrier from here

[dzavalishin]

Keep state in persistent memory! Map address to object info