Messages in this thread | | | Date | Tue, 29 Jan 2002 13:08:12 -0800 (PST) | From | Linus Torvalds <> | Subject | Re: Note describing poor dcache utilization under high memory pressure |
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On Tue, 29 Jan 2002, Oliver Xymoron wrote: > > fork: > detach page tables from parent
- leave the option ot just mark them read-only on architectures that support it (ie x86, I think alpha does this too).
> retain pointer to "backing page tables" in parent and child > update use count in page tables
You want to copy the top-level page table directory (with the "present bit" disabled or something), not just retain a pointer to it. Otherwise you just get really confused after two fork() calls, where you can have multiple "backing page tables".
> "prefault" tables for current stack and instruction pages in both parent > and child
Don't unconditionally prefault. There are many potentially useful things that do _not_ want to do this, for example snapshot creation.
So the generic "do_fork()" thing should _not_ do prefaulting, although "sys_fork()" may well choose to do it.
Linus
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