Re: [PATCH] [Request for inclusion] Filesystem in Userspace

Nikita Danilov
2004-11-18T20:17:26Z

Linus Torvalds <torvalds@osdl.org> writes:

[...]

>
> We actually had (for a short while) code that tracked the dirty bit in
> software (ie make it unwritable by default, and take the write fault), but
> people showed that that was actually a real performance problem on some
> loads.

Dirtiness can be tracked for a fraction of pages (for example, make pte
unwritable when page crosses active/inactive list boundary, or
alike). This will allow kernel to guarantee that there really is _known_
amount of clean pages in the system, without taking a lot of unnecessary
faults.

[... notes on kernel development methodology skipped ...]

>
> Linus

Nikita.