Re: [rfc][patch] unlock_page speedup

Andrew Morton
2008-12-19T07:34:14Z

On Fri, 19 Dec 2008 08:29:09 +0100 Nick Piggin <npiggin@suse.de> wrote:

> Introduce a new page flag, PG_waiters

Leaving how many? fs-cache wants to take two more.

How's about we actually work this out, then make PG_waiters the
highest-numbered free one?

PG_free1,
PG_free2,
...
PG_waiters
};

(or even something really sensitive, like PG_lru)

So that

a) we can see how many are left in a robust fashion and

b) we find out whether PG_waiters (PG_lru?) gets scribbled on by architectures
which borrow upper bits from page.flags for other nefarious purposes.

?