On Sun, Mar 27, 2011 at 01:12, Simon Riggs <simon(at)2ndquadrant(dot)com> wrote:
>> At the same time I would
>> change count_nondeletable_pages() so that it uses a forward scan direction
>> (if that leads to a speedup).
+1.
> Do we need that? Linux readahead works in both directions doesn't it?
> Guess it wouldn't hurt too much.
Yes, probably. AFAIK, RHEL 5 cannot readahead in backward scans.
It might be improved in the latest kernel, but it would be safe
not to rely on kernels except simple forward scans.
--
Itagaki Takahiro