Re: [PATCH 2.5.43-mm2] New shared page table patch

[Gerrit Huizenga]

In message <[e-mail]>, > : Andrew Morton writes:
> Rik van Riel wrote:
> > 
> > ...
> > In short, we really really want shared page tables.
> 
> Or large pages.  I confess to being a little perplexed as to
> why we're pursuing both.

Large pages benefit the performance of large applications which
explicity take advantage of them (at least today - maybe in the
future, large pages will be automagically handed out to those that
can use them).  And, as a side effect, they reduce KVA overhead.
Oh, and at the moment, they are non-pageable, e.g. permanently stuck
in memory.

On the other hand, shared page tables benefit any application that
shares data, including those that haven't been trained to roll over
and beg for large pages.  Shared page tables are already showing large
space savings with at least one database.

gerrit