Propose to Use madvise API on Runtime Loader

[lin zuojian]

Hi Rich,
> I'm aware of this, but is it dropped or not? First you claimed the
> resident memory drops from the madvise call, but then you claimed it
> doesn't drop from the page cache. I think you need to explain this
> more clearly if there's going to be a discussion of the merits of your
> proposal.
> 
    It really drops the page tables, which alwarys belong to a process
    , not cache or other kernel usage.That would save some pages.
    But it does not drop from the page cache.
    And the accoutable memory, e.g. RSS, of a process drops.
    The page reclaiming process will reclaim these pages earlier.
    Because it access eariler.
--
Lin Zuojian