Re: [patch 7/7] mm: reduce rmap overhead for ex-KSM page copiescreated on swap faults

[Johannes Weiner]

On Wed, Dec 19, 2012 at 02:01:19AM -0500, Simon Jeons wrote:
> On Mon, 2012-12-17 at 13:12 -0500, Johannes Weiner wrote:
> > When ex-KSM pages are faulted from swap cache, the fault handler is
> > not capable of re-establishing anon_vma-spanning KSM pages.  In this
> > case, a copy of the page is created instead, just like during a COW
> > break.
> > 
> > These freshly made copies are known to be exclusive to the faulting
> > VMA and there is no reason to go look for this page in parent and
> > sibling processes during rmap operations.
> > 
> > Use page_add_new_anon_rmap() for these copies.  This also puts them on
> > the proper LRU lists and marks them SwapBacked, so we can get rid of
> > doing this ad-hoc in the KSM copy code.
> 
> Is it just a code cleanup instead of reduce rmap overhead?

Both.
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