Re: [Lhms-devel] [RFC 0/6] Swapless Page Migration V1: Overview

[Christoph Lameter <clameter@sgi.com>]

On Wed, 5 Apr 2006, Lee Schermerhorn wrote:

> Does this approach still allow "migrate-on-fault" for anon pages?

I am not aware of something that would be in the way.

> Especially, in the case where the migrating page has >1 pte referencing
> it?  How will the fault handler find all of the pte's referencing the
> old page?  Actually, I don't think we'd want to burden the task whose

The fault handler can find these via the reverse maps.

> fault caused the migration with finding and replacing and replacing all
> pte's referecing the old page.  Using a real cache, this isn't a problem
> because we replace the old page with a new one in the cache, and the
> cache ptes reference the cache entry.  Tasks are free to fault in a real
> pte for the new page at any time.  I'd hate to lose this capability.  I
> believe that this is one of the reasons that Marcello used a real idr-
> based cache for the migration cache.

We never allow a faulting in of the new page before migration is 
complete. The replacing of the swap ptes with real ptes was always done 
after migration was complete. Same thing here.

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