Re: Unexpected splice "always copy" behavior observed

From: Nick Piggin
Date: Tue May 18 2010 - 12:01:02 EST

On Tue, May 18, 2010 at 10:56:24AM -0500, Christoph Lameter wrote:
> On Wed, 19 May 2010, Nick Piggin wrote:
> > What would be needed is to have filesystem maintainers go through and
> > enable it on a case by case basis. It's trivial for tmpfs/ramfs type
> > filesystems and I have a patch for those, but I never posted it on.yet.
> > Even basic buffer head filesystems IIRC get a little more complex --
> > but we may get some milage just out of invalidating the existing
> > pagecache rather than getting fancy and trying to move buffers over
> > to the new page.
> There is a "migration" address space operation for moving pages. Page
> migration requires that in order to be able to move dirty pages. Can
> splice use that?

Hmm yes I didn't think of that, it probably could.

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