Re: Is sendfile all that sexy?

kuznet@ms2.inr.ac.ru
Sat, 20 Jan 2001 21:53:42 +0300 (MSK)


Hello!

> Actually, as long as there is no "struct page" there _are_ problems.
> This is why the NUMA stuff was brought up - it would require that there
> be a mem_map for the PCI pages.. (to do ref-counting etc).

I see.

Is this strong "no-no-no"? What is obstacle to allow "struct page"
to sit outside of mem_map (in some private table, or as full orphan)?
Only bloat of struct page with reference to some "page_ops" or something
more profound?

> It does work at least on some hardware. But no, I don't think you can
> depend on bursting (but I don't see why it couldn't work in theory).

I do not see too, but documents are pretty obscure explaining this.
MRM seems to be prohibited for pci-pci. But my education is still not
enough even to understand, whether MRM is required to burst
or this is fully orthogonal yet. 8)

Alexey
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