On Mon, 25 Sep 2000, Ingo Molnar wrote:
>
> On Mon, 25 Sep 2000, Rik van Riel wrote:
>
> > 2) you are right, we /can/ schedule when __GFP_IO isn't set, this is
> > mistake ... now I'm getting confused about what __GFP_IO is all
> > about, does anybody know the _exact_ meaning of __GFP_IO ?
>
> __GFP_IO set to 1 means that the allocator can afford doing IO implicitly
> by the page allocator. Most allocations dont care at all wether swap IO is
> started as part of gfp() or not. But a prominent counter-example is
> GFP_BUFFER, which is used by the buffer-cache/fs layer, and which cannot
> do any IO implicitly. (because it *is* the IO layer already, and it is
> already trying to do IO.) The other reason are legacy lowlevel-filesystem
> locks like the ext2fs lock, which cannot be taken recursively.
Hmmm, doesn't GFP_BUFFER simply imply that we cannot
allocate new buffer heads to do IO with??
(from reading buffer.c, I can't see much of a reason
why we couldn't start write IO on already allocated
buffers...)
regards,
Rik
--
"What you're running that piece of shit Gnome?!?!"
-- Miguel de Icaza, UKUUG 2000
http://www.conectiva.com/ http://www.surriel.com/
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