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SubjectRe: async network I/O, event channels, etc
On Thu, Jul 27, 2006 at 02:31:56AM -0700, David Miller ( wrote:
> From: Evgeniy Polyakov <>
> Date: Thu, 27 Jul 2006 12:58:13 +0400
> > Btw, according to DMA allocations - there are some problems here too.
> > Some pieces of the world can not dma behind 16mb, and someone can do it
> > over 4gb.
> I think people take this "DMA" in Ulrich's interface names too
> literally. It is logically something different, although it could be
> used directly for this purpose.
> View it rather as memory you have by some key based ID, but need to
> explicitly map to access directly.

I mean here, that it is possible to have those Ulrich's dma regions to
be used as a real dma regions, and showed that it is not a good idea.

> > Those physical pages can be managed within kernel and userspace can map
> > them. But there is another possibility - replace slab allocation for
> > network devices with allocation from premapped pool.
> > That naturally allows to manage that pool for AIO needs and have
> > zero-copy sending and receiving support. That is what I talked in
> > netchannel topic when question about allocation/freeing cost in atomic
> > context arised. I work on that solution, which can be used both for
> > netchannels (and full userspace processing) and usual networking code.
> Interesting idea, and yes I have been watching you stress test your
> AVL tree code :))

Tests are completed - actually it required 12 a4 papers filled with
small circles and numbers to prove it is correct, overnight run was just
for clarifications :)

Evgeniy Polyakov
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