On Mon, Jan 26, 2009 at 10:10:56PM -0800, David Miller wrote:

From: Evgeniy Polyakov <redacted>
Date: Tue, 27 Jan 2009 00:21:30 +0300

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Hi Jarek.

On Mon, Jan 26, 2009 at 08:20:36AM +0000, Jarek Poplawski (jarkao2@gmail.com) wrote:

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1. Network (tree) allocator
http://www.ioremap.net/projects/nta

I looked at this a bit, but alas I didn't find much for this Herbert's
idea of payload in fragments/pages. Maybe some kind of API RFC is
needed before this resurrection?

Basic idea is to steal some (probably a lot) pages from the slab
allocator and put network buffers there without strict need for
power-of-two alignment and possible wraps when we add skb_shared_info at
the end, so that old e1000 driver required order-4 allocations for the
jumbo frames. We can do that in alloc_skb() and friends and put returned
buffers into skb's fraglist and updated reference counters for those
pages; and with additional copy of the network headers into skb->head.

I think the main problem is to respect put_page() more, and maybe you
mean to add this to your allocator too, but using slab pages for this
looks a bit complex to me, but I can miss something.

We are going back and forth saying the same thing, I think :-)
(BTW, I think NTA is cool and we might do something like that
eventually)

The basic thing we have to do is make the drivers receive into
pages, and then slide the network headers (only) into the linear
SKB data area.

As a matter of fact, I wonder if these headers should be always
separated. Their "chunk" could be refcounted as well, I guess.

Jarek P.