Re: [PLEASE-TESTME] Zerocopy networking patch, 2.4.0-1

["David S. Miller" <davem@redhat.com>]

   From: Trond Myklebust <trond.myklebust@fys.uio.no>
   Date: 09 Jan 2001 14:52:40 +0100

   I don't really want to be chiming in with another 'make it a kiobuf',
   but given that you already have written 'do_tcp_sendpages()' why did
   you make sock->ops->sendpage() take the single page as an argument
   rather than just have it take the 'struct page **'?

It was like that to begin with.  But to do it cleanly you have to pass
in not a vector of "pages" but a vector of "page+offset+len" triplets.

Linus hated it, and I understood why, so I reverted the API to be
single page based.

   I would have thought one of the main interests of doing something
   like this would be to allow us to speed up large writes to the
   socket for ncpfs/knfsd/nfs/smbfs/...

This is what TCP_CORK/MSG_MORE et al. are all for, things get
coalesced perfectly.  Sending in a vector of pages seems nice, but
none of the page cache infrastructure works like this, all of the core
routines work on a page at a time.  It actually simplifies a lot.

The writepage interface optimizes large file writes to a socket just
fine.

Later,
David S. Miller
davem@redhat.com

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