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    SubjectRe: [PLEASE-TESTME] Zerocopy networking patch, 2.4.0-1
    On Tue, Jan 09, 2001 at 02:31:13AM -0800, David S. Miller wrote:
    > Date: Tue, 9 Jan 2001 11:31:45 +0100
    > From: Christoph Hellwig <>
    > Yuck. A new file_opo just to get a few benchmarks right ... I
    > hope the writepages stuff will not be merged in Linus tree (but I
    > wish the code behind it!)
    > It's a "I know how to send a page somewhere via this filedescriptor
    > all by myself" operation. I don't see why people need to take
    > painkillers over this for 2.4.x. I think f_op->write is stupid, such
    > a special case file operation just to get a few benchmarks right.
    > This is the kind of argument I am hearing.
    > Orthogonal to f_op->write being for specifying a low-level
    > implementation of sys_write, f_op->writepage is for specifying a
    > low-level implementation of sys_sendfile. Can you grok that?

    Sure. But sendfile is not one of the fundamental UNIX operations...
    If there was no alternative to this I would probably have not said
    anything, but with the rw_kiovec file op just before the door I don't
    see any reason to add this _very_ specific file operation.

    An alloc_kiovec before and an free_kiovec after the actual call
    and the memory overhaed of a kiobuf won't hurt so much that it stands
    against a clean interface, IMHO.

    > Linus has already seen this. Originally he had a gripe because in an
    > older revision of the code used to allow multiple pages to be passed
    > in an array to the writepage(s) operation. He didn't like that, so I
    > made it take only one page as he requested. He had no other major
    > objections to the infrastructure.

    You get that multiple page call with kiobufs for free...


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