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    SubjectRe: kernel > 2.1.36 & nfs
    Alan Cox wrote:

    : The header can be in multiple parts. Also stuff like the NFS rpc code would
    : need a rewrite to cope with fragmented rpc headers

    As far as NFS is concerned, the only area where avoiding fragment
    disassembly makes sense is in READ replies. The NFS code already
    plays some tricks with buffer alignment. Because it knows how big the
    RPC reply header is, it can set up the receive iovec so that the data
    portion goes directly into the page cache. All that's needed thus is the
    ability to do a copy+checksum from the fragment list to the iovec.

    While it would also be nice to be able to handle fragment lists on NFS
    WRITE in the server, this requires that we have access to the packet
    checksum as computed by the card. It also requires that file_operations
    provides readv()/writev() because I can't mess with the page cache
    directly on the server.

    I think we can avoid those pathological cases (IP IP IP..) cited by Alan
    if we pass on the fragments only for packets where we know it's
    some well-behaved protocol (UDP, TCP), and the header is completely
    contained in the first fragment.

    Olaf Kirch | --- o --- Nous sommes du soleil we love when we play | / | \ sol.dhoop.naytheet.ah

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      Last update: 2005-03-22 13:39    [W:0.017 / U:3.988 seconds]
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