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    SubjectRe: Data corruption issue with splice() on 2.6.27.10
    On Wed, Jan 07, 2009 at 03:46:29PM +0300, Evgeniy Polyakov wrote:
    > On Wed, Jan 07, 2009 at 11:42:46PM +1100, Herbert Xu (herbert@gondor.apana.org.au) wrote:
    > > > Doesn't your tcp fallbacks to kernel_sendmsg() without sg in
    > > > tcp_sendpage()? And then just feeds data into the stack the same way it
    > > > happens with send() i.e. by copying it.
    > >
    > > Good point. Did he check GSO though? GSO will always enable SG
    > > on the socket regardless of the netdev's setting. And if the device
    > > started out with SG enabled then recent kernels will enable GSO
    > > by default.
    >
    > Willy, what was the kernel you are tested no-accel behaviour and what
    > were the gso settings?

    kernel is 2.6.27.10 + a few patches (squashfs, etc..., nothing related to
    this area). My ethtool is a bit old and does not report GSO. I'll download
    and rebuild a more recent one and retest.

    > Can you add a simple single print into tcp_sendpage() to determine if
    > content was copied or fed into do_tcp_sendpages() otherwise?

    Yes, will do that too.

    Willy



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