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    SubjectRe: [PATCH 6/6] vhost_net: don't poll on -EFAULT
    On 04/16/2012 09:39 PM, Michael S. Tsirkin wrote:
    > On Mon, Apr 16, 2012 at 04:28:10PM +0800, Jason Wang wrote:
    >> > On 04/16/2012 03:16 PM, Michael S. Tsirkin wrote:
    >>> > >On Mon, Apr 16, 2012 at 02:08:33PM +0800, Jason Wang wrote:
    >>>> > >>Currently, we restart tx polling unconditionally when sendmsg()
    >>>> > >>fails. This would cause unnecessary wakeups of vhost wokers as it's
    >>>> > >>only needed when the socket send buffer were exceeded.
    >>> > >Why is this a problem?
    >> >
    >> > This issue is when guest driver is able to hit the -EFAULT, vhost
    >> > discard the the descriptor and restart the polling. This would wake
    >> > vhost thread and repeat the loop again which waste cpu.
    > Does same thing happen if we get an error from copy from user?
    >

    Right, so do you think it makes sense that we only restart polling on
    -EAGAIN or -ENOBUFS?


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