Messages in this thread | | | Date | Tue, 17 Apr 2012 11:27:01 +0800 | From | Jason Wang <> | Subject | Re: [PATCH 6/6] vhost_net: don't poll on -EFAULT |
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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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