Re: [dpdk-dev] [PATCH v2 0/5] virtio: Tx performance improvements

[Stephen Hemminger <stephen@networkplumber.org>]

On Fri, 4 Mar 2016 06:18:17 +0000
"Xie, Huawei" <huawei.xie@intel.com> wrote:

> On 1/14/2016 9:49 PM, Xie, Huawei wrote:
> > On 1/6/2016 8:04 PM, Thomas Monjalon wrote:
> >> 2016-01-05 08:10, Xie, Huawei:
> >>> On 10/26/2015 10:06 PM, Xie, Huawei wrote:
> >>>> On 10/19/2015 1:16 PM, Stephen Hemminger wrote:
> >>>>> This is a tested version of the virtio Tx performance improvements
> >>>>> that I posted earlier on the list, and described at the DPDK Userspace
> >>>>> meeting in Dublin. Together they get a 25% performance improvement for
> >>>>> both small packet and large multi-segment packet case when testing
> >>>>> from DPDK guest application to Linux KVM host.
> >>>>>
> >>>>> Stephen Hemminger (5):
> >>>>>   virtio: clean up space checks on xmit
> >>>>>   virtio: don't use unlikely for normal tx stuff
> >>>>>   virtio: use indirect ring elements
> >>>>>   virtio: use any layout on transmit
> >>>>>   virtio: optimize transmit enqueue
> >>>> There is one open why merge-able header is used in tx path. Since old
> >>>> implementation is also using the merge-able header in tx path if this
> >>>> feature is negotiated, i choose to ack the patch and address this later
> >>>> if not now.
> >>>>
> >>>> Acked-by: Huawei Xie <huawei.xie@intel.com>
> >>> Thomas:

Resending them now. I don't understand the issue with merge-able header.
Virtio negotiation is symmetric, if receiver is using merge-able header
then the transmitter needs to send it also.