On Mon, Aug 29, 2016 at 08:32:55AM +0000, Xu, Qian Q wrote:
> I just ran a PVP test, nic receive packets then forwards to vhost PMD, and
> virtio user interface. I didn't see any performance gains in this scenario.
> All packet size from 64B to 1518B
> performance haven't got benefit from this patchset, and in fact, the
> performance dropped a lot before 1280B, and similar at 1518B.
40G nic?
> The TX/RX desc setting is " txd=64, rxd=128"
Try it with "txd=128", you should be able to set that value since the
vhost Tx indirect patch is merged.
--yliu
> for TX-zero-copy enabled case. For TX-zero-copy disabled case, I just ran
> default testpmd(txd=512, rxd=128) without the patch.
> Could you help check if NIC2VM case?
>
> -----Original Message-----
> From: dev [mailto:dev-bounces at dpdk.org] On Behalf Of Yuanhan Liu
> Sent: Tuesday, August 23, 2016 4:11 PM
> To: dev at dpdk.org
> Cc: Maxime Coquelin <maxime.coquelin at redhat.com>; Yuanhan Liu <yuanhan.liu
> at linux.intel.com>
> Subject: [dpdk-dev] [PATCH 0/6] vhost: add Tx zero copy support
>
> This patch set enables vhost Tx zero copy. The majority work goes to patch 4:
> vhost: add Tx zero copy.
>
> The basic idea of Tx zero copy is, instead of copying data from the desc buf,
> here we let the mbuf reference the desc buf addr directly.
>
> The major issue behind that is how and when to update the used ring.
> You could check the commit log of patch 4 for more details.
>
> Patch 5 introduces a new flag, RTE_VHOST_USER_TX_ZERO_COPY, to enable Tx zero
> copy, which is disabled by default.
>
> Few more TODOs are left, including handling a desc buf that is across two
> physical pages, updating release note, etc. Those will be fixed in later
> version. For now, here is a simple one that hopefully it shows the idea
> clearly.
>
> I did some quick tests, the performance gain is quite impressive.
>
> For a simple dequeue workload (running rxonly in vhost-pmd and runnin txonly
> in guest testpmd), it yields 40+% performance boost for packet size 1400B.
>
> For VM2VM iperf test case, it's even better: about 70% boost.
>
> ---
> Yuanhan Liu (6):
> vhost: simplify memory regions handling
> vhost: get guest/host physical address mappings
> vhost: introduce last avail idx for Tx
> vhost: add Tx zero copy
> vhost: add a flag to enable Tx zero copy
> examples/vhost: add an option to enable Tx zero copy
>
> doc/guides/prog_guide/vhost_lib.rst | 7 +-
> examples/vhost/main.c | 19 ++-
> lib/librte_vhost/rte_virtio_net.h | 1 +
> lib/librte_vhost/socket.c | 5 +
> lib/librte_vhost/vhost.c | 12 ++
> lib/librte_vhost/vhost.h | 103 +++++++++----
> lib/librte_vhost/vhost_user.c | 297
> +++++++++++++++++++++++-------------
> lib/librte_vhost/virtio_net.c | 188 +++++++++++++++++++----
> 8 files changed, 472 insertions(+), 160 deletions(-)
>
> --
> 1.9.0
