[ovs-dev] [PATCH v2 0/2] vHost Dequeue Zero Copy
jan.scheurich at ericsson.com
Wed Oct 11 16:23:09 UTC 2017
These improvements look very good. I would expect even bigger improvements for big packets, as long as we don't hit some link bandwidth limitations. But at least the vhost-vhost cases should benefit.
Have you also tested larger packet sizes?
I plan to review your patches.
> -----Original Message-----
> From: ovs-dev-bounces at openvswitch.org [mailto:ovs-dev-bounces at openvswitch.org] On Behalf Of Ciara Loftus
> Sent: Wednesday, 11 October, 2017 16:22
> To: dev at openvswitch.org
> Subject: [ovs-dev] [PATCH v2 0/2] vHost Dequeue Zero Copy
> This patch enables optional dequeue zero copy for vHost ports.
> This gives a performance increase for some use cases. I'm using
> the cover letter to report my results.
> vhost (vm1) -> vhost (vm2)
> Using testpmd to source (txonly) in vm1 and sink (rxonly) in vm2.
> 4C1Q 64B packets: 5.05Mpps -> 5.52Mpps = 9.2% improvement
> vhost (virtio_user backend 1) -> vhost (virtio_user backend 2)
> Using 2 instances of testpmd, each with a virtio_user backend
> connected to one of the two vhost ports created in OVS.
> 2C1Q 1518B packets: 2.59Mpps -> 3.09Mpps = 19.3% improvement
> vhost -> phy
> Using testpmd to source (txonly) and sink in the NIC
> 1C1Q 64B packets: 6.81Mpps -> 7.76Mpps = 13.9% improvement
> phy -> vhost -> phy
> No improvement measured
> This patch is dependent on the series below which fixes issues with
> mempool management:
> v2 changes:
> * Mention feature is disabled by default in the documentation
> * Add PHY-VM-PHY with vHost dequeue zero copy documentation guide
> * Line wrap link to DPDK documentation
> * Rename zc_enabled to dq_zc_enabled for future-proofing
> * Mention feature is available for both vHost port types in the docs
> * In practise, rebooting the VM doesn't always enable the feature if
> enabled post-boot, so update the documentation to suggest a shutdown
> rather than a reboot. The reason why this doesn't work is probably
> because the total downtime during reboot isn't enough to allow a vhost
> device unregister & re-register with the new feature, so when the VM
> starts again it doesn't pick up the new device as it hasn't been
> re-registered in time.
> Ciara Loftus (2):
> netdev-dpdk: Helper function for vHost device setup
> netdev-dpdk: Enable optional dequeue zero copy for vHost User
> Documentation/howto/dpdk.rst | 29 +++++
> Documentation/topics/dpdk/vhost-user.rst | 35 ++++++
> NEWS | 3 +
> lib/netdev-dpdk.c | 202 +++++++++++++++++++++----------
> vswitchd/vswitch.xml | 11 ++
> 5 files changed, 218 insertions(+), 62 deletions(-)
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