On 2015/6/10 23:34, Gray, Mark D wrote:
On 10/06/2015 12:48, "Gray, Mark D" <mark.d.g...@intel.com> wrote:
The vhost port won't generate an RSS hash because it is a virtual NIC.
It doesn't cause a problem, just make the pkt fall into a slow path,
should we
fix it?
Thanks for investigating this. We should definitely fix it.
The flag ol_flags may be useful for OVS or let DPDK fix this in vhost
rcv.
How do you propose that this would work? The RSS would still have to be
generated in software.
A simple solution would be to reset the RSS hash inside
netdev_dpdk_vhost_rxq_recv(). Other netdev providers that do not
support reading the RSS hash (netdev-linux, netdev-bsd) call
dp_packet_set_rss_hash(pkt, 0) on every received packet.
I thought Dongjun was suggesting that we should generate a hash? I agree that
it should be reset on every received packet. I upstreamed something similar for
dpdkr ports. The proposal above seems good to me.
Sorry for my vague expression, Mark. Resetting RSS on every received
packet is good enough to me.
Could rte_vhost_dequeue_burst() do this resetting? Doing the same
thing, seems that netdev_dpdk_vhost_rxq_recv() needs an additional loop
but rte_vhost_dequeue_burst() need not.
This would probably have a small impact on performance, but it's better than
trashing the exact match cache.
I don't believe there's anything that DPDK can do here (like resetting the
hash when the packet is freed), but please correct me if I'm wrong.
Thoughts?
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