> -----Original Message----- > From: Flavio Leitner [mailto:f...@sysclose.org] > Sent: Wednesday, June 17, 2015 2:31 PM > To: Traynor, Kevin > Cc: Daniele Di Proietto; dev@openvswitch.org; Gray, Mark D > Subject: Re: [ovs-dev] Is this an issue for DPDK vhost rss? > > On Wed, Jun 17, 2015 at 01:18:29PM +0000, Traynor, Kevin wrote: > > > > > -----Original Message----- > > > From: Traynor, Kevin > > > Sent: Wednesday, June 17, 2015 10:12 AM > > > To: Flavio Leitner; Daniele Di Proietto > > > Cc: dev@openvswitch.org; Gray, Mark D > > > Subject: RE: [ovs-dev] Is this an issue for DPDK vhost rss? > > > > > > > > > > -----Original Message----- > > > > From: Flavio Leitner [mailto:f...@sysclose.org] > > > > Sent: Tuesday, June 16, 2015 6:28 PM > > > > To: Daniele Di Proietto > > > > Cc: Traynor, Kevin; dev@openvswitch.org; Gray, Mark D > > > > Subject: Re: [ovs-dev] Is this an issue for DPDK vhost rss? > > > > > > > > On Mon, Jun 15, 2015 at 05:55:13PM +0000, Daniele Di Proietto wrote: > > > > > On 15/06/2015 12:16, "Traynor, Kevin" <kevin.tray...@intel.com> > wrote: > > > > > >There is a dpdk patchset that contains a potential fix for this and > lots > > > > > >of > > > > > >other changes, but I haven't tested yet. > > > > > >https://urldefense.proofpoint.com/v2/url?u=http- > > > 3A__dpdk.org_ml_archives_d > > > > > >ev_2015-2DJune_018436.html&d=BQIFAg&c=Sqcl0Ez6M0X8aeM67LKIiDJAXVeAw- > > > YihVMN > > > > > >tXt- > > > uEs&r=SmB5nZacmXNq0gKCC1s_Cw5yUNjxgD4v5kJqZ2uWLlE&m=FDVPKa2SqwpyYOTmA2 > > > > > > > > > >zGdscCPa1FVdQG3Zbr4tHrp38&s=fjg7wArWvYLJlgEGKijK6W6ECAxGk660UrPF3rAr4Rs&e= > > > > > > > > I skimmed over the patchset and it is an ABI breaker, so I > > > > think the policy demands to announce it on 2.1 and merge only > > > > in 2.2 release. > > > > > > I tested with a subset of the patches and the ol_flags.rss bit is being > set > > > correctly. > > > > > > It could be merged and available in DPDK 2.1 with a config parameter. > > > However, > > > even with this we'd need to assess the rest of the changes and > compatibility > > > with OVS. > > > > > > > > > > > Maybe it is possible to separate the ol_flags fix into a > > > > smaller and simple patch to be accepted as bugfix yet in 2.1. > > > > > > That would be ideal. > > > > > > > > > > > > > > > > >> > Otherwise, should we avoid using the vectorized version? > > > > > >> > > > > > >> that's debatable - from a performance view it may be better to > leave > > > it > > > > > >>in > > > > > >> and take the hit elsewhere for the time being if there's a > possibility > > > > > >>that > > > > > >> it will be changed in DPDK later. > > > > > > > > > > > >With a loop to reset the rss after the rte_vhost_dequeue_burst() > call > > > I'm > > > > > >seeing a drop of ~100kpps in vhost performance. Rx vectoristion > gives a > > > > > >gain > > > > > >of about ~1 mpps on my system for the phy2phy cases. > > > > > > > > > > > >Using the ol_flags check is the right option when DPDK supports > setting > > > it > > > > > >correctly with rx vectorisation. In the meantime there's choice of > using > > > > > >the > > > > > >reset loop or removing rx vectorisation - what do you think? > > > > > > > > > > Thanks for sharing these results. I've observed that if OVS can't > use > > > the > > > > > RSS > > > > > hash and has to compute we lose ~2Mpps on a single flow phy2phy test. > > > > > > > > > > Despite this, I still think we should consider the ol_flags because: > > > > > > > > > > * DPDK drivers (other than ixgbe) should use ol_flags as well to mark > the > > > > > RSS hash as valid > > > > > * ixgbe_recv_pkts_vec() will report PKT_RX_RSS_HASH in future > releases > > > (the > > > > > patch you sent will be effective since DPDK 2.2, right?) > > > > > > > > I agree with the above. > > > > I'm also seeing a ~3 mpps drop in phy2phy when not using the hardware hash. > > It's a ~25% drop on phy2phy vs. a ~2.5% drop on the vhost interface with > the > > hash reset workaround. There may not be a DPDK fix that we can incorporate > > until towards the end of the year (DPDK 2.2?) so IMHO, with this size of > > performance drop it would be better to use the workaround until there's a > > DPDK fix. > > What happens if you just set of_flags in DPDK when there is a > valid hash with the proposed patch from Daniele?
I'm assuming performance would be fine with that. I haven't gone through the code to see if there's a simple DPDK patch to enable just that yet. > > fbl > _______________________________________________ dev mailing list dev@openvswitch.org http://openvswitch.org/mailman/listinfo/dev
