On Jan 24, 2014, at 6:33 AM, CARVER, PAUL <pc2...@att.com> wrote: > I agree that I’d like to see a set of use cases for this. This is the second > time in as many days that I’ve heard about a desire to have such a thing but > I still don’t think I understand any use cases adequately. > > In the physical world it makes perfect sense, LACP, MLT, > Etherchannel/Portchannel, etc. In the virtual world I need to see a detailed > description of one or more use cases. > > Shihanzhang, why don’t you start up an Etherpad or something and start > putting together a list of one or more practical use cases in which the same > VM would benefit from multiple virtual connections to the same network. If it > really makes sense we ought to be able to clearly describe it.
I can think of one potential use case. In testing I have been unable to saturate a 10g link using a single VM. Even with multiple streams, the best I have been able to do (using virtio and vhost_net is about 7.8g. I have been told with CPU pinning that can be pushed up into the high nines, but pinning is not a great fit for cloud. I am not totally sure where the bottleneck is, but I have a guess that it relates to maxing out a single cpu on the host side pushing traffic from the virtual interface into the physical one. I have been able to saturate a 10g link by using multiple vms, but it occurs to me that having two separate vnics might allow you to push the full 10g from a single vm. I have not tested this, but I wouldn’t be surprised if it is true. Vish > > -- > Paul Carver > VO: 732-545-7377 > Cell: 908-803-1656 > E: pcar...@att.com > Q Instant Message > > From: Day, Phil [mailto:philip....@hp.com] > Sent: Friday, January 24, 2014 09:11 > To: OpenStack Development Mailing List (not for usage questions) > Subject: Re: [openstack-dev] [nova]Why not allow to create a vm directly with > two VIF in the same network > > I agree its oddly inconsistent (you’ll get used to that over time ;-) - but > to me it feels more like the validation is missing on the attach that that > the create should allow two VIFs on the same network. Since these are both > virtualised (i.e share the same bandwidth, don’t provide any additional > resilience, etc) I’m curious about why you’d want two VIFs in this > configuration ? > > From: shihanzhang [mailto:ayshihanzh...@126.com] > Sent: 24 January 2014 03:22 > To: openstack-dev@lists.openstack.org > Subject: [openstack-dev] [nova]Why not allow to create a vm directly with two > VIF in the same network > > I am a beginer of nova, there is a problem which has confused me, in the > latest version, it not allowed to create a vm directly with two VIF in the > same network, but allowed to add a VIF that it network is same with a existed > VIF'network, there is the use case that a vm with two VIF in the same > network, but why not allow to create the vm directly with two VIF in the same > network? > > > _______________________________________________ > OpenStack-dev mailing list > OpenStack-dev@lists.openstack.org > http://lists.openstack.org/cgi-bin/mailman/listinfo/openstack-dev
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