Open Stack

On 06/21/2018 07:50 AM, Mooney, Sean K wrote:
>> -----Original Message-----
>> From: Jay Pipes [mailto:jaypipes at gmail.com]

>> Side question... does either approach touch PCI device management
>> during live migration?
>>
>> I ask because the only workloads I've ever seen that pin guest vCPU
>> threads to specific host processors -- or make use of huge pages
>> consumed from a specific host NUMA node -- have also made use of SR-IOV
>> and/or PCI passthrough. [1]
>>
>> If workloads that use PCI passthrough or SR-IOV VFs cannot be live
>> migrated (due to existing complications in the lower-level virt layers)
>> I don't see much of a point spending lots of developer resources trying
>> to "fix" this situation when in the real world, only a mythical
>> workload that uses CPU pinning or huge pages but *doesn't* use PCI
>> passthrough or SR-IOV VFs would be helped by it.

> [Mooney, Sean K]  I would generally agree but with the extention of include dpdk based vswitch like ovs-dpdk or vpp.
> Cpu pinned or hugepage backed guests generally also have some kind of high performance networking solution or use a hardware
> Acclaortor like a gpu to justify the performance assertion that pinning of cores or ram is required.
> Dpdk networking stack would however not require the pci remaping to be addressed though I belive that is planned to be added in stine.

Jay, you make a good point but I'll second what Sean says...for the last few 
years my organization has been using a DPDK-accelerated vswitch which performs 
well enough for many high-performance purposes.

In the general case, I think live migration while using physical devices would 
require coordinating the migration with the guest software.

Chris