On Tue, Nov 25, 2014 at 2:01 PM, Steve Gordon <sgor...@redhat.com> wrote:
> ----- Original Message ----- > > From: "Daniel P. Berrange" <berra...@redhat.com> > > To: "Dan Smith" <d...@danplanet.com> > > > > On Thu, Nov 13, 2014 at 05:43:14PM +0000, Daniel P. Berrange wrote: > > > On Thu, Nov 13, 2014 at 09:36:18AM -0800, Dan Smith wrote: > > > > > That sounds like something worth exploring at least, I didn't know > > > > > about that kernel build option until now :-) It sounds like it > ought > > > > > to be enough to let us test the NUMA topology handling, CPU pinning > > > > > and probably huge pages too. > > > > > > > > Okay. I've been vaguely referring to this as a potential test vector, > > > > but only just now looked up the details. That's my bad :) > > > > > > > > > The main gap I'd see is NUMA aware PCI device assignment since the > > > > > PCI <-> NUMA node mapping data comes from the BIOS and it does not > > > > > look like this is fakeable as is. > > > > > > > > Yeah, although I'd expect that the data is parsed and returned by a > > > > library or utility that may be a hook for fakeification. However, it > may > > > > very well be more trouble than it's worth. > > > > > > > > I still feel like we should be able to test generic PCI in a similar > way > > > > (passing something like a USB controller through to the guest, etc). > > > > However, I'm willing to believe that the intersection of PCI and > NUMA is > > > > a higher order complication :) > > > > > > Oh I forgot to mention with PCI device assignment (as well as having a > > > bunch of PCI devices available[1]), the key requirement is an IOMMU. > > > AFAIK, neither Xen or KVM provide any IOMMU emulation, so I think we're > > > out of luck for even basic PCI assignment testing inside VMs. > > > > Ok, turns out that wasn't entirely accurate in general. > > > > KVM *can* emulate an IOMMU, but it requires that the guest be booted > > with the q35 machine type, instead of the ancient PIIX4 machine type, > > and also QEMU must be launched with "-machine iommu=on". We can't do > > this in Nova, so although it is theoretically possible, it is not > > doable for us in reality :-( > > > > Regards, > > Daniel > > Is it worth still pursuing virtual testing of the NUMA awareness work you, > nikola, and others have been doing? It seems to me it would still be > preferable to do this virtually (and ideally in the gate) wherever possible? > The more we can test in the gate and without real hardware the better. > > Thanks, > > Steve > > _______________________________________________ > OpenStack-dev mailing list > OpenStack-dev@lists.openstack.org > http://lists.openstack.org/cgi-bin/mailman/listinfo/openstack-dev >
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