On Wed, May 3, 2017 at 10:37 AM, Matthias Ehrenfeuchter <[email protected]> wrote: > Hi, > > There are a lot of messages/threads out there about bad performance while > using AMDs Ryzen with KVM GPU passthrough. It revolves all on > enabling/disabling npt, while enabled overall VM performance is nice but the > GPU performance gives me about 20% (and a lot of drops to zero GPU usage, > while CPU/Disk/Ram also doing nothing) compared to npt disabled. But while > npt is disabled overall VM performance is like beeing on 4x86 with floppy > disk as only storage. (Ex. it takes 2 seconds just to open startmenu while > host and vm are in idle, and neither CPU pinning, changing CPU model, > changing storage device nor using hugepages changed anything). > > So everything I read pointed to a bug in the npt implementation? Anything I > could do to get closer to the "thing" issuing this? > > Best Regards > > efeu > _______________________________________________ > iommu mailing list > [email protected] > https://lists.linuxfoundation.org/mailman/listinfo/iommu
I heard from Joerg that it might be related to a lower intercept rate being used when NPT is enabled, but we haven't been able to find a way to trace that to confirm. _______________________________________________ iommu mailing list [email protected] https://lists.linuxfoundation.org/mailman/listinfo/iommu
