Some Dude

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  1. So I've did some playing around with bench marking and my 8 core fx/unraid setup on win10. With NPT disabled I am seeing what you described as progressively worse multi-threaded performance when adding additional cpus. It's downright horrible in some tests with all 8 cores. Single threaded performance, however, seems to be pretty consistent with ~12-15% performance drop across the board. 4 cpus looks like the sweet spot for overall system performance. It seems to be a mixed bag though. My cinebench tests did not show this behavior and performance seemed to scale up pretty well as I added additional cores. I'm also running a Linux Mint 18.1 vm and while I saw some noticeable degradation in win10 (login time, internet browsing, some desktop apps, etc), disabling NPT seemed to improve the overall desktop experience and I was not able reproduce the same weird multi-threaded issues. So it looks like I'll be dealing with same issues with Ryzen... for a second I started to wander if I should hold off and wait a while longer to see if some of these things get ironed out before taking the dive. But then I realized that I've been with amd since the k5. What am going to do, go out and buy intel?
  2. I wouldn't think that pinning/unpinning the cpus would effect whether or not you could boot the vm. Also, are you isolating any cpus for the host? If so then you need use pinning, otherwise the vm will try and run all cpus on the host cpu. For instance if you isolcpus=1-15, then you have specify via pinning which cores between 1-15 you'd like the vm to use, otherwise the system will try to run all vm cores on cpu 0 which is the only core "visable" to the system. Imagine 12 cores trying to use one core. This would be a problem and might be causing the slower boot times the more cores you add. The only reason I have the cpu's unpinned is testing out the performance differences. Also, are you using iommu=pt and kvm.ignore_msrs=1? These helped me with win10 boot issues I was having (I think).
  3. Here is the relevant part of my win10 xml. I'm using host-passthough and I've removed any cpu pinning at the moment. <os> <type arch='x86_64' machine='pc-q35-2.7'>hvm</type> <loader readonly='yes' type='pflash'>/usr/share/qemu/ovmf-x64/OVMF_CODE-pure-efi.fd</loader> <nvram>/etc/libvirt/qemu/nvram/xxx_VARS-pure-efi.fd</nvram> </os> <features> <acpi/> <apic/> <hyperv> <relaxed state='on'/> <vapic state='on'/> <spinlocks state='on' retries='8191'/> <vendor_id state='on' value='none'/> </hyperv> <kvm> <hidden state='on'/> </kvm> </features> <cpu mode='host-passthrough'> <topology sockets='1' cores='4' threads='1'/> </cpu> <clock offset='localtime'> <timer name='hypervclock' present='yes'/> <timer name='hpet' present='no'/> </clock>
  4. I ran into this issue as well when tinkering with the params. Only the vm would usually boot the second try after killing it, and it was only the windows one that had the problem. I'm not having that issue right now, so maybe adding iommu=pt and/or kvm.ignore_msrs=1 will help with this. I'm not sure that the order makes a difference, but below is the current configuration that is working for me: default /syslinux/menu.c32 menu title Lime Technology, Inc. prompt 0 timeout 50 label unRAID OS menu default kernel /bzimage append initrd=/bzroot kvm-amd.npt=0 iommu=pt kvm.ignore_msrs=1 The redhat vfio-user list is what I'm following, I did see mention of the iommu mailing list, but I wasn't sure what list that was referring too. I've not been active in the discussions, just following along...
  5. There is an issue with AMD CPU's gaming/gpu performance and nested page tables. I'm currently running an fx cpu, but apparently this effects Ryzen processors as well (hope to join you guys with a Ryzen build in the coming weeks!). NPT can be disabled by appending "kvm-amd.npt=0" to the kernel parameters at boot. My current setup is an fx8320e with a gtx970 and gtx1050 passed through and I was struggling with framerates that were 50-75% worse than bare-metal before disabling NPT. The trade off is that you will give up the performance benefits of NPT. I've had a noticeable slowdown in some win10 desktop applications with it disabled. My hope is that this will be less noticeable on the ryzen platform.