I'm experiencing very poor graphics performance under Windows 8/8.1/2012 when Hyper-V is enabled (hardware configuration below). I read anything I and Google could find on the topic but I haven't found a single straight answer that can explain the problems I'm seeing so I decided to ask for your help: where do I start looking for the issue, what tools can I use, how can I pinpoint the source of the problem - be it hardware, BIOS or software?
Tyan S2915 (latest BIOS, tried older ones too)
8x2gb DDR2 sticks
several 7970 cards (tried one at a time)
Windows 8.1 Pro
Quad-Core AMD Opteron(tm) Processor 8387
AMD64 Family 16 Model 4 Stepping 2, AuthenticAMD
HYPERVISOR - Hypervisor is present
SVM * Supports AMD hardware-assisted virtualization
NP * Supports AMD nested page tables (SLAT)
Everything from re-sizing windows to video playback and 3D apps is sluggish when Hyper-V is enabled (with zero VMs running). Think 10-12FPS at most instead of 70-90 and GPU usage stays under 20%. If I disable Hyper-V, performance returns to "normal": FPS goes up, GPU usage goes up too.
Most sources blame:
- lack of SLAT/RVI: shouldn't be an issue with the Shanghai 8387s; does the MB/northbridge (NF3600) play any role in this?
- "Hyper-V is designed for servers and won't run on.....such and such" nonsense; Win8 Hyper-V requires SLAT and should not introduce such high penalties - and it doesn't on other machines I tested (a couple but both are Intel/Nvidia based).
What I tried so far:
- lots of motherboard BIOS versions and settings
- fresh OS installs
- several Catalyst versions (14.1 is worse than earlier ones - resizing Windows Explorer windows is painful now)
Performance monitor/counters: ran many measurements with Hyper-V enabled/disabled but I couldn't find a "pattern" that could explain the slowdowns. According to Understanding High-End Video Performance Issues with Hyper-V - Ben Armstrong - Site Home - MSDN Blogs I should have seen spikes in TLB flushes if SLAT was not working; I don't see any spikes.
Windows Performance Recorder/Analyzer: I recorded Passmark's PerformanceTest (it's homescreen does 1200FPS without Hyper-V and about 250FPS with Hyper-V) with and without Hyper-V and tried to compare the results but I can't find a pattern here either; maybe I'm not looking for the right things. Any suggestions?
AMD codeXL: unfortunatelly, I get a BSOD when Hyper-V is enabled.