I hit the search engines in earnest and found that these problems were prevalent across a fairly wide range of graphics cards. We enlisted Dell’s help and they told us that they do not certify that Hyper-V will work on any laptops. More precisely, they clarified the primary support concern is that future driver releases may not work with Hyper-V even if we find a model that works with today’s drivers. At this point we were considering a pricier Precision model and they put us in touch with their Precision product team in Texas. They were most helpful but we were told that Dell themselves do not use Hyper-V on laptops except for demonstration purposes and they simply use it as a server for connected workstations, so they would never experience the same graphics issues. Dell kindly offered to let us test our development build on various models at their campus if we agreed to share the results with them, but before we could arrange that visit, Windows Server 2008 R2 SP1 Beta* was released and I upgraded my machine in order to test out Dynamic Memory.

As I was installing it I had a chat with my colleague (and serial early adopter) Lambros Vasiliou to gauge his impressions. He mentioned his favourite improvement is that the known Hyper-V host graphics performance issues are either gone or greatly mitigated. This is an issue that’s been repeatedly discussed in our organisation since we moved from a hotchpotch of virtualisation technologies to Hyper-V as our standard development build last year. It’s probably the single thing that irritates our users of this system more than anything else.

I did some testing myself with videos playing and moving windows about with Windows Key + Arrow hot keys. The results were fairly impressive – without doubt a big improvement. One thing that still behaved poorly on my Dell XPS M1330 (with NVIDIA GeForce 8400GS) is full-screen YouTube, Vimeo, etc. The CTRL+ALT+DEL redraw operation seems a bit sluggish still as well. I noticed that my PowerPoint Presenter View was better, but still not 100% responsive.

I also tested on the Dell Latitude E6410 (with NVIDIA NVS 3100M). Not only is the previously-mentioned blue screen fixed and the graphics generally improved in the same ways as on the XPS, but the full-screen in-browser video and CTRL+ALT+DEL are instantaneous. One possible explanation for this different experience is that the Latitude has a processor with SLAT, but I can’t validate that at all yet… because I can’t find any information whatsoever about why/how this has changed!

I think it’s unlikely that these changes are related to RemoteFX (since the XPS M1330 does not have a processor with SLAT and I never enabled it on the Latitude E6410). I would expect RemoteFX to improve the experience connecting to the guests, not the Hyper-V root partition (although it’s possible that this improvement is somehow related). I’ve tried pinging Virtual PC Guy and posted this query on the SP1 Beta TechNet forum but so far the community can only confirm that this is indeed working on a number of different models including a Mac (drill down in the links on the TechNet thread for more information). One way or the other this is great news, but I’m finding the lack of information about these changes quite maddening given the amazing detail that’s been produced for the Dynamic Memory launch. I’d really appreciate further insights if anyone can reveal the internals.

* A few notes regarding the Service Pack 1 Beta installation process:

1. The links on the SP1 Beta page are a bit confusing. You should be aware that if you click the “Evaluate Windows Server 2008 R2 and SP1 Beta” link you will be taken to a page with a “Download Windows Server 2008 R2 Trial Software” section at the top. “Download SP1 Beta Software” is beneath that section. This is what you want. If you click the first link you will initiate a download of the full Windows Server 2008 R2 (SP0) installer. If you “upgrade” your system using that installer you’ll wind up with a nice new trial version of SP0. AGH. Starting again from the links in the right section I was able to run a small installer that presents the updates to Windows Update and that has all worked fine, so I’d recommend that route. Alternately the Service Pack can be downloaded stand-alone. I did that for my second install and it worked fine too. Also note the Windows Server 2008 R2 SP1 Beta Reviewer’s Guide, “to evaluate the core features of Windows Server 2008 R2 SP1 Beta release in your environment”.
2. If you use Forefront you will need to uninstall it in order to install SP1 Beta, so make sure to remember to reinstall it afterwards.
3. When I installed the Service Pack my screen went black for about ten minutes following the first reboot. Be prepared for this. You’ll see plenty of ongoing disk activity but nothing on the screen. Fairly disconcerting, but perhaps this is all a part of these same video changes.

• Microsoft’s approach to Dynamic Memory is fundamentally different than VMWare’s overcommitment, in that VMWare doesn’t trust information about memory usage from within the guest, whereas Microsoft’s implementation is based around an awareness of the amount and type of memory that’s being used at all times.
• Dynamic Memory will work by Adding/Removing memory.
  • Adding memory is enabled through a new synthetic memory driver.
  • Removing memory that’s not being used is done with ballooning.
  • Memory is now assigned with a few new values:
    • Startup memory is the amount of memory assigned to a VM, which is also the minimum memory the VM will consume (default value is 512 MB).
    • Maximum memory limits how much memory a VM can consume.
    • Priority can be assigned to specific VMs in order to make sure that they receive available memory before other lower-priority VMs.
    • A Memory Buffer can be set to reserve memory for specific VMs, for instance if they need extra memory for file caching.
• Hyper-V Manager adds two new columns.
  • Current Memory identifies how much memory the VM is consuming.
  • Memory Availability identifies the difference between how much memory a VM has vs. wants in a +/-% figure.
    • When the availability goes negative, the Windows guest will start to work with the lesser amount of memory that’s now available to it (via paging, etc).
    • Negative availability will result in reduced performance, but the systems will continue to function.
• Memory is now reserved for the root partition in a different way, so that dynamic memory won’t bring down the host.
  • This amount can be configured with a new registry key based on how the root partition is being used, for instance if it’s your desktop OS.
• As Dynamic Memory is used more, the chances of spanning NUMA nodes increases (on NUMA systems).
  • He points out that different systems have vastly different Back Channel performance, so the impact of NUMA Spanning can be negligible or drastic.
  • In SP1, NUMA Spanning can be disabled (if desired).
• Dynamic Memory also supports Large Pages, which are likely to become more common with virtualised Exchange/SQL.
  • VMWare cannot overcommit these pages.
• I’ve asked if there are specific processor requirements. I’ll be interested to see how/if this supports processors that don’t have SLAT.

• It’s not an issue on processors with SLAT, but these are only just hitting the market in laptops in the near future
• It’s not an issue with the SVGA driver
  • I’ve asked if the SVGA driver might ever offer multi-monitor support. He’s looking in to it. This might be a great compromise until processors with SLAT become ubiquitous
• This same problem occurs in all native Hypervisors
  • Virtual PC and VMWare Workstation do not have the same problem but they are Type 2 hypervisors and do not offer the same performance as Hyper-V

So… there’s still no conclusive solution but it’s good to have the full context of the problem. For more background on why this matters for SharePoint see my previous post on the matter. ]]> http://tristanwatkins.com/index.php/the-definitive-word-on-hyper-v-high-end-graphics-performance/feed/ 1 http://tristanwatkins.com/index.php/hyper-v-graphics-performance-is-in-on-the-way-if-you-need-a-new-laptop/?utm_source=rss&utm_medium=rss&utm_campaign=hyper-v-graphics-performance-is-in-on-the-way-if-you-need-a-new-laptop http://tristanwatkins.com/index.php/hyper-v-graphics-performance-is-in-on-the-way-if-you-need-a-new-laptop/#comments Wed, 23 Sep 2009 23:12:21 +0000 Tristan Watkins http://tristanwatkins.com/?p=247 Dell announced today that they are releasing Alienware and Studio laptops with Intel Core i7 processors. Why is this worth regurgitating? The Core i7 processors feature the Nehalem processor microarchitecture, which means that Hyper-V V2 (in Windows Server 2008 R2) can take advantage of SLAT (Second Level Address Translation). SLAT is implemented as EPT (Extended Paging Tables) in Intel technology and NPT (Nested Paging Tables) for AMD. Here’s Microsoft’s summary of the new Hyper-V support for SLAT:

The new Hyper-V also adds performance enhancements that increase virtual machine performance and power consumption. Hyper-V now supports Second Level Address Translation (SLAT), which uses new features on today’s CPUs to improve VM performance while reducing processing load on the Windows Hypervisor and new Hyper-V VMs will also consume less power by virtue of the new Core Parking feature implemented into Windows Server 2008 R2.

VitualizationAdmin.com adds a bit more to that:

Using NPT or EPT, AMD-V and Intel VT processors can maintain and perform the two levels of address space translations required for each virtual machine in hardware, reducing the complexity of the Windows Hypervisor and the context switches needed to manage virtual machine page faults. As a result, Windows Server 2008 R2 Hyper-V provides better scalability of Hyper-V servers.

But what’s really important is that this solves the Hyper-V graphics performance problem for new laptops.  Scott Havens summed up the graphics issue nicely. Actually it was his comments on the Virtual PC Guy blog entries that first drew my attention to this caveat. Here’s his take on the same issue as it regards laptops and he fleshes out some more of the complexities around this issue – but as I say, Dell has announced the new laptops today, so we aren’t far off!

For those of us who are unlikely to get new laptops any time soon, it’s worth reviewing my original assessment. One thing that Scott’s articles pointed out for me that hadn’t really sunk in for me yet is that this isn’t just an issue for SharePoint 2010 – but for Windows Server 2008 R2 full-stop, as it is also x64-only. Oh, and it’s worth considering a Windows 7 and Windows Server 2008 R2 with Hyper-V dual-boot if you’ll be doing anything massively graphics-intensive. This is actually how Virtual PC Guy describes his laptop setup.