Engineering Windows 7

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Engineering the Windows 7 “Windows Experience Index”

Engineering the Windows 7 “Windows Experience Index”

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We’re busy going through tons of telemetry from the many people that have downloaded and installed the Windows 7 beta around the world. We’re super excited to see the excitement around kicking the tires. Since most folks on the beta are well-versed in the hardware they use and very tuned into the choices they make, we’ve received a few questions about the Windows Experience Index (WEI) in Windows 7 and how that has been changed and improved in Windows 7 to take into account new hardware available for each of the major classes in the metric. In this post Michael Fortin returns to dive into the engineering details of the WEI.

The WEI was introduced in Windows Vista to provide one means across PCs to measure the relative performance of key hardware components. Like any index or benchmark, it is best used as a relative measure and should not be used to compare one measure to another. Unlike many other measures, the WEI merely measures the relative capability of components. The WEI only runs for a short time and does not measure the interactions of components under a software load, but rather characteristics or your hardware. As such it does not (nor cannot) measure how a system will perform under the your own usage scenarios. Thus the WEI does not measure performance of a system, but merely the relative hardware capabilities when running Windows 7.

We do want to caution folks in trying to generalize an “absolute” WEI as necessary for a given individual. We each have different tolerances or more importantly expectations for how a PC should perform and the same WEI might mean very different things to different individuals. To personalize this, I do about 90% of my work on a PC with a WEI of 2.0, primarily driven by the relatively low score for the gaming graphics component on my very low cost laptop. I run Outlook (with ~2GB of email), Internet Explorer (with a dozen tabs), Excel (with longs list of people on the development team), PowerPoint, Messenger (with video), and often I am running one of several LOB applications written in .NET. I feel with this type of workload and a PC with Windows 7 and that WEI my own brain and fingers continues to be my “bottleneck”. At the other end of the spectrum is my holiday gift machine which is a 25” all-in-one with a WEI of 5.1 (though still limited by gaming graphics, with subscores of 7.2, 7.2, 6.2, 5.1, 5.9). This machine runs Windows 7 64-bit and I definitely don’t keep it very busy even though I run MediaCenter in a window all the time, have a bunch of desktop gadgets, and run the PC as our print server (I use about 25% of available RAM and the CPU almost never gets above 10%).


The overall Windows Experience Index (WEI) is defined to be the lowest of the five top-level WEI subscores, where each subscore is computed using a set of rules and a suite of system assessment tests. The five areas scored in Windows 7 are the same as they were in Vista and include:

  • Processor
  • Memory (RAM)
  • Graphics (general desktop work)
  • Gaming Graphics (typically 3D)
  • Primary Hard Disk

Though the scoring areas are the same, the ranges have changed. In Vista, the WEI scores ranged from 1.0 to 5.9. In Windows 7, the range has been extended upward to 7.9. The scoring rules for devices have also changed from Vista to reflect experience and feedback comparing closely rated devices with differing quality of actual use (i.e. to make the rating more indicative of actual use.) We know during the beta some folks have noticed that the score changed (relative to Vista) for one or more components in their system and this tuning, which we will describe here, is responsible for the change.

For a given score range, we hope our customers will be able to utilize some general guidelines to help understand the experiences a particular PC can be expected to deliver well, relatively speaking. These Vista-era general guidelines for systems in the 1.0, 2.0, 3.0, 4.0 and 5.0 ranges still apply to Windows 7. But, as noted above, Windows 7 has added levels 6.0 and 7.0; meaning 7.9 is the maximum score possible. These new levels were designed to capture the rather substantial improvements we are seeing in key technologies as they enter the mainstream, such as solid state disks, multi-core processors, and higher end graphics adapters. Additionally, the amount of memory in a system is a determining factor.

For these new levels, we’re working to add guidelines for each level. As an example for gaming users, we expect systems with gaming graphics scores in the 6.0 to 6.9 range to support DX10 graphics and deliver good frames rates at typical screen resolutions (like 40-50 frames per second at 1280x1024). In the range of 7.0 to 7.9, we would expect higher frame rates at even higher screen resolutions. Obviously, the specifics of each game have much to do with this and the WEI scores are also meant to help game developers decide how best to scale their experience on a given system. Graphics is an area where there is both the widest variety of scores readily available in hardwaren and also the widest breadth of expectations. The extremes at which CAD, HD video, photography, and gamers push graphics compared to the average business user or a consumer (doing many of these same things as an avocation rather than vocation) is significant.

Of course, adding new levels doesn’t explain why a Vista system or component that used to score 4.0 or higher is now obtaining a score of 2.9. In most cases, large score drops will be due to the addition of some new disk tests in Windows 7 as that is where we’ve seen both interesting real world learning and substantial changes in the hardware landscape.

With respect to disk scores, as discussed in our recent post on Windows Performance, we’ve been developing a comprehensive performance feedback loop for quite some time. With that loop, we’ve been able to capture thousands of detailed traces covering periods of time where the computer’s current user indicated an application, or Windows, was experiencing severe responsiveness problems. In analyzing these traces we saw a connection to disk I/O and we often found typical 4KB disk reads to take longer than expected, much, much longer in fact (10x to 30x). Instead of taking 10s of milliseconds to complete, we’d often find sequences where individual disk reads took many hundreds of milliseconds to finish. When sequences of these accumulate, higher level application responsiveness can suffer dramatically.

With the problem recognized, we synthesized many of the I/O sequences and undertook a large study on many, many disk drives, including solid state drives. While we did find a good number of drives to be excellent, we unfortunately also found many to have significant challenges under this type of load, which based on telemetry is rather common. In particular, we found the first generation of solid state drives to be broadly challenged when confronted with these commonly seen client I/O sequences.

An example problematic sequence consists of a series of sequential and random I/Os intermixed with one or more flushes. During these sequences, many of the random writes complete in unrealistically short periods of time (say 500 microseconds). Very short I/O completion times indicate caching; the actual work of moving the bits to spinning media, or to flash cells, is postponed. After a period of returning success very quickly, a backlog of deferred work is built up. What happens next is different from drive to drive. Some drives continue to consistently respond to reads as expected, no matter the earlier issued and postponed writes/flushes, which yields good performance and no perceived problems for the person using the PC. Some drives, however, reads are often held off for very lengthy periods as the drives apparently attempt to clear their backlog of work and this results in a perceived “blocking” state or almost a “locked system”. To validate this, on some systems, we replaced poor performing disks with known good disks and observed dramatically improved performance. In a few cases, updating the drive’s firmware was sufficient to very noticeably improve responsiveness.

To reflect this real world learning, in the Windows 7 Beta code, we have capped scores for drives which appear to exhibit the problematic behavior (during the scoring) and are using our feedback system to send back information to us to further evaluate these results. Scores of 1.9, 2.0, 2.9 and 3.0 for the system disk are possible because of our current capping rules. Internally, we feel confident in the beta disk assessment and these caps based on the data we have observed so far. Of course, we expect to learn from data coming from the broader beta population and from feedback and conversations we have with drive manufacturers.

For those obtaining low disk scores but are otherwise satisfied with the performance, we aren’t recommending any action (Of course the WEI is not a tool to recommend hardware changes of any kind). It is entirely possible that the sequence of I/Os being issued for your common workload and applications isn’t encountering the issues we are noting. As we’ve said, the WEI is a metric but only you can apply that metric to your computing needs.

Earlier, I made note of the fact that our new levels, 6 and 7, were added to recognize the improved experiences one might have with newer hardware, particularly SSDs, graphics adapters, and multi-core processors. With respect to SSDs, the focus of the newer tests is on random I/O rates and their avoidance of the long latency issues noted above. As a note, the tests don’t specifically check to see if the underlying storage device is an SSD or not. We run them no matter the device type and any device capable of sustaining very high random I/O rates will score well.

For graphics adapters, both DX9 and DX10 assessments can be run now. In Vista, the tests were specific to DX9. To obtain scores in the 6 or 7 ranges, a graphics adapter must obtain very good performance scores, support DX10 and the driver must be a WDDM 1.1 driver (which you might have noticed are being downloaded in beta during the Windows 7 beta). For WDDM 1.0 drivers, only the DX9 assessments will be run, thus capping the overall score at 5.9.

For multi-core processors, both single threaded and multi-threaded scenarios are run. With levels 6 and 7, we aim to indicate that these systems will be rarely CPU bound for typical use and quite suitable for demanding processing tasks and multi-tasking. As examples, we anticipate many quad core processors will be able to score in the high 6 to low 7 ranges, and 8 core systems to be able to approach 7.9. The scoring has taken into account the very latest micro-processors available.

For many key hardware partners, we’ve of course made available additional details on the changes and why they were made. We continue to actively work with them to incorporate appropriate feedback.

--Michael Fortin

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  • That's ridiculous, there were games coming out that required 2GB already, and it wasn't that much. I'd expect, say, 4GB to be the minimum for a 5.0 and 8GB for an 6.0. Maybe with 2GB it should be clamped to 4.0. Now, there's the issue of needing 64-bit to address it all...

  • Good job! THANKS! You guys do a great website, and have some great contents. Keep on the good work.

  • Just as a suggestion to everyone on the Hard Drive max of 5.9 (which I also have), there are drives out now that are able to read/write around 800 mb/s so for a read/write speed of 150 mb/s it seems pretty reasonable to give a 5.9.

  • I have Q9550 2.83GHz, 8GB DDR2 667MHz RAM, Radeon HD4870 Graphics, and Hitachi 500GB (IDE!) with Windows 7 on it.

    CPU: 7.3

    Memory: 7.3

    Graphics: 7.5

    Gaming Graphics: 7.5

    HDD: 5.8

    Solid scores, although I've noted above others with the HD4870 (x2 sometimes!) whose graphics scores differ quite a bit - usually higher on the Graphics and lower on the Gaming Graphics.

    The WEI does seem to be hit and miss.

    I would really like to see under what criteria the subscores are calculated, e.g. upper limits for capping on components. My brother's GeForce 9600GT scores Graphics: 4.9, Gaming Graphics: 6.3, so I think the graphics must be capped by something missing either in hardware (e.g. pixel shader x.x?) It would be nice to find out this information.

  • I work for one of the major storage vedors (enterprise, not just HDDs). I wanted to also say that I'm disappointed Windows 7 doesn't let you dig deeper in to the score in the interface. The high level numbers are nice for the novice users, but it'd be nice to be able to get what caused the storage to be the number (poor sequential 4k writes vs sustained throughput across all tests for example.)

    Oh, and while I take issue with your presentation of performance with the WEI, major kudos on the Win 7 look, feel, and usability. I also really like the resource monitor even though I know that's been around since Vista.

    -- Win 7 64 ultimate on mine.

  • when i finish setup windows 7 enterprise and finished all myprogram i had run thewindows experience index and run good 3.5 after i had open update and  get run the new verision g41 for my board intel g41 express chipset  i have one problem but,i tried alot of many to run the windows experience index but,answer the windows experience index for system could not be computed could not measure video playback performance

  • My WinEIVersion is unkown  In XML files


  • my windows experience index freezes my pc during aero assessment. It was working when i had nvidia geforce 4 mx 440.BUT When i upgrade my video cardto nvidia geforce fx5200 ,it started freezes .Then i upgraded my video card again to nvidia geforce 6600 it still freezes . I have installed the latest video driver and i have installed the windows agian but this did not work .Please help me , I have windows 7 32-bit .

    My system is

    Intel pentium 4 @ 2.00 ghz

    1gb memory

    256mb nvidia geforce 6600 agp 4x

    please contact me at my phone no 00923325242554/03325242554 in pakistan

    or on my email

  • It's a damn shame you apparently cowed to hardware manufacturers yet again instead of calling them out for causing poor performance that will surely get blamed on Windows instead (Vista Capable and Intel anyone).  

    If you have an agonizingly slow laptop where your mouse cursor is frozen while the disk thrashes, I bet you have a Seagate.  Of course most will think, "Windows sucks" and want to buy a Mac.  I only learned this heuristic thanks to this post and running Windows 7 on my laptop during the beta, and it's a shame this rating change was reverted.  

    I replaced the drive and performance improved dramatically without any of these awful multi-second lockups.  Now I'm stuck with the issue on my completely-different work laptop as well, and sure enough, guess what I find when looking at Device Manager...

  • @Ronny49. If your HD4870x2 is only getting 6.3 for gaming graphics, it might be for the following reason. (I experienced a similar artificial capping with both my HD4870 and HD6950 initially).

    Go into Catalyst Control Centre, and make sure all gaming options (anti aliasing, anisotropic filtering etc.) options are set to maximum quality. I think if you don't, the WEI calculation is throttled back.

    It turned my HD6950's score from 6.0 to 7.9.

    My i7 950, 12GB RAM, HD6950 and OCZ Vertex 2E setup scores: 7.8/7.8/7.9/7.9/7.8. Sounds about right for a top-spec system.

  • Does anyone know if Group Policy can disable the Windows Experience Index? We haven't been able to run it since rolling out our latest Policy updates. Though nothing points or mentions WEI. Anyone?

  • Also, thought I would mention that this worked prior to joining to network domain. Clean boot did not help.

  • I've written about the importance of computer manufacturers embracing Windows Experience Index. You can read about it here:

  • There is a nice tool avilable for chaging windows 7 rating 'Windows Rating Changer' by jtechsoftwares Visit and download

  • There is a tool available to change windows experience index..

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