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Windows 8 resource usage and DPC latency

Posted: Mon May 14, 2012 10:44 pm
by UltimateOutsider
I keep hearing people say how fast and lean Windows 8 is, compared to what they were using before, and this has always surprised me. I’ve been working with it for eight months, and while it starts up quicker than Windows 7, it never felt any more streamlined than Win 7. While there’s no way I’m installing it on my DAW systems, I decided to do some tests on a DAW-capable laptop to see if it really was any smaller or more efficient than Windows 7.

My test system was a Dell Latitude E6410 laptop, with the following specifications:

Processor: Intel Core i5 M 520
Cores: 2
Threads: 4
Clock (GHz): 2.4
RAM (GB): 2
OS (Win 7): Windows 7 Pro SP-1 64-bit
OS (Win 8): Windows 8 8301 64-bit

Both my Windows 7 and Windows 8 installs were clean, fresh installs with the basic drivers required to support the computer’s devices, with no additional services or startup apps. Also, in both cases, I had the “High Performance” power scheme selected in the Power Options control panel. This scheme disables all OS-configurable CPU power saving features. (Unfortunately, like most OEM systems, the Dell’s BIOS doesn’t let you disable any of the BIOS-configurable CPU features.)

To see whether Windows 8 was really any smaller or more streamlined than Windows 7, I recorded resource usage after logging in and remaining idle for a couple of minutes (to give all startup processes plenty of time to do their thing). Additionally, I ran the DPC Latency checker for a while on each system.

Here’s the raw data:

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Observations
  • Windows 8 uses a tiny bit more RAM than Windows 7. It’s a negligible amount, but it’s definitely not LESS RAM than Windows 7, which many people seem to have been implying.
  • My system had three fewer PROCESSES running under Windows 8 than Windows 7, but 11 more SERVICES running than Windows 7. (Multiple services can be managed by a single service host process.)
  • Windows 8 had nearly 6500 more handles open than Windows 7 during my tests. Handles can represent open files, registry keys, critical sections, events, etc. They are a sign that the processes running in the background are actually doing more stuff than on Windows 7.
  • The above was not surprising, although it does seem to go against many assertions I’ve heard that Windows 8 is smaller than Windows 7. It’s actually a little bigger and busier than Windows 7. But the really odd stuff was the DPC latency stats:
    Image

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  • Average latency on Windows 8 was over nine times Windows 7's average. The highest latency spike reported on Windows 8 was more than four times the highest spike on Windows 7. But if you take a look at the screenshots, even though Windows 8’s latency numbers are all worse than Windows 7’s, they’re far more consistent. Not as many peaks and valleys, although the overall response time is rather poor in comparison. Windows 8’s best response time is worse than Windows 7’s worst. The erratic Windows 7 behavior is what you normally see on a computer where you can’t disable an Intel processor’s power saving features. The Windows 8 behavior, while bad, is flat like you’d see on a desktop DAW where you are able to shut all that stuff off.
This is just one test on one PC. I’m really eager to hear if anyone has done any 1:1 DAWBench comparisons on the same system between Win 7 and Win 8. And I’m very curious to see what happens to those DPC Latency numbers as Win 8 approaches Gold status.

But anyway, I am definitely not installing Win 8 on my DAW systems now. Even if i LIKED Windows 8 (which I don’t), I currently see zero performance incentives to upgrading, and in fact that DPC latency is a current major disincentive- although I really want to see a real-world DAW test to confirm its impact.

Re: Windows 8 resource usage and DPC latency

Posted: Tue May 29, 2012 5:37 pm
by Sonarcade
thanks for looking into this and for reporting back. I'm not super happy about Windows 8's performance either. I hope they patch this up before launch.