Intel Core Duo USB Issue: A Mischaracterized Bug
by Anand Lal Shimpi on February 13, 2006 1:40 PM EST- Posted in
- Laptops
The Fix
The Microsoft Knowledge Base article that references the USB power drain problem also provides a solution to the problem, a simple registry edit that prevents the USB devices from keeping the processor from moving to lower power states. The entire text of the KB article was actually anonymously posted in a Slashdot thread, and thus, is now publicly available. As with any changes to your Windows Registry, be sure to hang onto a backup copy and make any modifications at your own risk:
The Microsoft Knowledge Base article that references the USB power drain problem also provides a solution to the problem, a simple registry edit that prevents the USB devices from keeping the processor from moving to lower power states. The entire text of the KB article was actually anonymously posted in a Slashdot thread, and thus, is now publicly available. As with any changes to your Windows Registry, be sure to hang onto a backup copy and make any modifications at your own risk:
A Windows XP SP2-based portable computer uses its battery power more quickly than you expect when a USB 2.0 device is connectedUnfortunately, the solution isn't completely ready for public deployment, as there are apparently still some scenarios where it doesn't fix the problem. There may be issues with the problem re-appearing after putting your system to sleep, which are presently being worked on. However, for the majority of situations, this simple registry modification should, in theory, take care of things. With the solution in hand, and five notebooks to play with, we went to work.
View products that this article applies to.
Partner Only Article Article ID : 899179
Last Review : July 12, 2005
Revision : 1.0
Important: This article contains information about how to modify the registry. Make sure to back up the registry before you modify it. Make sure that you know how to restore the registry if a problem occurs. For more information about how to back up, restore, and modify the registry, click the following article number to view the article in the Microsoft Knowledge Base:
256986 (https://premier.microsoft.com/kb/256986/) Description of the Microsoft Windows registry
SYMPTOMS
Consider the following scenario. You install Microsoft Windows XP Service Pack 2 (SP2) on a portable computer. Then, you connect a USB 2.0 device to the computer. In this scenario, the computer uses its battery power more quickly than you expect.
CAUSE
Windows XP SP2 installs a USB 2.0 driver that initializes any connected USB device. However, the USB 2.0 driver leaves the asynchronous scheduler component continuously running. This problem causes continuous instances of memory access that prevent the computer from entering the deeper Advanced Configuration and Power Interface (ACPI) processor idle sleep states. These processor idle sleep states are also known as C states. For example, these include the C3 and C4 states. These sleep states are designed, in part, to save battery power. If an otherwise idle portable computer cannot enter or maintain the processor idle sleep states, the computer uses its battery power more quickly than you expect.
RESOLUTION
Warning: Serious problems might occur if you modify the registry incorrectly by using Registry Editor or by using another method. These problems might require that you reinstall your operating system. Microsoft cannot guarantee that these problems can be solved. Modify the registry at your own risk. To resolve this problem, add the EnIdleEndpointSupport entry to the USB registry key. To do this, follow these steps:STATUS
- Click Start, click Run, type regedit, and then click OK.
- Locate, and then click the following registry subkey:
HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\Servic es\USB
Note: If the USB subkey does not exist, create it. To do this, follow these steps:
a. Select the Services key. On the Edit menu, point to New, and then click Key.
b. Type USB in the New Key #1 box to name the new key "USB."- Right-click USB, point to New, and then click DWORD Value.
- In the New Value #1 box that appears, type EnIdleEndpointSupport, and then press ENTER.
- Right-click EnIdleEndpointSupport, and then click Modify.
- In the Value data box, type 1, leave the Hexadecimal option selected, and then click OK.
- Quit Registry Editor.
Microsoft has confirmed that this is a problem in the Microsoft products that are listed in the "Applies to" section.
APPLIES TO
Microsoft Windows XP Service Pack 2, when used with:
- Microsoft Windows XP Professional
- Microsoft Windows XP Home Edition
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Anand Lal Shimpi - Monday, February 13, 2006 - link
It's not a refusal to test, we're simply not sent any for review :) My next article will be a look at Core Duo vs. Turion performance on the desktop, but I'm still working on securing notebook review units. I would like to see if this issue does impact AMD systems as well, and to what degree.After the Core Duo vs. Turion piece, if we still haven't gotten a Turion notebook in house I'll just buy one for this comparison.
Take care,
Anand
havokprod - Monday, February 13, 2006 - link
Does this problem surface with SP1??DigitalFreak - Monday, February 13, 2006 - link
Microsoft has supposedly known about this since at least July 2005. WTF? Why hasn't this been fixed yet?scavio - Monday, February 13, 2006 - link
It must have been difficult to mention and actually link to Tom's, I'm glad to see professionalism still lives.Very nice job on the article, it looks as though you guys went the extra mile and actually did the work to try figure out what was going on. I read the Tom's article a couple of weeks ago and although they uncovered an important issue they seemed to think they could try to get to the bottom of it with phone calls rather than getting their hands dirty and taking the time to test things themselves.
hergieburbur - Tuesday, February 14, 2006 - link
While the technical aspects of this article are intriging, I think there is too much editorial opinion added on top of that.I think the main reason they post the link to Toms is to dispute the claim Tom's supposedly made that this was a Core Duo issue. That is not what the original article stated, though several times in this article there are thinly veiled allusions to that supposed claim.
I think that tech sites should spend a little more time focusing on themselves and the products they review, and a little less trying to show how they are better than the rest. That goes for all sites. You work speaks for itself.
Anand Lal Shimpi - Tuesday, February 14, 2006 - link
The reason for linking the THG article was to avoid taking credit for a discovery that I did not make. They were the first to stumble upon the issue and it was their article that inspired a deeper investigation, which eventually resulted in this article.The point of this article wasn't to show how we were somehow better, but to address the mischaracterization of the problem. The THG results show a tremendous penalty on their Core Duo notebook due to the issue but a relatively small penalty on their Sonoma platform; this article was designed to explain why that was and hopefully clear up the very common misconception that this is predominantly a Core Duo problem.
The problem is that lots of people linked to that first article, and a very large number of those links incorrectly referred to the problem as a Core Duo issue based on the results that were originally presented. In reality, this problem appears to be nothing more than a Microsoft issue that impacts both Core Duo and Pentium M systems (I'm trying to figure out if it impacts Turion systems as well) but it was grossly mischaracterized in its public acception. I don't really care whose fault that is (personally I believe it's the fault of those who linked to the original article without thoroughly reading it), but I do care that the right information gets out there, which is what this article was designed to do.
I learned long ago that the best you can do is to put your best foot forward and let the reader decide on their own how they feel about you. I'm not trying to shape anyone's view of another site through my work, I'm just trying to get the most accurate information out there.
Take care,
Anand
DigitalFreak - Monday, February 13, 2006 - link
That's why Tomshardware sucks and Anandtech doesn't. That and other things *cough*bias *cough*.Anand Lal Shimpi - Monday, February 13, 2006 - link
Be nice guys, if it weren't for the original THG article it would've taken much longer for this investigation to even happen. I just wanted to make sure that the bug was properly characertized and even more importantly, I want to actually see a fully functional fix from Microsoft that works even out of standby.Take care,
Anand
Zebo - Monday, February 13, 2006 - link
Careful back in the day TOMs revealed many of intels buggy hardware (i820, MTH, crashing dualcores ...)bupkus - Monday, February 13, 2006 - link
Look, I just read the intro and the conclusion, and I don't even own a laptop, but...[see subject], I do have an external hard drive and plans to get a laptop.