Intel Core Duo USB Issue: A Mischaracterized Bug
by Anand Lal Shimpi on February 13, 2006 1:40 PM EST- Posted in
- Laptops
Final Words
First of all, it's important to characterize the impact of the USB 2.0 asynchronous scheduler bug on both Core Duo and Pentium M based systems. Using the Lenovo T60 and T43 as comparison points, we found that without the fix, adding a bus-powered USB device such as a memory stick reduced battery life anywhere from 18 - 28%. In the case of the T43, a 28% reduction in battery life for simply plugging in a USB 2.0 device is beyond ridiculous. In the case of both notebooks, applying Microsoft's fix gives you almost all of your battery life back. The only decrease is due to actual power used by the device and any polling that may be happening as a result of the device being installed.
It is also extremely important that we point out the existence of this bug on all of the platforms that we tested; in other words, this is not exclusively a Core Duo problem. In fact, in the case of the T60/T43, the Sonoma based T43 actually lost a larger percentage of its battery life due to the asynchronous scheduler bug than the Napa based T60. We saw the same results with the ASUS notebooks. With only the integrated USB 2.0 camera connected, the ASUS Napa notebook lost 17% of its battery life due to the bug, while the Sonoma based W5A lost 25.5%. Once again, implying that this is a Core Duo issue alone is simply incorrect; the problem affects Sonoma platforms just as much, if not more, than Core Duo platforms. Based on the results that we've seen in our perfmon analysis, we tend to believe Microsoft's assessment that the problem would exist on any system that spent any time in C3 or lower power states.
Thankfully, the Microsoft fix does seem to work pretty well. The only downside is that the problem re-appears after bringing your notebook out of stand-by. Although a simple reboot will fix the problem once more, it's not a practical long term solution. Unfortunately, we have absolutely no idea when a true fix will be put in place. Until Microsoft releases a fix, we can only suggest that all notebook users, regardless of your CPU, either implement the temporary fix that we outlined in this article or be very conscious of leaving USB 2.0 devices connected while on battery power.
First of all, it's important to characterize the impact of the USB 2.0 asynchronous scheduler bug on both Core Duo and Pentium M based systems. Using the Lenovo T60 and T43 as comparison points, we found that without the fix, adding a bus-powered USB device such as a memory stick reduced battery life anywhere from 18 - 28%. In the case of the T43, a 28% reduction in battery life for simply plugging in a USB 2.0 device is beyond ridiculous. In the case of both notebooks, applying Microsoft's fix gives you almost all of your battery life back. The only decrease is due to actual power used by the device and any polling that may be happening as a result of the device being installed.
It is also extremely important that we point out the existence of this bug on all of the platforms that we tested; in other words, this is not exclusively a Core Duo problem. In fact, in the case of the T60/T43, the Sonoma based T43 actually lost a larger percentage of its battery life due to the asynchronous scheduler bug than the Napa based T60. We saw the same results with the ASUS notebooks. With only the integrated USB 2.0 camera connected, the ASUS Napa notebook lost 17% of its battery life due to the bug, while the Sonoma based W5A lost 25.5%. Once again, implying that this is a Core Duo issue alone is simply incorrect; the problem affects Sonoma platforms just as much, if not more, than Core Duo platforms. Based on the results that we've seen in our perfmon analysis, we tend to believe Microsoft's assessment that the problem would exist on any system that spent any time in C3 or lower power states.
Thankfully, the Microsoft fix does seem to work pretty well. The only downside is that the problem re-appears after bringing your notebook out of stand-by. Although a simple reboot will fix the problem once more, it's not a practical long term solution. Unfortunately, we have absolutely no idea when a true fix will be put in place. Until Microsoft releases a fix, we can only suggest that all notebook users, regardless of your CPU, either implement the temporary fix that we outlined in this article or be very conscious of leaving USB 2.0 devices connected while on battery power.
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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.