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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lazybum131 - Tuesday, February 14, 2006 - link
Actually, if you take into account the larger capacity battery on the T60, 56WHr compared 51 WHr, the T43 comes out ahead most of the time. The T60 has a 9.8% larger capacity battery, but with the fix it only comes out ahead 3.2%, 1.85%, 8.24% and 5.04%.Anand Lal Shimpi - Monday, February 13, 2006 - link
I'm looking into this issue myself and I will have an updated Core Duo performance article in the coming weeks that will address this as well as many other items. I wouldn't use the ASUS notebooks to compare Napa to Sonoma, especially given the internal USB 2.0 camera. I am hoping to do a Lenovo based Napa vs. Sonoma comparison that will hopefully make things a lot clearer.Take care,
Anand
JarredWalton - Monday, February 13, 2006 - link
I think that Napa allows a lower power setting, but you have to remember that two cores are still going to use more power than a single core when active. It might be interesting to see a test comparing Sonoma and Napa with the same CPU, as Dothan and Yonah both fix socket 479. There's also a question of the other peripherals, though: NIC, sound, screen, etc. all draw power. The newer Napa laptop from ASUS might have a better (re: brighter but more power hungry) LCD, for example, or a different HDD model. I don't know if they're strictly "identical" in other components, but a change of platform often involves other tweaks as well.NullSubroutine - Monday, February 13, 2006 - link
Id be more apt to say that the increase of the FSB and the second additional core are more likely the cause, because I think they did make sure the Asus laptops were exactly the same.IntelUser2000 - Tuesday, February 14, 2006 - link
Keep in mind that with laptops especially with power consumption there is so many variations to battery life problem. It could be that the implementation of the BIOS or voltage regulator is different across the two. Voltage regulator is said to be 5-10% of total power consumption, so differences in V-reg can make differences you are seeing.
Look here: http://www.hardwarezone.com/articles/view.php?id=1...">http://www.hardwarezone.com/articles/view.php?id=1...
Even with a faster CPU, MSI M635 with 1.8GHz Turion outperforms HP Compaq nx6125 with 2.0GHz Turion. It also gets better battery life even with X700.
I think 5% difference is well within the range.
huges84 - Monday, February 13, 2006 - link
Doh! I completely forgot about the dual vs single core issue. And your other points are valid as well.kmmatney - Monday, February 13, 2006 - link
Looks like I'll be using my old USB 1.1 mouse when I travel from now on.huges84 - Monday, February 13, 2006 - link
Yeah, a lot of people will be checking what version of USB their mouses are. I know I will be.Saist - Monday, February 13, 2006 - link
In reguards to THG, I was surprised to see a link as well.In reguards to AMD systems, I have a Turion on hand from Fujitsu (Lifebook S2000) and have been unable to duplicate the power loss from a default state with either a USB 2.0 external DVD drive, or a USB 2.0 Plextore ConvertX device.
I was also surprised to see that Anandtech didn't test any Turion systems themsevles in the article. But, having tested 2 Centrino systems of my own (one from Sager, the other from Dell), in addition to the Fujitsu, yes, it is time consuming.
Zebo - Monday, February 13, 2006 - link
Anand refuses to test new turions similarly equiped.. don't know why I've emailed him never heard back. Go to laptop logic.