Intel Core Duo USB Issue: A Mischaracterized Bug
by Anand Lal Shimpi on February 13, 2006 1:40 PM EST- Posted in
- Laptops
Problem #3 - The fix doesn't always work
We've proved the problem exists, confirmed that it affects more than just Core Duo systems, and have posted Microsoft's solution - so why even bother with an article?
The problem is that the fix isn't exactly perfect yet. The biggest problem that we've seen thus far is that while applying the fix gives you back the vast majority of your lost battery life, it won't remain active coming out of suspend. Once you apply the fix, you are set for as long as that key remains in your registry. However, if you put your notebook into stand-by, and when it comes out of stand-by, the fix will no longer be active. The only solution at this point is to reboot your system, which causes the registry to be re-read, and the fix will continue to work normally.
We confirmed this by once again looking at Perfmon with the C3 residence extension:
While the current workaround is better than nothing, it's still not completely resolved. We still need a real fix from Microsoft.
The Results
While we've already proved that the bug is platform independent, as well as showcased that the fix does work (somewhat), below we have data to show you the potential impact of the bug and what you gain back by implementing the fix on each of the five notebooks that we tested.
First up is the Napa based ASUS W5F; keep in mind that this platform features an integrated USB 2.0 camera, so the asynchronous scheduler is active even with no external USB devices connected:
You can see that the fix gives you back a good deal of your battery life. Keep in mind that the run-to-run variation of Mobile Mark 2005's Reader 2002SE test can be in the 3 - 5% range, so smaller differences should be ignored. Note the gain in battery life in the Northing Connected and Mouse (USB 1.0) columns. These gains are completely because of the integrated USB 2.0 camera.
While we're on ASUS, let's look at their Sonoma based W5A, also featuring an integrated USB 2.0 camera:
As you'd expect, the W5A behaves very similarly to the W5F. With the default (Nothing Connected) configuration receiving a huge increase in battery life after the fix was applied, you can see why the two ASUS notebooks are not an ideal test platform for measuring the impact of this bug.
We also tested the Dell Inspiron E1705:
Interestingly enough, the E1705 doesn't actually gain all that much battery life from the fix. We're still working on finding out why this is the case. For what it's worth, the E1705 has an integrated USB 2.0 hub that, like the ASUS systems and their integrated camera, complicates the issue. A lot of this problem may be up to the aggressiveness of the power management designed by the notebook maker, but we'll be working with Dell on our final review of the E1705 to figure out exactly what's going on here.
The final pair of notebooks that we compared are the Lenovo T60 and T43, the "cleanest" of the five in that they do not have any integrated USB 2.0 devices. First up, the T60:
The T60 behaves exactly as you would expect it to, with the notebook getting back virtually all of its battery life when paired with the External HDD with the fix applied. We don't know why the Inspiron didn't do the same, but since the ASUS and Dell systems both featured integrated USB 2.0 devices, we can't really predict how they are supposed to react.
The T43 also behaves as expected:
We've proved the problem exists, confirmed that it affects more than just Core Duo systems, and have posted Microsoft's solution - so why even bother with an article?
The problem is that the fix isn't exactly perfect yet. The biggest problem that we've seen thus far is that while applying the fix gives you back the vast majority of your lost battery life, it won't remain active coming out of suspend. Once you apply the fix, you are set for as long as that key remains in your registry. However, if you put your notebook into stand-by, and when it comes out of stand-by, the fix will no longer be active. The only solution at this point is to reboot your system, which causes the registry to be re-read, and the fix will continue to work normally.
We confirmed this by once again looking at Perfmon with the C3 residence extension:
While the current workaround is better than nothing, it's still not completely resolved. We still need a real fix from Microsoft.
The Results
While we've already proved that the bug is platform independent, as well as showcased that the fix does work (somewhat), below we have data to show you the potential impact of the bug and what you gain back by implementing the fix on each of the five notebooks that we tested.
First up is the Napa based ASUS W5F; keep in mind that this platform features an integrated USB 2.0 camera, so the asynchronous scheduler is active even with no external USB devices connected:
| ASUS W5F (Napa/Core Duo) | Nothing Connected | USB Drive (USB 2.0) | External HDD (USB 2.0) | Mouse (USB 1.0) |
| Normal | 219 | 205 | 214 | 216 |
| With Fix | 264 | 249 | 255 | 250 |
You can see that the fix gives you back a good deal of your battery life. Keep in mind that the run-to-run variation of Mobile Mark 2005's Reader 2002SE test can be in the 3 - 5% range, so smaller differences should be ignored. Note the gain in battery life in the Northing Connected and Mouse (USB 1.0) columns. These gains are completely because of the integrated USB 2.0 camera.
While we're on ASUS, let's look at their Sonoma based W5A, also featuring an integrated USB 2.0 camera:
| ASUS W5A (Sonoma/Pentium M) | Nothing Connected | USB Drive (USB 2.0) | External HDD (USB 2.0) |
| Normal | 204 | 199 | 218 |
| With Fix | 273 | 260 | 268 |
As you'd expect, the W5A behaves very similarly to the W5F. With the default (Nothing Connected) configuration receiving a huge increase in battery life after the fix was applied, you can see why the two ASUS notebooks are not an ideal test platform for measuring the impact of this bug.
We also tested the Dell Inspiron E1705:
| Dell Inspiron E1705 (Napa/Core Duo) | Nothing Connected | USB Drive (USB 2.0) | External HDD (USB 2.0) |
| Normal | 154 | 130 | 133 |
| With Fix | 155 | 135 | 137 |
Interestingly enough, the E1705 doesn't actually gain all that much battery life from the fix. We're still working on finding out why this is the case. For what it's worth, the E1705 has an integrated USB 2.0 hub that, like the ASUS systems and their integrated camera, complicates the issue. A lot of this problem may be up to the aggressiveness of the power management designed by the notebook maker, but we'll be working with Dell on our final review of the E1705 to figure out exactly what's going on here.
The final pair of notebooks that we compared are the Lenovo T60 and T43, the "cleanest" of the five in that they do not have any integrated USB 2.0 devices. First up, the T60:
| Lenovo T60 (Napa/Core Duo) | Nothing Connected | USB Drive (USB 2.0) | External HDD (USB 2.0) | Mouse (USB 1.0) |
| Normal | 286 | 235 | 245 | 272 |
| With Fix | 290 | 275 | 289 | 271 |
The T60 behaves exactly as you would expect it to, with the notebook getting back virtually all of its battery life when paired with the External HDD with the fix applied. We don't know why the Inspiron didn't do the same, but since the ASUS and Dell systems both featured integrated USB 2.0 devices, we can't really predict how they are supposed to react.
The T43 also behaves as expected:
| Lenovo T43 (Sonoma/Pentium M) | Nothing Connected | USB Drive (USB 2.0) | External HDD (USB 2.0) | Mouse (USB 1.0) |
| Normal | 276 | 201 | 210 | 263 |
| With Fix | 281 | 270 | 267 | 258 |
Facebook
Twitter
RSS
61 Comments
View All Comments
Mezcal - Tuesday, February 14, 2006 - link
Hello, I tested perfmon after reading your test. I own an Acer Aspire 5024 with a Turion 64 ML34 inside. So, I was wondering if this could cause me any battery problem. After testing Perfmon with % C3 time with USB wireless mini mouse, I can see a graph with mountains (between 60 and 100%) while the USB mouse is not plugged in and completely flat (0%) while plugged in. So, this may be the result of the problem you described? No?I didn't test the battery life with the USB mouse plugged in and without it 'cause I can't find any utility to test that. So, I can't say if it affects the battery life.
IntelUser2000 - Tuesday, February 14, 2006 - link
According to AT, it means Turion systems also have the same problem as the Centrinos in terms of battery life reduction when USB 2.0 devices are connected. Since % mean HOW OFTEN THE CPU IS IN LOW POWER C-STATE, 0% means its not going into low power states AT ALL, while 60-100% means its going into low power state 60-100% of the time.
NullSubroutine - Monday, February 13, 2006 - link
I am awaiting my new Dell Inspiron E1705 (2ghz Duo, 2GB 667mhz, 80GB SATA 7200, Ultrasharp 1920x1200, 7800GTX Go) I hope this issue has a better fix because it seemed the fix didnt work will with this system. I think the USB hub that is built into the system may be the cause of this, hopefully Anand can get the review of this system and see if he can fix. Personal request if anyone reads this, apply new artic silver on the cpu/gpu then see how much cooler it runs, and how much more you can overclock the gpu...pretty please...IntelUser2000 - Tuesday, February 14, 2006 - link
quasarsky - Tuesday, February 14, 2006 - link
weird. u say c4 is the 'sixth' power state. 0,1,2,3,4. sounds like it would be fifth. ???? am i missing something here?IntelUser2000 - Tuesday, February 14, 2006 - link
Anand said this:
For Pentium M
C0
C1
C2
C3
C4
Core Duo adds: deep C4
Coldfusion - Monday, February 13, 2006 - link
Or is it strictly a Windows issue?bobsmith1492 - Monday, February 13, 2006 - link
Wow.. so maybe this explains why my battery life is so different now than when my computer was new - I swear, when I first looked at it, it was saying 7 hours and I got like 5 when doing normal activities. With my mouse, though, it's more like 3-4... of course, it's a year older also. (P-M 1.7 Dothan)How can you tell whether or not a device is USB 2.0? I'm sure something in the device manager says, but I can't tell..
huges84 - Monday, February 13, 2006 - link
Why is it that the two Asus systems that are the same, except for motherboard and a slight difference in memory speed, showed that the Sonoma platform had better battery life than the Napa platform? I know it isn't much difference, but shouldn't the Napa be noticably ahead of Sonoma?Does the memory difference make that much of an impact? Or are the power consumption improvements in Napa pretty much only for when the processor is basically completely idle? If so then I don't think many people will see the extended battery life. Unless you like to leave your computer idle when it is running on battery. Maybe the improvements are also on the upper end and it is just the middle ground that didn't get improved. How high is CPU utilization in this test?
IntelUser2000 - Tuesday, February 14, 2006 - link
Well the difference is within margin of error. While W5F based on Core Duo gains less than W5A based on Pentium M, the difference is very little, less than 15 min.
Lenovo shows better results. T60 based on Core Duo always gets slightly better than T43 based on Pentium M, whether before or after, and T60 can support higher resolution, otherwise identical components.