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:

The first vertical line (orange) indicates the system going into stand-by, and the second vertical line (green) indicates the system coming out of stand-by. Once the system wakes up, it eventually initializes the asynchronous scheduler again and the CPU is no longer able to enter its lower power states.

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
Problem #2 - Disabling a USB device doesn't work Final Words
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  • Eris23007 - Monday, February 13, 2006 - link

    P.S. That's why you read more than just the intro and conclusion pages before asking questions.

    "RTFM"
    Reply
  • DigitalFreak - Monday, February 13, 2006 - link

    Ha! Reply
  • Eris23007 - Monday, February 13, 2006 - link

    The USB hard drive they tested with had its own power supply. The "USB Drive" was a flash device (USB bus powered), while the "External HDD" was:

    quote:

    Vantec NexStar 2 External 3.5" Hard Drive Enclosure (USB 2.0)

    Note that this device is entirely externally powered



    Reply
  • UNCjigga - Monday, February 13, 2006 - link

    I will have to do some testing on my notebook with the 'workaround' fix installed. I could have sworn that around the time I installed SP2 on my lappy the battery life suffered, but this was about 6-12 months after I got it so I just figured the battery was getting old. Reply
  • Ionizer86 - Monday, February 13, 2006 - link

    Wow, this is getting interesting. I'm surprised that this bug affects 915 based systems too. I wonder if this could be a broader issue that may affect intel 855 systems or AMD-based computers with chipsets from other vendors. I suppose I could do some playing around Reply
  • Ionizer86 - Monday, February 13, 2006 - link

    No edit button... (accidental post before completion).
    I could test this out on my 855 based laptop if only I had Perfmon and the special plugin :)
    Reply
  • Ionizer86 - Tuesday, February 14, 2006 - link

    Specs: Thinkpad R50e, Pentium M 1.5 on i855GME.

    I booted into Windows normal mode as cleanly as possible and ran Perfmon. The CPU was usually in C2 ~60% of the time and C3 ~35% of the time, for a total of ~95% in C2 or C3. Upon plugging in any of my USB stuff (an external hard disk, a Sandisk Cruzer mini, or even my IBM mouse), I'd get 95% in C2 and 0% in C3. Maybe my mouse is a USB 2.0 mouse; not sure.

    Battery draw goes from about 11.7W to 12.5W when I plug in my mouse.

    By adding the registry key, I no longer have the issue with the Cruzer or my external hard disk, but the problem with the mouse remains.

    Looks like MSFT has quite a problem at hand.
    Reply
  • Accord99 - Tuesday, February 14, 2006 - link

    0.8W, maybe its the power draw of the mouse itself? Reply
  • johnsonx - Monday, February 13, 2006 - link

    Adding to what Jason said, you only need the 'secret' plugin for Core Duo processors. The C3 state counter that Perfmon already has works fine on older platforms.
    Reply
  • IntelUser2000 - Tuesday, February 14, 2006 - link

    quote:

    Adding to what Jason said, you only need the 'secret' plugin for Core Duo processors. The C3 state counter that Perfmon already has works fine on older platforms.


    Not just Core Duo, but: "As you can probably guess, Perfmon is inaccurate in this case. While Perfmon does a fine job of monitoring C3 states for older processors, it fails to handle properly the CPUs we're most interested in: the Pentium M and Core Duo."
    Reply

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