Problem #2 - Disabling a USB device doesn't work

If we now know that this problem should affect both Napa (Core Duo) and Sonoma (Pentium M) platforms, why is it that the results that we've seen to date don't support that theory?  While we can only comment on tests that we've run ourselves, we did run into some issues with the ASUS W5F/W5A notebooks, which are quickly becoming popular Napa/Sonoma test platforms. 

The reason that the two ASUS notebooks are nice to use is because they are virtually identical systems, one simply uses a Sonoma motherboard with a Pentium M CPU while the other uses a Napa board with a Core Duo CPU.  In the end, it provides an excellent level playing field for comparing Core Duo to its predecessor. 

The problem is that both ASUS notebooks feature an integrated USB 2.0 camera, which we originally didn't expect to be a problem because we left it disabled and without its drivers installed.  After all, if a device doesn't have its driver initialized, it shouldn't be impacting our test results, correct?  But let's look at the Microsoft KB article a little closer. Under the cause of the problem, the article states that "Windows XP SP2 installs a USB 2.0 driver that initializes any connected USB device."  It sounds like simply connecting a USB 2.0 device, even if you don't load the drivers for it, would still trigger the bug.  But does that mean if you disable the device, the asynchronous scheduler is still running?  There's only one way to find out, so we ran the Mobile Mark test again, this time on a Lenovo T60 with no integrated USB 2.0 devices. We then connected a USB 2.0 device to it, but did not install a driver, as well as tried disabling the device:

 Lenovo T60 Nothing Connected  USB 2.0 Device Connected, No Driver Installed  USB Device Disabled
Reader 2002SE Battery Life in Minutes 286 242 235

With a USB 2.0 device (an external TV tuner) connected, but no driver installed, the battery life on our T60 dropped from 286 minutes down to 242, a reduction of 15.3%.  Disabling the device had no effect either, as we recorded a battery life of 235 minutes.  These findings are particularly important because both ASUS notebooks, the Sonoma and the Napa, feature an integrated USB 2.0 camera.  Even without the drivers loaded, short of ripping the camera out of the system, these two notebooks are terrible reference points for the USB power draw issue as both of them exhibit the issue without even plugging in any external devices! 

To confirm, we looked at C3 time once more on both platforms:

The ASUS notebooks never enter C3 or lower power states, even with no external devices connected

Just as we suspected, the CPUs aren't allowed into their lower power states due to the integrated USB 2.0 camera. 

To further confirm, we applied the workaround documented in the Microsoft KB article.  With no external devices connected to either system, their battery life jumped by approximately another hour:

Reader 2002SE Battery Life in Minutes Nothing Connected  Nothing Connected (MS Fix Applied)
ASUS W5F (Napa/Core Duo) 219 264
ASUS W5A (Sonoma/Pentium M) 204 273

While this means that our battery life tests from our Core Duo notebook article are significantly lower than they should be (we'll be providing a follow-up to that article in the near future), it also means that neither ASUS notebook should be used in pinpointing the cause or effects of this USB problem. 

Adding an external USB 2.0 device to either ASUS notebook does result in an additional drop in battery life, but the initial damage is done by the integrated camera that you can't unplug.  To truly isolate this problem, we'll need two notebooks that don't have any integrated USB 2.0 devices, which is why we turned to the Lenovo Thinkpad T43 and T60. 

Problem #1 - Perfmon is Inaccurate Problem #3 - The fix doesn't always work
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  • krwilsonn - Wednesday, February 15, 2006 - link

    I just read their new article and apparently they were tipped off by some "insider" about the problem and then went ahead and "discovered" and published it. That is what it says at the end of their article, anyway. Their forum thread that is linked has some comments from an editor or someone that are also interesting. I'm sure everyone is checking it out but for those that haven't you should for the sheer humor of it.
  • mino - Tuesday, February 14, 2006 - link

    1.) Installed new hp6220 custom configured an hour ago.
    Platform i915G - Sonoma

    Provided Perfmon detects C3 correctly (showing curve around 98% at idle) this system may not bee affected.

    I've installed HP's "System Enhancements Disk" package, so some workaround by HP may have been included. (the regfix is not present)

    However I have no way to prove Perfmon is correct.

    2.) nx6125 I've upgraded from home to Pro last week so it is HP install just a little sripped one

    the system spend around 96% of its time at idle in C1, seems wierd to me. No time is spent in C3 also. Maybe somne HP stuff keep the CPU busy.

    Both systems are used with Bluetooth mouse via an integrated adapter.
  • mino - Tuesday, February 14, 2006 - link

    Just now I observed on nx6125 that the moment Intellimouse Explorer for Bluetooth goes into power save mode (after ~1 minute of inactivity) Turion goes from 96% in C1 to 96% in C2.
    Strange as it may seem nothing like this happens on Sonoma platform. I sense ATI SB400 does have something say about it.

    Another thing is that the moment CPU starts using C2 intensively, the idle power consumption goes from ~15.6W to 13.2W which is pretty serious amount of power wasted.

    Anand, I suggest you do not waste your time by testing battery life when you revisit this issue, to prove assumptions you may use Perfmon's Battery Drain counter.

    HMM, funny is, the nc6220 does not show the battery counter present in Perfmon.
  • mino - Tuesday, February 14, 2006 - link


    sripped == stripped

  • artifex - Tuesday, February 14, 2006 - link

    as soon as you get an MBP in for testing :)
  • zsouthboy - Tuesday, February 14, 2006 - link

    Not that its as big a deal for desktops, but mine seems to be doing the same thing when my USB 2.0 mouse/kb is plugged in...

  • krwilsonn - Tuesday, February 14, 2006 - link

    Are you being serious??
  • kmmatney - Tuesday, February 14, 2006 - link

    Yeah, I've noticed my Prescott's been running a little hot as well. Damn USB 2.0!
  • blwest - Tuesday, February 14, 2006 - link

    Yay, yet another "feature". If you run Microsoft Winders, we gurantee shorter battery life.
  • dualathlon - Tuesday, February 14, 2006 - link

    Hi, i own an dell inspiron 9300, pen M 760, geforce 6800go. When i enable that registry key, i experience heavy pointer delay when playing Counter Strike Source. I tried both logitech mx510 (wired) and logitech mx900 (bluetooth wireless, paired with dell internal BT and logitech hub as well).

    I see no delay in office apps, FYI. I haven't test battery life with that key though.

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