Task Manager might show 100% disk utilization on Windows 10 devices with Message Signaled Interrupt (MSI) mode enabled

by | Sep 10, 2017 | Microsoft Windows | 0 comments

Symptoms

Task Manager shows the disk to be at 100% utilization despite a light or no workload, and the system may experience lag or become unresponsive. In addition, the system event log contains numerous events with Event ID 129, which represent resets of the disk controller.

While device resets can be caused by a varying number of factors, we are aware of issues with some Advanced Host Controller Interface PCI-Express(AHCI PCIe) models that causes these symptoms in Windows 10 when running with the inbox StorAHCI.sys driver. Due to a firmware bug, the Solid-state drive (SSD) does not properly complete input/output when Message Signaled Interrupt (MSI) mode is enabled. As a result, the Windows storage stack attempts to reset the device after waiting on unresponsive reads or writes for a period of time.
MSI mode can be disabled for specific devices via the registry:
  1. Identify if you are running the inbox AHCI driver (StorAHCI.sys):
    1. Open a command prompt with administrator privileges. Then type the following command in the command prompt window and hit Enter: devmgmt.msc
    2. Under IDE ATA/ATAPI Controllers right-click on the AHCI controller node and select Properties. This node is usually called “Standard SATA AHCI Controller.”
    3. Navigate to the driver tab and click Driver Details.
    4. If you see “StorAHCI.sys” in the list, you are running the inbox driver.
  2. Disable MSI for the controller in the registry:
    1. In the same properties window opened in step 1.2, navigate to the Details tab and select Device instance pathfrom the Property drop-down menu. Note this path.
    2. Open the registry editor by typing regedit in the previously opened command prompt.
    3. Navigate to: HKEY_LOCAL_MACHINE\System\CurrentControlSet\Enum\PCI\ <AHCI Controller>\Device Parameters\Interrupt Management\MessageSignaledInterruptProperties, where <AHCI Controller> refers to the device instance path you noted in step 2.1.
    4. Change the value of the MSISupported key from “1” to “0”.
    5. If you don’t know which controller your boot device is attached to, repeat steps 2.1 through 2.4 for all AHCI controllers found under 1.2.
  3. Reboot the machine.

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