Friday, March 27, 2020

Emulator 30.0.6 Canary, Windows performance

Emulator 30.0.6 is now available in the Canary and Dev channels. Changes:
  • Upgraded protobuf verison to 3.11.4
  • Added experimental car data replay feature for when running Android Auto Embedded system images to the car data page in the extended controls. The feature is flagged off and is called CarVhalReplay. To enable:
    • Launch the emulator from command line with -feature CarVhalReplay
    • Or, add "CarVhalReplay = on" to ~/.android/advancedFeatures.ini
    • More details
  • Fixed kernel version parsing issue when running aarch64 guest kernels.
  • Vulkan
    • Worked around issue that occurs on Windows NVIDIA GPUs when creating/destroying VkPipelineLayouts in multiple threads.
  • Improved support (fixes, performance improvements) for host-side video codecs. Requires a future Android R system image.

Windows performance

We've noticed that the emulator has been running much slower on some Windows 10 systems than others, while some versions of Windows 8.x and below seem unaffected. The issue seems to be due to a recently introduced mitigation for the Foreshadow (L1TF) security vulnerability: https://support.microsoft.com/en-us/help/4073119/protect-against-speculative-execution-side-channel-vulnerabilities-in

Disabling the L1TF mitigation via

reg add "HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\Control\Session Manager\Memory Management" /v FeatureSettingsOverride /t REG_DWORD /d 3 /f
reg add "HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\Control\Session Manager\Memory Management" /v FeatureSettingsOverrideMask /t REG_DWORD /d 3 /f


(and then rebooting) will restore performance to its previous state. However, we don't recommend this if you are using the emulator to run arbitrary untrusted code.