Xenial test kernel at http://people.canonical.com/~rtg/nvme-google/
-- You received this bug notification because you are a member of Kernel Packages, which is subscribed to linux in Ubuntu. https://bugs.launchpad.net/bugs/1637565 Title: nvme: improve performance for virtual Google NVMe devices Status in linux package in Ubuntu: In Progress Status in linux source package in Xenial: In Progress Status in linux source package in Yakkety: Fix Committed Status in linux source package in Zesty: In Progress Bug description: This change provides a mechanism to reduce the number of MMIO doorbell writes for the NVMe driver. When running in a virtualized environment like QEMU, the cost of an MMIO is quite hefy here. The main idea for the patch is provide the device two memory location locations: 1) to store the doorbell values so they can be lookup without the doorbell MMIO write 2) to store an event index. I believe the doorbell value is obvious, the event index not so much. Similar to the virtio specificaiton, the virtual device can tell the driver (guest OS) not to write MMIO unless you are writing past this value. FYI: doorbell values are written by the nvme driver (guest OS) and the event index is written by the virtual device (host OS). The patch implements a new admin command that will communicate where these two memory locations reside. If the command fails, the nvme driver will work as before without any optimizations. To manage notifications about this bug go to: https://bugs.launchpad.net/ubuntu/+source/linux/+bug/1637565/+subscriptions -- Mailing list: https://launchpad.net/~kernel-packages Post to : kernel-packages@lists.launchpad.net Unsubscribe : https://launchpad.net/~kernel-packages More help : https://help.launchpad.net/ListHelp
