21st Revision Of Patches For Getting Linux To Shutdown Devices Asynchronously

Being worked on for over two years has been the latest attempt for async device shutdown support for Linux for getting Linux systems -- especially servers with lots of hardware like many NVMe drives -- to shutdown faster. That work is now up to its 21st version as it works toward hopefully making it to the mainline kernel in the not too distant future. Red Hat's David Jeffery sent out the v21 patches on Wednesday to be able to shutdown devices asynchronously. The set of nine patches allow for the kernel to shutdown devices asynchronously as well as allowing unrelated async devices to be shutdown in parallel. Currently with the patches, devices need to explicitly opt-in to indicate they can be shutdown asynchronously. The impact of this async device shutdown support can be quite staggering as outlined by David Jeffery in the patch cover letter: "This can dramatically reduce system shutdown/reboot time on systems that have multiple devices that take many seconds to shut down (like certain NVMe drives). On one system tested, the shutdown time went from 11 minutes without this patch to 55 seconds with the patch. And on another system from 80 seconds to 11." The v21 patches are out for review on the Linux kernel mailing list and hopefully it won't be too much longer before this work finally crosses the finish line of the mainline kernel.