Linux 3.15 Should Suspend & Resume Much Faster

The Linux 3.15 kernel will feature a large number of ACPI and power management updates when its merge window opens in the days ahead.

Rafael J. Wysocki published a list this week of all the changes he has queued up for the Linux 3.15 kernel when it comes to new work. Given that the merge window will soon be open, Rafael isn't planning to accept any new work to be added to this Linux 3.15 pull.

Among the many items that will be found for the ACPI/PM pull request, a few of the changes that caught our attention were numerous ACPICA updates, CPUfreq now being supported for 64-bit ARM (ARMv8/AArch64) drivers, support for setting latency tolerance values for LPSS devices handling Latency Tolerance Reporting, asynchronous threads for more PM / sleep phases, and various other fixes and improvements.

Visible to users with the Linux 3.15 kernel should be reduced time for system suspend and resuming, thanks to the enabling of more asynchronous threads. Chuansheng Liu had written, "This patch series are for enabling the asynchronous threads for the phases resume_noirq, resume_early, suspend_noirq and suspend_late. Just like commit 5af84b82701a and 97df8c12995, with async threads it will reduce the system suspending and resuming time significantly. With these patches, in my test platform, it saved 80% time in resume_noirq phase."

More details on the Linux 3.15 ACPI / PM changes can be found via this mailing list message.