13-15 November 2018
America/Vancouver timezone

Runtime PM timer granularity issue

15 Nov 2018, 11:45
20m
Junior-Ballroom-AB (Sheraton Vancouver Wall Center)

Junior-Ballroom-AB

Sheraton Vancouver Wall Center

100

Speaker

Vincent Guittot (Linaro)

Description

Runtime PM allows drivers to automatically suspend devices that have not been used for a defined amount of time. This autosuspend feature is really efficient for handling bursts of activity on a device by optimizing the number of runtime PM suspend/resume calls. However, the runtime PM timers used for that are fully based on jiffies granularity which raises problems for some embedded ARM platforms that want to optimize their energy usage as much as possible. For example, the minimum timeout value on arm64 is between 4 and 8 ms.

The session will discuss the impact of switching runtime PM over to using hrtimers and a more fine graied time scale. It also will highlight the advantages and drawbacks of the changes relative to the current situation.

Primary author

Vincent Guittot (Linaro)

Presentation Materials

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