Intel Continues Working On Significant GPU Power Optimization For The Linux Kernel
Written by Michael Larabel in Intel on 17 March 2020 at 08:08 AM EDT. 3 Comments
INTEL --
A set of kernel patches to Intel's graphics driver helps improve the GPU power consumption to the extent of on Chrome OS seeing about 45 minutes extra battery life and several percent under the likes of Ubuntu Linux.

Back at the end of 2018 I wrote about Intel looking at another graphics driver power optimization with the work led by Ankit Navik of Intel's open-source team. It's that patch series that nearly two years later continues to be improved upon for extending the battery life of Linux-based Intel laptops.

Navik posted the seventh revision to those patches on Monday for context-aware user-agnostic EU/slice/sub-slice control.On a Geminilake platform running Chrome OS he found the battery life to improve by about 45 minutes with ~14% power benefit when watching YouTube content or engaging in WebGL demos. When gaming with Unity 3D, the performance benefit was still a respectable 6%.

Or on the likes of Ubuntu, with various graphics tests it was in the 2~5% range, however, he hadn't done any YouTube/video tests on that front. But long story short, these patches at a minimum can improve the Intel Linux laptop battery life by several percent.

Here's how the savings are achieved:
Current GPU configuration code for i915 does not allow us to change EU/Slice/Sub-slice configuration dynamically. Its done only once while context is created.

While particular graphics application is running, if we examine the command requests from user space, we observe that command density is not consistent. It means there is scope to change the graphics configuration dynamically even while context is running actively. This patch series proposes the solution to find the active pending load for all active context at given time and based on that, dynamically perform graphics configuration for each context.

The patches come in at just over 200 lines of code. It's too late already for seeing it for the upcoming Linux 5.7 merge window with the DRM-Next cut-off already upon us but hopefully we can see these Intel power saving optimizations ready for Linux 5.8 this summer.
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Michael Larabel is the principal author of Phoronix.com and founded the site in 2004 with a focus on enriching the Linux hardware experience. Michael has written more than 20,000 articles covering the state of Linux hardware support, Linux performance, graphics drivers, and other topics. Michael is also the lead developer of the Phoronix Test Suite, Phoromatic, and OpenBenchmarking.org automated benchmarking software. He can be followed via Twitter or contacted via MichaelLarabel.com.

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