CPU/GPU Usage Between NVIDIA & AMD Linux Drivers
Written by Michael Larabel in Hardware on 29 October 2015 at 10:39 AM EDT. 6 Comments
Following the 4K AMD/NVIDIA High-End GPU Comparison On SteamOS Linux and 22-Way Comparison Of NVIDIA/AMD Graphics Cards On SteamOS For Steam Linux Gaming articles, a few Phoronix readers were inquiring about the CPU and GPU utilization metrics during testing.

So I started work on some follow-up tests to look at the CPU/GPU utilization during testing to try to answer that question. The Phoronix Test Suite is able to do so by simply setting MONITOR=cpu.usage,gpu.usage as an environment variable prior to running any benchmarks (or see phoronix-test-suite system-sensors or MONITOR=all for the other system sensors supported through Phodevi - The Phoronix Device Interface).

While I started to run some CPU/GPU tests, for saving time I limited it to the demanding Metro 2033 Redux and Metro Last Light Redux games on Ubuntu Linux.

The tests on this Ubuntu 15.04 Linux 3.19 installation seem to have an oddity with the P-State driver flip-flopping between powersave and performance governors as the default at boot time, but for this P-State driver, as past Phoronix benchmarks have shown this doesn't lead to much of a performance change.

The tests ended up being a bit of a let down though. While there's been GPU utilization monitoring in the Phoronix Test Suite for years with AMD Catalyst support, it seems a recent driver update has broken that interface. With Catalyst 15.9, I no longer see a way to be able to read the global GPU utilization as a percentage... The NVIDIA binary driver though continues work fine with their stable interfaces for years.

You can see Metro Last Light Redux is using more of the GPU than Metro 2033 Redux, which was the first of the two tests run.

When it comes to the overall CPU utilization when using the proprietary drivers and testing four graphics cards from each brand, there wasn't a huge difference.

You can see all of these system monitoring results via this OpenBenchmarking.org result file, but long story short, it doesn't bring anything new to light. The Radeon GPU usage data would have made it more interesting, but alas, I can't seem to find a way to tap it on Catalyst 15.9. Before asking for open-source usage numbers, with the Radeon/Nouveau DRM drivers there also doesn't seem to be a way to read the global GPU utilization as a percent.

For those playing around with the Phoronix Test Suite, be sure to try whatever benchmarks suit your fancy while setting MONITOR=all. There are also various modules to complement the Phoronix Test Suite's data, such as the recent Linux perf subsystem performance counter reporting module in PTS 6.0-Hammerfest.
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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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