Testing The Intel "Workload Hints" Capability Of Linux 5.11

Many different workloads were tested. Of all the tests carried out, pretty much the only observation was seeing single-threaded workloads run slower under the obvious idle and battery life modes. All of the benchmarks run in full can be found via this OpenBenchmarking.org result file.

When taking the geometric mean of all the benchmark results, in terms of the raw performance the default "none" behavior didn't yield any difference compared to sustained/bursty/semi_active. When running in the battery life and idle modes the performance was about 16% lower overall.

When looking at the CPU power consumption values over the entire span of benchmarking, the battery life and idle runs had a 12 Watt average compared to the other workload hints leading to a 14~15 Watt average. The peak power consumption was much lower with the battery life and idle hints. (Yes, these are values straight from Intel RAPL where in some cases as high as 50 Watts being reported.) Nearly the entire time with the battery life / idle workload hints the CPU package power consumption was at or below 25 Watts while with the other hints was generally 30 Watts or less.

The idle/battery_life workload hints led to the Dell XPS 13 9310 running around 6 degrees cooler on average while the peak CPU temperature reported was at just 83 degrees compared to 100 degrees in the most demanding benchmarks with the other workload hints.

So for those curious about the Intel INT340X workload hints support coming to Linux 5.11, hopefully this initial testing was helpful. The impact will obviously vary based on the SoC / device but at least from this preliminary testing it seems the battery_life/idle hints are most useful if wanting to help keep your system running cooler or extending your battery life. We'll see if any Linux desktops or other user-space solutions begin making use of the new interface for automatically setting an appropriate workload hint for users automatically.