Ubuntu 13.04 vs. Ubuntu 20.04 Development Performance Comparison Without Mitigations

Last week I posted benchmarks looking at seven years of Ubuntu Linux performance in re-testing the releases of Ubuntu 13.04 through Ubuntu 19.10 stable and even the latest Ubuntu 20.04 LTS daily development image. A question that came up was how much better that performance would have been without any CPU vulnerability mitigations in place for Ubuntu 20.04... Well, here's that answer.

In this article are the Ubuntu 13.04, Ubuntu 19.10, and Ubuntu 20.04 daily benchmark results from that earlier article plus an additional run now after re-testing Ubuntu 20.04 when the kernel was booted with "mitigations=off" for getting an idea of the performance lost due to the various in-kernel mitigations over the past nearly three years.

The same Core i7 2700K system was used throughout with the hardware differences just coming down to how each Ubuntu Linux release exposed the system information.



Disabling the mitigations helped in the various workloads like I/O that were impacted by the likes of Spectre and Meltdown.
But in some cases, the performance still isn't at the Ubuntu 13.04 performance levels due to regressions or other functionality added that lowered the performance over the years.


With some of the tests when disabling mitigations it was able to put the Ubuntu 20.04 LTS performance well ahead of where this Intel Sandy Bridge started out right after launch with Ubuntu 13.04.









It was an interesting look. If summing up all the tests by taking the geometric mean of all the benchmarks in full that ran across all four tested configurations, here is that metric:

Disabling the mitigations on Ubuntu 20.04 daily boosted the Intel Core i7 performance by 6.6%. That puts the Ubuntu 20.04 performance in turn at 14% higher than Ubuntu 13.04. More benchmark results via the complete Ubuntu 13.04 through 20.04 benchmark comparison.