One Of The Reasons Why Linux 5.5 Can Be Running Slower
Written by Michael Larabel in Software on 29 December 2019. Page 3 of 3. 56 Comments

Fortunately, AppArmor can be easily toggled at boot-time for the Linux kernel. So without having to rebuild the kernel once more but simply running the latest Linux Git with "apparmor=0" as a kernel parameter, AppArmor was disabled. Using that to confirm AppArmor as the Linux 5.5 regression culprit.

Besides the AMD EPYC 7742 2P testing, disabling AppArmor to workaround the Linux 5.5 slowdown on the Intel Xeon Platinum 8280 server with Ubuntu was also successful.

While taking care of the Hackbench result, some of the workloads like Memcached and Parboil were among those still slower on Linux 5.5 Git master.

As time allows I am still investigating some of the other Linux 5.5 results that were also pointing to lower performance than with Linux 5.4. If you would like to show your support and to allow for more investigative testing, consider showing your support by making a PayPal tip or partaking in the Phoronix 2019 Holiday Special but at the very least to not view this website with any ad-blocker.

To be continued.

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Michael Larabel is the principal author of 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 automated benchmarking software. He can be followed via Twitter or contacted via

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