Debian vs. Ubuntu vs. CentOS vs. openSUSE vs. Clear Linux Post-Meltdown Performance

With Linux distributions being patched since last week's Meltdown and Spectre disclosure, here are benchmarks on some of the prominent distributions looking at their performance impact since being patched. Tested from an Intel Core i7 8700K system was CentOS, Clear Linux, Debian, openSUSE, and Ubuntu.

This article is offering a first-look at the performance of various Linux distributions before and after being patched to address the recent CPU vulnerability disclosures. Most Linux distributions have been shipping KPTI/KAISER support while others are still working on Spectre mitigation with the Retpoline patches, which have yet to be merged to the mainline Linux kernel or the related GCC compiler patches. Hopefully the Retpoline work will settle down in the weeks ahead. A rough recap for these distributions comes down to:

Canonical on 9 January pushed Meltdown (KPTI) patches to the kernels of their supported Ubuntu releases. Spectre/Retpoline patches are still to come.

Debian has patched their Stretch, Jessie, and Wheezy kernels with KPTI for Spectre mitigation but Meltdown is still a work-in-progress.

CentOS has released updated CentoS 6 and 7 kernels based upon RHEL 6/7 fixes. CentOS/RHEL has also published update CPU microcode from Intel.

Clear Linux 20240 added KPTI and Retpoline support for mitigating Meltdown and Spectre. The Retpoline support does include GCC 7.2 that is patched with the necessary changes too. This is some of the most complete protection currently available for Linux distributions with not many shipping Retpoline patches yet let alone a patched compiler with neither the Linux kernel nor GCC seeing support mainlined yet.

SUSE and openSUSE distributions are patched since last week with KPTI/KAISER for their respective supported kernels as well as issuing new AMD/Intel CPU microcode. Retpoline support has yet to land.

These five Linux distributions were tested on the Intel Core i7 8700K (Coffee Lake) system with the UHD Graphics, ASUS PRIME Z370-A motherboard, 2 x 8GB DDR4-3000 memory, and Samsung 950 PRO 256GB NVMe SSD. All of these benchmarks were facilitated using the Phoronix Test Suite.