The Performance Cost Of Spectre / Meltdown / Foreshadow Mitigations On Linux 4.19

Written by Michael Larabel in Software on 30 August 2018. Page 5 of 5. 29 Comments

With the OSBench test of file creation speed, the Intel Xeon performance out-of-the-box was 84~87% the speed of an unmitigated kernel while the EPYC systems were at 91~94%.

With the thread creation test, there was also a measurable difference between the Intel and AMD processors.

Or in the time to launch programs and create processes, there was a smaller but still evident difference with the default Linux 4.19 kernel against the unmitigated configuration.

That's where things stand today with the out-of-the-box performance cost of these CPU vulnerability mitigations with the Linux 4.19 kernel. Keep in mind if your system(s) are exposed to untrusted users/code, particularly in VMs, additional steps like l1tf=full may be needed where you may end up disabling SMT/HT or always enforce the L1 cache flushing rather than the conditional behavior, which will further lower the performance of the systems. More of those impacts for this L1TF/Foreshadow mitigation can be found in this earlier article.

Similar tests with desktop CPUs and more desktop focused workloads will be carried out on Linux 4.19 if there us sufficient interest. You can show your support for our Linux benchmarking by joining Phoronix Premium or making a PayPal tip to help cover the time involved, hardware expenses, electrical costs, etc, or at the very least to please not view this site with any ad-blockers.

For those interested in the raw numbers of this benchmark comparison, they can be found via, our "cloud" component to the Phoronix Test Suite.

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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 TwitterLinkedIn,> or contacted via