The Speculative Execution Impact For A 4-Core POWER9 Blackbird Desktop
Written by Michael Larabel in Processors on 12 June 2019. Page 4 of 4. 13 Comments

Overall there tends to be a generally small but noticeable performance hit from these mitigations but not nearly as significant as the Intel performance costs.

If looking at the geometric mean, the kernel-only protections performed basically the same as the unmitigated results at a high level. The default kernel+user protections meanwhile yielded about an 8% hit to the performance, much lower than the ~18% we're usually seeing on Intel CPUs. Coming up soon I'll have an Intel/AMD/POWER9/ARM mitigation impact comparison but for this article just wanted to get some numbers out there now on this POWER9 4-core / 16-thread system for those wondering about its status.

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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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