KPTI + Retpoline Linux Benchmarking On Older Clarksfield / Penryn ThinkPads
Written by Michael Larabel in Software on 11 January 2018. Page 6 of 6. 35 Comments

The percentage loss from socket activity on the mitigated kernel was roughly the same between the three laptops.

But with the context switching benchmark via stress-ng, the Clarksfield and Penryn hardware was more noticeably impacted.

Likewise, with the System V message passing micro-benchmark, the older hardware saw a more significant drop in performance.

While lastly with the Apache web server benchmark, the percentage difference was about the same across the three tested Lenovo Linux systems.

In some benchmarks the older ThinkPads with pre-PCID processors did end up seeing a larger (percentage) loss, but besides Redis that was mostly isolated to micro-benchmarks like the stress-ng kernel tester. Going into the testing, frankly, I expected a larger performance loss with these around decade old Clarksfield and Penryn laptops relative to the Broadwell reference laptop. In simple CPU workloads like GraphicsMagick and FLAC audio encoding there remained little to no performance impact from the KPTI and Retpoline code mitigating Meltdown and Spectre, but as illustrated over the past week, with workloads having high I/O and poking the kernel the overhead is more noticeable.

Those wishing to dig into the raw numbers of these benchmarks can find all of the data via OpenBenchmarking.org.


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Michael Larabel is the principal author of Phoronix.com and founded the site in 2004 with a focus on enriching the Linux hardware experience. Michael has written more than 10,000 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 OpenBenchmarking.org automated benchmarking software. He can be followed via Twitter or contacted via MichaelLarabel.com.


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