Benchmarks Of JCC Erratum: A New Intel CPU Bug With Performance Implications On Skylake Through Cascade Lake
Written by Michael Larabel in Processors on 12 November 2019. Page 9 of 9. 40 Comments

Python and PHP Performance were again common tests impacted by the microcode update.

The Apache web server is another one of the cases where the patched assembler was yielding a performance hit, but hopefully Intel's software wizards will be able to figure that out and improve upon their assembler patch in the near future.

That's where things stand right now with regards to the Intel JCC erratum bug. The microcode update does cause a hit of generally up to a couple percent but as shown in this article there are some outliers where in select real-world workloads the impact is greater. The patched GNU Assembler update was able to successfully offset the performance losses in many of the tests, but in some cases not entirely recovered and other tests the strange behavior of regressing the performance. The patched GNU Assembler is available already on Intel's Clear Linux while we'll be reporting when the patch(es) are upstreamed and work their way into the relevant other Linux distributions, etc.

Gaming benchmarks and other tests of the JCC erratum will be on Phoronix shortly.

Update: JCC Erratum microcode update tests for gaming performance are now published.

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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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