Reducing the performance impact of 'Meltdown' CVE fixes for OpenStack guests with "PCID" CPU feature flag

Solution Unverified - Updated -


Fixes for Meltdown security vulnerability variants can result in some performance slowdown for certain workloads, given the nature of those vulnerabilities and their fixes. This is well documented in the following related article:

Is it possible to reduce the performance impact 'Meltdown' fixes have on OpenStack Platform guests? Yes, it is — by ensuring the presence of a particular CPU feature flag called 'PCID' (Process Context ID) within the guest. More details on that in the following sections.


  • Red Hat OpenStack Platform.
  • x86_64 architecture.

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