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From Nux! <>
Subject Performance considerations related to Intel Meltdown on KVM CPU types
Date Mon, 08 Jan 2018 15:11:07 GMT

Just stumbled upon this

"ensure KVM guest CPU model you choose has the "pcid" feature, otherwise guests will suffer
terrible performance from the Meltdown fixes. This means using a named Haswell, Broadwell
or Skylake based model or host passthrough"

This means whoever is running with the KVM default CPU (like I do) as opposed to specific
ones or host passthrough needs to change this in order to avoid bad performance once the new
mitigating kernel is installed.

Bad news is older Xeons do not support this, check if "invpcid" flag shows up in /proc/cpuinfo
(you might see "pcid", that one is not enough).

Sent from the Delta quadrant using Borg technology!


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