Linux Returns To Parallel CPU Microcode Updates To Reduce Cloud Disruption

Serial late microcode updates on large core count servers was slow with it being done one CPU at a time. In the change by an Intel engineer, he acknowledged "cloud customers have expressed discontent." So now it's being parallelized again while ensuring only one core is updated at a time, i.e. not the SMT sibling thread.
At least one of the cloud vendors seeking this serial/parallel CPU microcode change was Oracle. That change is now queued in tip.git as material waiting around until Linux 5.5 unless some urgency is determined to get it into 5.4 as a "fix" for the kernel.
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