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Comment by systemvoltage | Hacker News Reader

Virtualization over head is about 3-5% in my benchmarks in the past (on amd64, not not in ARM though).

it's 3-5% plus whatever mitigations cost

Many (though not all) of those mitigations remain important even for single-tenant remote servers, lest you get your keys or other secrets exfiltrated.

Which parts of a default install of which linux distro are remotely exploitable via spectre?

Not to be forgotten: per-core shared tenancy. I'd love to be proven wrong, but I doubt AWS allocates a full core for every non-burstable Arm "vCPU" sold.

Google does, this was a real sticking point for me when I was evaluating cloud options, at the time GCP was the only provider allocating (and affining) CPU cores to tennants

It was my understanding Amazon does in fact do this for most instance types, it's why the amount of RAM and other resources scales with CPU core count.

There are exceptions though in the very small "burstable" etc instances, like the micro etc.

EDIT: Seems I am wrong.

"Each vCPU is a thread of a CPU core, except for T2 instances and instances powered by AWS Graviton2 processors."

From: https://docs.aws.amazon.com/AWSEC2/latest/UserGuide/instance...

The exception for Graviton here is because every ARM vCPU is a full core, whereas an Intel/AMD vCPU is one hyperthread (i.e. half a core). They're not saying Graviton2 cores are shared. For Intel/AMD, you always get allocated both hyperthreads on a dedicated core; that's why hyperthreaded families start at 2 vCPUs. Only the "T" families feature shared cores.

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