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Comment by tgv | Hacker News Reader

My main problem was that our hosting company offers cheap Linux servers, but with a shared CPU that even doesn't support v2. We pay more now, but you could still run into that problem.

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It's likely this is a hypervisor misconfiguration. Either way, one has to wonder what kind of mitigations for cross-tenant leakage they are missing.

Or on purpose, because the CPUs with AVX are more expensive. Or historical: the hardware for this kind of service may have been old, and you can't tell people that if you buy today you get a processor with AVX, but tomorrow you may get one without. I haven't checked if they upgraded their low-cost options in a while.

You can try to execute POPCNT. If it does not fault, its presence is only hidden via CPUID.

Live migration support may be the reason why they stick to the baseline. That's most likely to be migratable across different CPU types. Although with a bit of effort, you can figure out what is support by your fleet and configure that into the hypervisors.

I'm skeptical that pre-SSE-4.2 etc. CPUs are economically viable for running customer workloads due to electricity costs.

Either it's a misconfiguration, or it's intentional (only providing a "bare-bones" machine for the lowest price level, even if the underlying hardware would support more)?

Isn't there a thermal cost to AVX instructions? Or, thinking of other reasons, if you're splitting up physical hardware into a "vCPU", it it possible that AVX doesn't map cleanly?

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