CPU cores and hyperthreaded

edited July 2014 in Pre Sales Questions
By 4 CPU machine : do you mean 4 physical cores?
Are your CPUs hyperthreaded?
Therefore for hyperthreaded CPUs, with a 4 CPU instance, the total number of hyperthreads available is 8?

Comments

  • You get exactly as many CPU cores as the plans offer. If you purchase a plan with 4 cores, your server will have 4 core visible. You would not see 8 cores in that case.
  • In that case are you offering one "hyperthread" as compute units when you refer to "one cpu core"?
    Can you share the make-model of the CPUs on your servers for more clarity?

  • AIUI, what they call a CPU is a logical processing unit. In older systems that would be just a physical CPU, today that may be a core (like on my Intel Q9400 quad core CPU) or on newer systems with multiple threads per core, a CPU would refer to a thread.

    So with todays systems your CPU count is sockets * cores per socket * threads per core.

    Under Linux run lscpu and it will show your topology (of course under QEMU it will show what QEMU has been assigned).

    So if you have 4 virtual CPU's in your VM, I guess the only real thing you'd want is that all those logical cpus come from at least the same socket (or maybe even core?)

    Andrew
  • I guess this does bring up the question of whether they oversubscribe at least CPU wise.

    If the host has 24 cpu's, do they limit the virtual cpu's allocated to 24 or would they allow 36, 48 etc expecting that people won't all be maxing out their cpu's?.

    Andrew
  • I don't think you'll ever find a node that is oversubscribed. Our benchmarks are leading the competition by almost 2-fold and we plan to keep it that way.
  • Good to hear!
  • Would be even better to hear something more quantified :)

    Do you have a policy on how many vCPUs are created for each physical core or thread?

    What's the max number of vCPUs you have for each physical core?

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