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vy32
Asked: 2018-02-10 16:59:42 +0800 CST

How many cores are in Amazon's m4.16xlarge node?

  • 772

Amazon's marketing materials claim that the m4.16xlarge node has 64 vCPU.

When I look at /proc/cpuinfo on the system, however, I get the following information:

  • 64 CPUs (CPU 0 .. 63)
  • cpu cores: 16
  • Processor type: Intel(R) Xenon(R) CPU E5-2686 v4 @ 2.30Ghz

So this makes no sense to me. This means that I have 64 CPUs with 16 cores each, or a total of 1024 cores.

However, online documentation for the Intel E5-2686 v6 claims that it has 36 cores and hyperthreading, for 72 virtual cores.

What's going on? How many cores are there?

amazon-ec2

1 Answers

  1. Best Answer

    /proc/cpuinfo reports each hyperthread as a CPU.

    The E5-2686 v4 processor has 18 cores and 36 hyperthreads.

    You should have access to 16 cores (presumably called core id 0 through 15) on physical processor 0 and another 16 cores (again, core id 0 through 15) on physical processor 1. The output makes it look like 16 cores, but it's actually 16 cores on each, with the identifier reused, total cores = 32.

    So, there are 2 CPU sockets, 16 cores/32 hyperthreads each, so you have 32 total cores, and 64 hyperthreads/vCPUs.

    The remaining 4 cores/8 vCPU on the host machine would be allocated to other instances.

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