I have two Boxes running Debian 7 with the following processors. Each Box has two of the same processors.

  1. Intel® Xeon® Processor E5-2620 (15M Cache, 2.00 GHz, 7.20 GT/s Intel® QPI)

    # of Cores 6

    # of Threads 12

  2. Intel® Xeon® Processor E5-2609 v2 (10M Cache, 2.50 GHz)

    # of Cores 4

    # of Threads 4

Now when running the following two commands on both servers - cat /proc/cpuinfo | grep processor and lscpu - I get that Box 1 has 0-23 and Box 2 has 0-8.

Is this expected given the above specifications and if so how does Debian arrive at these figures? I have read up on hyperthreading however it doesn't seem to explain the reason for arriving at these. Figures.

I am tempted to say Debian bases this on the #threads
so box

  1. 12 (#thread) X 2(#processors) = 24
  2. 4(#thread) X 2(#processors) = 8

But threads just show the number of concurrent pipes a multi-threading application have access to. I think over the years of development terminology of CPU,processors, sockets and cores have become convoluted.


This is due to the differences between the processor models.

You are correct in that Threads == number of concurrent threads, and is a composite of the core count, socket count and whether Hyperthreading is available on the particular CPU.

The main difference here is that the E5-2609 is a low-end CPU and doesn't have Hyperthreading available. The E5-2620 is the least expensive CPU in that line that has Hyperthreading.

So the 2609 is really just a 4-core CPU. You have two of them, so you have 8 physical cores.

The 2620 is a 6-core CPU with Hypethreading... so you have 12 "threads" comprised of 6 physical cores and 6 logical cores. With two CPUs, that gives you 12 physical cores and 24 threads.

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  • Thanks a lot it makes sense.You have cleared up several misconceptions i have had on the topic. – sqwale Oct 22 '14 at 14:50

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