1

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.

2

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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