questions on cores v/s threads, Domain PKG and Domain PP0

[Vihan Pandey]

Dear all,

I had the following questions :

1)I have a board with 2 sockets each with 1, Intel(R) Xeon(R) CPU E5-2650 0 @ 2.00GHz which as the documentation here :

http://ark.intel.com/products/64590/Intel-Xeon-Processor-E5-2650-20M-Cache-2_00-GHz-8_00-GTs-Intel-QPI

has 8 cores, each of which can do 2 parallel threads i.e 16 threads per CPU per socket i.e 32 parallel threads in total.

Even when I run htop, I see 32 parallel threads :


  1  [||        9.1%]    9  [|         0.6%]     17 [          0.0%]    25 [          0.0%]
  2  [||        4.4%]    10 [          0.0%]     18 [          0.0%]    26 [          0.0%]
  3  [          0.0%]    11 [          0.0%]     19 [||        4.5%]    27 [          0.0%]
  4  [          0.0%]    12 [          0.0%]     20 [          0.0%]    28 [          0.0%]
  5  [|         0.6%]    13 [          0.0%]     21 [|         0.6%]    29 [||||||||100.0%]
  6  [|         7.0%]    14 [          0.0%]     22 [          0.0%]    30 [          0.0%]
  7  [|         1.9%]    15 [          0.0%]     23 [|         6.3%]    31 [          0.0%]
  8  [||       11.4%]    16 [          0.0%]     24 [          0.0%]    32 [          0.0%]
  Mem[|||||||||||||||||||     8130/128899MB]     Tasks: 199, 733 thr; 2 running
  Swp[|                          33/61033MB]     Load average: 1.12 1.06 0.79
                                                 Uptime: 27 days, 17:04:12


Therefore, when I run :

# likwid-powermeter -t

it shows me :

$ likwid-powermeter -t
--------------------------------------------------------------------------------
CPU name:    Intel(R) Xeon(R) CPU E5-2650 0 @ 2.00GHz
CPU type:    Intel Xeon SandyBridge EN/EP processor
CPU clock:    2.00 GHz
--------------------------------------------------------------------------------
--------------------------------------------------------------------------------
Current core temperatures:
Socket 0 Core 0: 45 C
Socket 0 Core 16: 45 C
Socket 0 Core 1: 48 C
Socket 0 Core 17: 48 C
Socket 0 Core 2: 41 C
Socket 0 Core 18: 41 C
Socket 0 Core 3: 46 C
Socket 0 Core 19: 46 C
Socket 0 Core 4: 45 C
Socket 0 Core 20: 45 C
Socket 0 Core 5: 46 C
Socket 0 Core 21: 46 C
Socket 0 Core 6: 42 C
Socket 0 Core 22: 42 C
Socket 0 Core 7: 45 C
Socket 0 Core 23: 45 C
Socket 1 Core 8: 60 C
Socket 1 Core 24: 60 C
Socket 1 Core 9: 57 C
Socket 1 Core 25: 57 C
Socket 1 Core 10: 63 C
Socket 1 Core 26: 63 C
Socket 1 Core 11: 59 C
Socket 1 Core 27: 59 C
Socket 1 Core 12: 64 C
Socket 1 Core 28: 64 C
Socket 1 Core 13: 63 C
Socket 1 Core 29: 63 C
Socket 1 Core 14: 62 C
Socket 1 Core 30: 62 C
Socket 1 Core 15: 59 C
Socket 1 Core 31: 59 C

Why does it say 16 ``cores’’ per socket i,e 32 ``cores”?

2)I wanted a clearer understanding of what Domain PKG and Domain PP0 measure in terms of energy and power. Specifically when running :

$ likwid-powermeter -s 1s
--------------------------------------------------------------------------------
CPU name:    Intel(R) Xeon(R) CPU E5-2650 0 @ 2.00GHz
CPU type:    Intel Xeon SandyBridge EN/EP processor
CPU clock:    2.00 GHz
--------------------------------------------------------------------------------
--------------------------------------------------------------------------------
Runtime: 1.00063 s
Measure for socket 0 on CPU 0
Domain PKG:
Energy consumed: 18.2948 Joules
Power consumed: 18.2833 Watt
Domain PP0:
Energy consumed: 5.11462 Joules
Power consumed: 5.11143 Watt
Domain DRAM:
Energy consumed: 0 Joules
Power consumed: 0 Watt

Measure for socket 1 on CPU 8
Domain PKG:
Energy consumed: 28.9223 Joules
Power consumed: 28.9042 Watt
Domain PP0:
Energy consumed: 15.4035 Joules
Power consumed: 15.3939 Watt
Domain DRAM:
Energy consumed: 0 Joules
Power consumed: 0 Watt
--------------------------------------------------------------------------------

Please can someone point me to some detailed online documentation on Domain PKG and Domain PP0 or even explain it as a reply to this?

3)Lastly, I remember reading that Domain DRAM readings are only supported by server side and not workstation/PC CPU's is that right? Moreover, will Domain DRAM specifically measure the energy and power consumed by the RAM chip(s) on the board?

Sorry for the laziness :P

Cheers!

- vihan

[Thomas Röhl]

Hi Vihan,

1)I have a board with 2 sockets each with 1, Intel(R) Xeon(R) CPU E5-2650 0 @ 2.00GHz which as the documentation here :

http://ark.intel.com/products/64590/Intel-Xeon-Processor-E5-2650-20M-Cache-2_00-GHz-8_00-GTs-Intel-QPI

has 8 cores, each of which can do 2 parallel threads i.e 16 threads per CPU per socket i.e 32 parallel threads in total.

Even when I run htop, I see 32 parallel threads :

 

I think we are clear, that the counts alone are valid but the "naming" is not obvious. A core commonly means the physical processing unit while hardware threads are virtual processing units. So, in fact, we should change the "Core" to "HWThread" or something similar. The output loop for the temperatures is really simple, maybe I should put some more intelligence in it.

This paper defines the PKG domain as whole socket and PP0 as only the CPU cores. See 2.1 in http://www.eecs.berkeley.edu/Pubs/TechRpts/2012/EECS-2012-168.pdf.

I haven't seen a list with component to domain relations, so no further details on that.

3)Lastly, I remember reading that Domain DRAM readings are only supported by server side and not workstation/PC CPU's is that right? Moreover, will Domain DRAM specifically measure the energy and power consumed by the RAM chip(s) on the board?

There are also desktop systems which support the reading of DRAM energy (e.g. my current workstation with Intel i7-4770).
According to the above paper, it is the sum of all DRAM modules' energy.

Greetings,
Thomas

[Vihan Pandey]

Thanks a million for this Thomas!

Cheers!

- vihan
 

Greetings,
Thomas