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logical CPU count: Doesn't match with what is showed in histogram

Hash
Beginner
557 Views

let's say logical CPU count has 16 and histogram starts with 0-16 which means 17. could someone explain?

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9 Replies
PrasanthD_intel
Moderator
540 Views

Hi Hashim,


What was the histogram you were mentioning? and how did you built that?

Could you please let us know the output of /proc/cpuinfo and lscpu?


Regards

Prasanth


Hash
Beginner
529 Views

here is the output of lscpu:

 

Architecture: x86_64
CPU op-mode(s): 32-bit, 64-bit
Byte Order: Little Endian
CPU(s): 16
On-line CPU(s) list: 0-15
Thread(s) per core: 2
Core(s) per socket: 8
Socket(s): 1
NUMA node(s): 1
Vendor ID: GenuineIntel
CPU family: 6
Model: 158
Model name: Intel(R) Core(TM) i9-9900K CPU @ 3.60GHz
Stepping: 12
CPU MHz: 4699.902
CPU max MHz: 5000.0000
CPU min MHz: 800.0000
BogoMIPS: 7200.00
Virtualization: VT-x
L1d cache: 32K
L1i cache: 32K
L2 cache: 256K
L3 cache: 16384K
NUMA node0 CPU(s): 0-15

 

 

In Hotspots by CPU Utilization, I see total logical CPUs as 16 but the histogram shows from 0-16.

Hash_0-1614781270326.png

 

one more clarification I need is if my application is using only 0 and 1 CPUs during the application run (as shown in the histogram), showing other CPUs poor/ok/Ideal means that they are being used by other applications by other user applications?

 

PrasanthD_intel
Moderator
480 Views

Hi Hashim,

 

In the Effective CPU Utilization Histogram of Vtune, the X-axis doesn't represent the CPU count. It represents simultaneously utilized logical CPU's which means if it shows 0 means the program is idle and if it shows 16 means that the program is utilizing all the 16 CPUs simultaneously.

In your case, the histogram shows that only one CPU is utilized at a time and it doesn't mean that CPU-1 is being utilized. It may also be the case that the program ran on different CPUs at different times but ran only on one CPU at a given time.

 

Let us know if you need any further explanation.

 

Regards

Prasanth

Hash
Beginner
473 Views

Thank you for the response. could you please refer me to any online help to better understand these details.

PrasanthD_intel
Moderator
463 Views

Hi Hashim,


I am moving this thread to the Analyzers forum(Analyzers - Intel Community), a dedicated forum Vtune Profiler Issues, where you can get better support.

We will get back to you soon.


Regards

Prasanth


ArunJ_Intel
Moderator
397 Views

Hey Hash




The below link provides more info on Effective CPU Utilization Histogram


https://software.intel.com/content/www/us/en/develop/documentation/vtune-help/top/reference/user-int...


 

Thanks

Arun Jose


ArunJ_Intel
Moderator
342 Views

Hi Hash,


Is there anything else you need help with regarding this issue. If not please let us know if we could stop monitoring this space.


Thanks

Arun


Hash
Beginner
327 Views

Thank you for your support. At this time you can close this issue.

ArunJ_Intel
Moderator
300 Views

Hi Hash

 

Thanks for the confirmation. If you need any additional information, please submit a new question as this thread will no longer be monitored.

 

 

Arun Jose


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