Multi-threaded process on a multi-vCPU system

From: Hameed, Amir <Amir.Hameed_at_xerox.com>
Date: Mon, 31 Aug 2020 14:38:31 +0000
Message-ID: <DM6PR11MB34837EF5507898754C2CD341F4510_at_DM6PR11MB3483.namprd11.prod.outlook.com>

Hi,
On a multi-processor system, do all threads of a multi-threaded process run on the same CPU or do they utilize all available CPUs? Output from the PIDSTAT utility on a 2-vCPU VM running RHEL7 shows that multiple threads from a JAVA process are running on different vCPUS (a snippet is pasted below). Is this the right interpretation of the output?

pidstat -t -u -p 10512 15

10:31:41 AM   UID      TGID       TID    %usr %system  %guest    %CPU   CPU  Command
10:31:56 AM 52951     10512         -  100.00    4.67    0.00  100.00     1  java
10:31:56 AM 52951         -     10512    0.00    0.00    0.00    0.00     1  |__java
10:31:56 AM 52951         -     10513    0.00    0.00    0.00    0.00     0  |__java
10:31:56 AM 52951         -     10517    0.07    0.00    0.00    0.07     0  |__java
10:31:56 AM 52951         -     10518    0.00    0.00    0.00    0.00     0  |__java
10:31:56 AM 52951         -     10519    0.07    0.07    0.00    0.13     0  |__java
10:31:56 AM 52951         -     10522    0.07    0.00    0.00    0.07     1  |__java
10:31:56 AM 52951         -     10523    0.00    0.00    0.00    0.00     1  |__java
10:31:56 AM 52951         -     10524    0.07    0.00    0.00    0.07     1  |__java
10:31:56 AM 52951         -     10525    0.27    0.07    0.00    0.33     1  |__java
10:31:56 AM 52951         -     10526    0.27    0.20    0.00    0.47     1  |__java
10:31:56 AM 52951         -     10527    0.07    0.07    0.00    0.13     0  |__java
10:31:56 AM 52951         -     10529   15.73    0.00    0.00   15.73     0  |__java
10:31:56 AM 52951         -     10530   15.53    0.07    0.00   15.60     1  |__java
10:31:56 AM 52951         -     10557    0.00    0.00    0.00    0.00     0  |__java
10:31:56 AM 52951         -     10558    1.60    0.00    0.00    1.60     1  |__java
10:31:56 AM 52951         -     10559    0.00    0.00    0.00    0.00     0  |__java
10:31:56 AM 52951         -     10560    0.00    0.00    0.00    0.00     1  |__java
10:31:56 AM 52951         -     10561    0.00    0.00    0.00    0.00     0  |__java
10:31:56 AM 52951         -     10562    0.00    0.00    0.00    0.00     1  |__java
10:31:56 AM 52951         -     10563    0.00    0.00    0.00    0.00     0  |__java
10:31:56 AM 52951         -     10564    0.00    0.00    0.00    0.00     1  |__java
10:31:56 AM 52951         -     10565    0.00    0.00    0.00    0.00     0  |__java

...
Thanks,
Amir

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Received on Mon Aug 31 2020 - 16:38:31 CEST