Using renice and taskset to manage process priority and CPU affinity with Linux OEL 6.4

Using renice and taskset to manage process priority and CPU affinity with Linux OEL 6.4

Table of Contents

Overview

Process NICE priority values range from -20 to 19. ( see top NI column )
NI is the nice value, which is a user-space concept. PR is the process’s actual priority, as viewed by the Linux kernel.

For normal processes, the kernel priority is simply +20 from the nice value. Thus a process with the neutral nice value of zero has a kernel priority of 20. This offset-by-20 is done so that a process with a nice value of -20, the highest priority nice value, receives a kernel priority of zero. Lower numeric values equal higher scheduling priority.
For realtime processes, the kernel priority is the process’s real-time priority, but the PR column will simply print RT.

A process with the nice value of -20 is considered to be on top of the priority. And a process with nice value of 19 is considered to be low on the priority list.Using renice and taskset to manager a Linux process

 

Using renice and taskset to manage a Linux process

Display CPU Affinity for LGWR process and change CPU affinity to CPU 5

$ ps -elf | egrep 'NI|ora_lgwr' |  grep -v grep
F S UID        PID  PPID  C PRI  NI ADDR SZ WCHAN  STIME TTY          TIME CMD
0 S oracle    5825     1  0  60 -20 - 394456 semtim 13:25 ?       00:00:24 ora_lgwr_grac41

$ taskset -pc 5 5825
pid 5825's current affinity list: 0-7
pid 5825's new affinity list: 5

Monitor CPU affinity with top 
# top -H -p 5825 [  --> Press f --> Press j to add CPU affinity col ]
  PID USER      PR  NI  VIRT  RES  SHR S %CPU %MEM    TIME+  P COMMAND                                                              
 5825 oracle    20   0 1540m  32m  28m S  0.0  0.8   0:24.62 5 oracle             
--> P shows the CPU affinity which is 5 !

Compile a load program and and set affinity to CPU 5 during program start 
$ cc sq.c -o sq -lm
$ taskset -c 5 sq
$ sp
PID: 15949

  PID USER      PR  NI  VIRT  RES  SHR S %CPU %MEM    TIME+  P COMMAND                                                              
15949 oracle    20   0  6544  312  244 R 73.7  0.0   1:50.17 5 sq                                                                   
 5825 oracle    20   0 1540m  32m  28m S  0.0  0.8   0:25.10 5 oracle     

Increase the priority of a process and monitor this process
# renice -15 15949

# top -H -p 15949 [  --> Press f --> Press j to add CPU affinity col ]
Cpu(s):  9.5%us,  3.1%sy,  0.0%ni, 87.2%id,  0.1%wa,  0.0%hi,  0.2%si,  0.0%st

  PID USER      PR  NI  VIRT  RES  SHR S %CPU %MEM    TIME+  P COMMAND                                                              
15949 oracle     5 -15  6544  308  244 R 70.9  0.0  38:43.36 5 sq                                                                   
 5825 oracle    20   0 1540m  33m  29m S  0.0  0.8   1:20.49 5 oracle
0 (0)
Article Rating (No Votes)
Rate this article
Attachments
There are no attachments for this article.
Comments
There are no comments for this article. Be the first to post a comment.
Full Name
Email Address
Security Code Security Code
Related Articles RSS Feed
Do you Know These 5 Use of V$session View ?
Viewed 5196 times since Thu, Jun 21, 2018
Tilix: Advanced Tiling Terminal Emulator for Power Users
Viewed 1278 times since Thu, Apr 18, 2019
Linux – delete the LUN and remove traces from OS
Viewed 866 times since Tue, May 22, 2018
OpenSSL: Check SSL Certificate Expiration Date and More
Viewed 586 times since Mon, Feb 18, 2019
Setting up encrypted tunnel using stunnel
Viewed 416 times since Fri, Sep 28, 2018
Open SSL Encrypt & Decrypt Files With Password Using OpenSSL
Viewed 715 times since Mon, Feb 18, 2019
RHEL7: Configure automatic updates.
Viewed 412 times since Wed, Oct 17, 2018
stunnel Howto A Guide to create SSL access to a HTTP-only webserver with stunnel
Viewed 464 times since Fri, Sep 28, 2018
Top 25 Best Linux Performance Monitoring and Debugging Tools
Viewed 3107 times since Sun, Sep 30, 2018
LVM: Managing snapshots
Viewed 682 times since Sat, Jun 2, 2018