Host Memory and CPU Troubleshooting

• Install and enable sysstat
  • systemctl enable --now sysstat
  • systemctl status sysstat
• Enable sysstat data collection
  • sudo vim /etc/default/sysstat
  • ENABLED="true"
• Check sysstat configuration
  • sudo cat /etc/cron.d/sysstat
• Understanding uptime and load averages for 1, 5, and 15 mns.
  • uptime
  • Just uptime, no averages
  • uptime -s
  • Pretty output
  • uptime -p
  • Check uptime in seconds and idle time, respectively.
  • cat /proc/uptime
  • Learn about the proc filesystem, the pseudo-filesystem which provides an interface to kernel data structures.
  • man procfs
  • List CPUs
  • lscpu
  • How many cpus?
  • lscpu | grep '^CPU(s)'
• Monitoring high CPU with mpstat and sar -u
  • mpstat
  • Run every 1 second for 60 seconds on all processors.
  • mpstat 1 60
  • Run every 1 second for 60 seconds on 0 processor.
  • mpstat -P 0 1 60
  • Check historical load information for all or one processor, with the System Activity Reporter.
  • sar -u / sar-u -P 0
  • Identify CPU hog using Top
  • top
• Viewing RAM and Swap usage
  • free -h
  • cat /proc/meminfo
  • View collected memory information
  • sar -r
  • Sort top by memory usage f, Arrow Down TO MEM
  • top
    • f to open fields
    • arrow down from CPU to MEM
    • s for select
    • q for quit