[linux][performance] tools for monitoring

Reference:
https://netflixtechblog.com/linux-performance-analysis-in-60-000-milliseconds-accc10403c55

cmds:

$ uptime
$ dmesg | tail
$ vmstat -m (virtual memory statistics, slab memory info)
$ mpstat -P ALL (Report processors related statistics.)
$ pidstat (Report statistics for Linux tasks)
$ iostat -xz (Report Central Processing Unit (CPU) statistics and input/output statistics for devices and partitions.)
$ free -m (memory info)
$ top

https://serverfault.com/a/913089
$ systemctl start  sysstat sysstat-collect.timer sysstat-summary.timer
$ systemctl enable sysstat sysstat-collect.timer sysstat-summary.timer
$ sar -n DEV 1 (Collect, report, or save system activity information: )
$ sar -n TCP,ETCP 1