Sar -r (memory)

sar -r --human

09:38:01 PM kbmemfree   kbavail kbmemused  %memused kbbuffers  kbcached  kbcommit   %commit  kbactive   kbinact   kbdirty
09:39:01 PM    122.1G    478.5G    381.5G     75.8%    385.4M    348.8G     25.4G      5.0%     39.7G    330.0G     96.2M
09:40:01 PM    118.7G    478.5G    384.9G     76.4%    385.5M    352.1G     25.4G      5.0%     39.8G    333.2G    406.1M
09:41:01 PM    116.1G    478.4G    387.4G     76.9%    385.6M    354.6G     25.4G      5.0%     39.9G    335.7G    259.2M

Activities

1. Emptying the buffers cache: free -h && sync && echo 3 > /proc/sys/vm/drop_caches && free -h
2. Use fio with direct=0 to fill up your cache.

See also

• free command
• systemd-cgtop

https://unix.stackexchange.com/questions/87908/how-do-you-empty-the-buffers-and-cache-on-a-linux-system