It is totally fine for a Linux System to use the Swap, after all why do we have it if we do not want to use it?
But sometimes you get the feeling that some process or another are running slower than you imagined and you have that feeling that this guy is slowing down in swap.
Well there are a few tools out there that can help and tell you that, or you do it like me, get really bored and fine tune a onliner that lists everything that is currently in swap.
grep -i swap /proc/*/status 2>/dev/null | awk -F: '{print $1, $3}' | sed 's/\/proc\///;s/\/status//' | while read pid swap; do swap_clean=$(echo $swap | sed 's/[^0-9]//g'); if [[ -n "$swap_clean" && "$swap_clean" -gt 0 ]]; then user=$(ps -o user= -p $pid 2>/dev/null); cmdline=$(cat /proc/$pid/cmdline 2>/dev/null | tr '\0' ' ' | cut -c 1-100); [ -z "$cmdline" ] && cmdline="[Keine Info verfügbar oder Kernel-Prozess]"; echo -e "USER: $user\tPID: $pid\tSWAP: ${swap_clean}kB\tCOMMAND: $cmdline"; fi; done | sort -k3 -n
Sorry, this is not really THE SOLUTION as you do need to have sed and awk on the system, which is not everywhere the case, but it is yet another fast way of finding out.