There are many ways of monitoring system process and load average including uptime which shows system status about how long the system has been running, number of users together with load averages:
$ uptime 07:13:53 up 8 days, 19 min, 1 user, load average: 1.98, 2.15, 2.21
The numbers are read from left to right, and the output above means that:
- load average over the last 1 minute is 1.98
- load average over the last 5 minutes is 2.15
- load average over the last 15 minutes is 2.21
High load averages imply that a system is overloaded; many processes are waiting for CPU time.
We will uncover this in the next section in relation to the number of CPU cores. Additionally, we can as well use other well-known tools such as top and glances which display a real-time state of a running Linux system, plus many other tools:
Top Command
$ top
Display Running Linux Processes
top - 12:51:42 up 2:11, 1 user, load average: 1.22, 1.12, 1.26
Tasks: 243 total, 1 running, 242 sleeping, 0 stopped, 0 zombie
%Cpu(s): 17.4 us, 2.9 sy, 0.3 ni, 74.8 id, 4.6 wa, 0.0 hi, 0.0 si, 0.0 st
KiB Mem : 8069036 total, 388060 free, 4381184 used, 3299792 buff/cache
KiB Swap: 3906556 total, 3901876 free, 4680 used. 2807464 avail Mem
PID USER PR NI VIRT RES SHR S %CPU %MEM TIME+ COMMAND
6265 serverconfig 20 0 1244348 170680 83616 S 13.3 2.1 6:47.72 Headset
2301 serverconfig 9 -11 640332 13344 9932 S 6.7 0.2 2:18.96 pulseaudio
2459 serverconfig 20 0 1707692 315628 62992 S 6.7 3.9 6:55.45 cinnamon
2957 serverconfig 20 0 2644644 1.035g 137968 S 6.7 13.5 50:11.13 firefox
3208 serverconfig 20 0 507060 52136 33152 S 6.7 0.6 0:04.34 gnome-terminal-
3272 serverconfig 20 0 1521380 391324 178348 S 6.7 4.8 6:21.01 chrome
6220 serverconfig 20 0 1595392 106964 76836 S 6.7 1.3 3:31.94 Headset
1 root 20 0 120056 6204 3964 S 0.0 0.1 0:01.83 systemd
2 root 20 0 0 0 0 S 0.0 0.0 0:00.00 kthreadd
3 root 20 0 0 0 0 S 0.0 0.0 0:00.10 ksoftirqd/0
5 root 0 -20 0 0 0 S 0.0 0.0 0:00.00 kworker/0:0H
....
Glances Tool
$ glances
Glances – Linux System Monitoring Tool
serverconfig (LinuxMint 18 64bit / Linux 4.4.0-21-generic) Uptime: 2:16:06
CPU 16.4% nice: 0.1% LOAD 4-core MEM 60.5% active: 4.90G SWAP 0.1%
user: 10.2% irq: 0.0% 1 min: 1.20 total: 7.70G inactive: 2.07G total: 3.73G
system: 3.4% iowait: 2.7% 5 min: 1.16 used: 4.66G buffers: 242M used: 4.57M
idle: 83.6% steal: 0.0% 15 min: 1.24 free: 3.04G cached: 2.58G free: 3.72G
NETWORK Rx/s Tx/s TASKS 253 (883 thr), 1 run, 252 slp, 0 oth sorted automatically by cpu_percent, flat view
enp1s0 525Kb 31Kb
lo 2Kb 2Kb CPU% MEM% VIRT RES PID USER NI S TIME+ IOR/s IOW/s Command
wlp2s0 0b 0b 14.6 13.3 2.53G 1.03G 2957 serverconfig 0 S 51:49.10 0 40K /usr/lib/firefox/firefox
7.4 2.2 1.16G 176M 6265 serverconfig 0 S 7:08.18 0 0 /usr/lib/Headset/Headset --type=renderer --no-sandbox --primordial-pipe-token=879B36514C6BEDB183D3E4142774D1DF --lan
DISK I/O R/s W/s 4.9 3.9 1.63G 310M 2459 serverconfig 0 R 7:12.18 0 0 cinnamon --replace
ram0 0 0 4.2 0.2 625M 13.0M 2301 serverconfig -11 S 2:29.72 0 0 /usr/bin/pulseaudio --start --log-target=syslog
ram1 0 0 4.2 1.3 1.52G 105M 6220 serverconfig 0 S 3:42.64 0 0 /usr/lib/Headset/Headset
ram10 0 0 2.9 0.8 409M 66.7M 6240 serverconfig 0 S 2:40.44 0 0 /usr/lib/Headset/Headset --type=gpu-process --no-sandbox --supports-dual-gpus=false --gpu-driver-bug-workarounds=7,2
ram11 0 0 2.9 1.8 531M 142M 1690 root 0 S 6:03.79 0 0 /usr/lib/xorg/Xorg :0 -audit 0 -auth /var/lib/mdm/:0.Xauth -nolisten tcp vt8
ram12 0 0 2.6 0.3 79.3M 23.8M 9651 serverconfig 0 R 0:00.71 0 0 /usr/bin/python3 /usr/bin/glances
ram13 0 0 1.6 4.8 1.45G 382M 3272 serverconfig 0 S 6:25.30 0 4K /opt/google/chrome/chrome
...
The load averages shown by these tools is read /proc/loadavg file, which you can view using the cat command as below:
$ cat /proc/loadavg 2.48 1.69 1.42 5/889 10570
Understanding System Average Load in Relation Number of CPUs
We can’t possibly explain system load or system performance without shedding light on the impact of the number of CPU cores on performance.
Multi-processor Vs Multi-core
- Multi-processor – is where two or more physical CPU’s are integrated into a single computer system.
- Multi-core processor – is a single physical CPU which has at least two or more separate cores (or what we can also refer to as processing units) that work in parallel. Meaning a dual-core has 2 two processing units, a quad-core has 4 processing units and so on.
Furthermore, there is also a processor technology that was first introduced by Intel to improve parallel computing, referred to as hyperthreading.
Under hyperthreading, a single physical CPU core appears as two logical CPUs core to an operating system (but in reality, there is one physical hardware component).
Note that a single CPU core can only carry out one task at a time, thus technologies such as multiple CPUs/processors, multi-core CPUs and hyper-threading were brought to life.
With more than one CPU, several programs can be executed simultaneously. Present-day Intel CPUs use a combination of both multiple cores and hyper-threading technology.
To find the number of processing units available on a system, we may use the nproc or lscpu commands as follows:
$ nproc 4 OR lscpu
Another way to find the number of processing units using grep command as shown.
$ grep 'model name' /proc/cpuinfo | wc -l 4
Now, to further understand system load, we will take a few assumptions. Let’s say we have load averages below:
23:16:49 up 10:49, 5 user, load average: 1.00, 0.40, 3.35
On a single core system this would mean:
- The CPU was fully (100%) utilized on average; 1 processes was running on the CPU (1.00) over the last 1 minute.
- The CPU was idle by 60% on average; no processes were waiting for CPU time (0.40) over the last 5 minutes.
- The CPU was overloaded by 235% on average; 2.35 processes were waiting for CPU time (3.35) over the last 15 minutes.
On a dual-core system this would mean:
- The one CPU was 100% idle on average, one CPU was being used; no processes were waiting for CPU time(1.00) over the last 1 minute.
- The CPUs were idle by 160% on average; no processes were waiting for CPU time. (0.40) over the last 5 minutes.
- The CPUs were overloaded by 135% on average; 1.35 processes were waiting for CPU time. (3.35) over the last 15 minutes.
