Total CPU usage - multicore system

Question

I am using xen and with xen top I get the total CPU usage in percentage:

      NAME  STATE   CPU(sec) CPU(%)     MEM(k) MEM(%)  MAXMEM(k) MAXMEM(%) VCPUS NETS NETTX(k) NETRX(k) VBDS   VBD_OO   VBD_RD   VBD_WR  VBD_RSECT  VBD_WSECT SSID

      VM1 -----r      25724  299.4    3025244   12.0   20975616      83.4    12    1 14970253 27308358    1        3   146585    92257   10835706    9976308    0

As you can see from above I see the CPU usage is 299 %, but how I can get the total CPU usage from a VM ? Top doesn't show me the total usage.

Jay jargot · Accepted Answer · 2016-05-01 23:50:34Z

5

We usually see 100% cpu per core. I guess there are at least 3 cores/cpus.

try this to count cores:

grep processor /proc/cpuinfo | wc -l

299% is the total cpu usage.

sar and mpstat are often used to display cpu usage of a system. Check that systat package is installed and display total cpu usage with:

$ mpstat 1 1
Linux 2.6.32-5-amd64 (debian)   05/01/2016      _x86_64_        (8 CPU)

07:48:51 PM  CPU    %usr   %nice    %sys %iowait    %irq   %soft  %steal  %guest   %idle
07:48:52 PM  all    0.12    0.00    0.50    0.00    0.00    0.00    0.00    0.00   99.38
Average:     all    0.12    0.00    0.50    0.00    0.00    0.00    0.00    0.00   99.38

If you agree that CPU utilisation is (100 - %IDLE):

$ mpstat 1 1 | awk '/^Average/ {print 100-$NF,"%"}'
0.52 %

edited May 1, 2016 at 23:50

answered Apr 30, 2016 at 10:24

Jay jargot

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4 Comments

user3580316 Over a year ago

I want to see the CPU usage in total across all of the cores.

Jay jargot Over a year ago

@user3580316 I think that 299% is the total cpu usage (I do not know xen). top and sar are often used.

user3580316 Over a year ago

thanks. But it doesn't show the summary of the total cpu usage, only for usage for each cpu core.

DanieleO Over a year ago

@Jayjargot Sorry to re-open the question, is it always correct to use as standard 100-idle (In my case I have a system monitoring written as sh script in a huge server. 2xE5-2667 v4 8core)?

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