[Xen-users] CPU activity: top and xm top

[Igor Chubin <igor@xxxxxxx>]

Hello all,


I feel that my question is silly, 
but have no explanation of this fact.

I run xm top and see that my CPU is utilized for 20%.


    $ xm top
    xentop - 11:02:34 Xen 3.0.3-1
    1 domains: 1 running, 0 blocked, 0 paused, 0 crashed, 0 dying, 0
    shutdown
    Mem: 2096380k total, 222848k used, 1873532k free CPUs: 2 @ 2133MHz
    NAME STATE CPU(sec) CPU(%) MEM(k) MEM(%) MAXMEM(k) MAXMEM(%) VCPUS NETS 
NETTX(k) NETRX(k) VBDS VBD_OO VBD_RD VBD_WR SSID
    Domain-0 -----r 123 22.0   196608 9.4    no limit  n/a       2     24   395 
     1081     0    0      0      0      0


After that I run top and see that the CPU load is ~3%


    top - 11:06:12 up 12 min, 2 users, load average: 0.07, 0.03, 0.01
    Tasks: 184 total, 1 running, 183 sleeping, 0 stopped, 0 zombie
    Cpu(s): 0.4%us, 1.4%sy, 0.0%ni, 97.7%id, 0.5%wa, 0.0%hi, 0.0%si, 0.1%st
    Mem: 196756k total, 105660k used, 91096k free, 5136k buffers
    Swap: 3903672k total, 0k used, 3903672k free, 36084k cached


I have run "top" and "xm top" simultaneously also.
The same.

I have only domain 0 running. No U-domains at all.

    $ sudo xm list
    Name     ID Mem(MiB) VCPUs State  Time(s)
    Domain-0 0  192      2     r----- 184.0

How does xm top calculate cpu activity?
Is there any way to access low level information that xm top uses in
its calculations?





Question #2.

How can I gather information about system activity in the Xen domain 0?
In regular systems, not in Xen, I have used to use sar for this.
But under Xen sar can't show many interesting parameters,
e.g. interrupts activity.



Thank you!

-- 
WBR, i.m.chubin


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