I have a strange problem inside my Xen DomU.
Inside my domU, I have a tool running (lookbusy) that generates a
certain amount of cpu load.
Let's say, I generate 50% of CPU load on 1 core.
When I check the cpu load with top, I get something strange.
Here's the output from top:
top - 11:36:06 up 52 min, 1 user, load average: 0.54, 0.52, 0.46
Tasks: 68 total, 2 running, 66 sleeping, 0 stopped, 0 zombie
Cpu0 : 0.0%us, 0.0%sy, 0.0%ni, 99.8%id, 0.0%wa, 0.0%hi, 0.0%si,
Cpu1 : 34.0%us, 0.2%sy, 0.0%ni, 65.8%id, 0.0%wa, 0.0%hi, 0.0%si,
Mem: 262468k total, 32896k used, 229572k free, 0k buffers
Swap: 0k total, 0k used, 0k free, 10092k cached
PID USER PR NI VIRT RES SHR S %CPU %MEM TIME+ COMMAND
1384 root 20 0 1800 492 384 R 52 0.2 26:11.09 lookbusy
So, inside the detailed list, I see a CPU load of 52% (which is indeed
more or less what I expect),
but at the summary on the top of the output, I see the CPU1 is 65.8%
idle or thus only 34.2% loaded.
If I look with xen top from Domain-0, I see more or less 50%.
I also tried some other tools:
1) with ps: I see the 52% load
2) with vmstat: I get the 34.2% load
Is there anyone who has an idea what could cause this difference?
Which tool should I believe?
Here is my configuration:
hypervisor: Xen 3.4.0
Domain 0: 2.6.26-2-xen-686 image from Lenny distribution
Domain U: minimal version of a 2.6.26-kernel for xen domU (lenny).
Hardware: 4 cores in total, in the example described above, I had 1 cpu
core pinned for Domain-0 and 2 cpu cores pinned for the DomU.
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