Unbalanced timer interrupts under VMWare?

Ivan Voras ivoras at freebsd.org
Wed Dec 21 11:02:21 UTC 2011


I have a strange situation on a VMWare 5-hosted machine:

# vmstat -i
interrupt                          total       rate
irq1: atkbd0                          74          0
irq6: fdc0                            11          0
irq15: ata1                           17          0
irq18: em0                         42122          1
cpu0:timer                       2246291         54
irq256: mpt0                      141402          3
cpu1:timer                        280800          6
Total                            2710717         65

The cpu0 timer interrupt rate is 54 Hz and cpu1 rate is 6 Hz. The same 
is visible when monitoring the system in real time with "systat -vm".

This is a default FreeBSD 9 RC3 amd64 system, HZ is the default 100. 
Unless the tickless kernel project has advanced more than I think, this 
looks like a problem... so I looked elsewhere and it turns out I cannot 
get more than about 55 interrupts/s with the disk controller either.

Any ideas? I have another host running VMware 5 but only an 8-stable 
machine in it, which works fine. Does anyone else run 9.x on VMware 5?

The host is a Xeon X3360 CPU (4 cores, no HTT, 2.8 GHz).



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