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From: Ivan Voras <ivoras@freebsd.org>
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Subject: Re: Unbalanced timer interrupts under VMWare?
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On 21.12.2011. 14:48, Maxim Dounin wrote:
> Hello!
>
> On Wed, Dec 21, 2011 at 12:02:04PM +0100, Ivan Voras wrote:

>> Unless the tickless kernel project has advanced more than I think,
>
> It is, actually.  Many thanks to mav@ for his amazing work.
>
> $ sysctl kern.eventtimer.periodic
> kern.eventtimer.periodic: 0
>
> $ vmstat -i | grep timer
> cpu0:timer                      72769640         47

Ah, great! I missed that commit :) Thanks mav!

> And down to 37 i/s as seen in "systat -vm".  Idle virtual machine
> now takes 2 times less CPU on my laptop as seen from the host.
>
>> 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.
>
> Happily goes to 6k i/s here (though it's under VirtualBox and
> a bit old -current, not 9.0).

Yes, it looks like it's not related to the tickless mode, the disk IO is 
slow even when kern.eventtimer.periodic=1. Something else is broken.