Re: Panic of 8-CURRENT in VMWare

Jeff Roberson wrote:
> 
> On Tue, 18 Mar 2008, Ivan Voras wrote:
> 
>> Ivan Voras wrote:
>>> Hi,
>>> I cannot boot a very recent build (minutes ago) of 8-CURRENT on 
>>> VMWare Server. Panic ("integer divide fault" - is this division by 
>>> zero?) is in sched_rr_interval().
>>>
>>> More info here:
>>> http://ivoras.sharanet.org/stuff/panic/
>>>
>>> It might be because I'm trying to run without WITNESS+INVARIANTS.
>>
>> No, building a GENERIC kernel doesn't change anything. It's also not a 
>> cvsup glitch - todays sources panic in exactly the same way.
>>
>>
> Can you tell me what the values of:
> 
> sysctl kern.sched.slice
> 
> and
> 
> sysctl kern.clockrate
> 
> are?

The machine doesn't finish booting the kernel (i.e. init isn't executed) 
and fetching sysctls apparently isn't supported by the kernel debugger 
(though it would be nice if it did work, at least for simple variables).

The only old kernel I have is 7.0RC1, and in it I can only access 
kern.clockrate, which is { hz=50, tick=20000, profhz=33, stathz=6 }.

Since you brought up the issue of clocks, I removed the tuning of 
kern.hz (it was present there practically forever) and the panic's gone. 
I use low values for kern.hz in VMWare to (noticably) reduce problems 
with clock drift and context switches, so it would be nice to not have 
the kernel panic with it :)

Apparently lowering kern.hz works upto about 75 - anything lower 
triggers the integer divide fault.