[vm-bhyve] Windows 2012 and 2016 servers guests would not stop

[Paul Vixie]

Victor Sudakov wrote on 2019-04-22 19:43:
...
>> And the implementation is pretty brutal:
>> # 'vm stopall'
>> # stop all bhyve instances
>> # note this will also stop instances not started by vm-bhyve
>> #
>> core::stopall(){
>>      local _pids=$(pgrep -f 'bhyve:')
>>
>>      echo "Shutting down all bhyve virtual machines"
>>      killall bhyve
>>      sleep 1
>>      killall bhyve
>>      wait_for_pids ${_pids}
>> }

yow.

>>
>> I wonder what the effect of the second kill is,
>> that seems odd.
> 
> Indeed.

the first killall will cause each client OS to see a soft shutdown 
signal. the sleep 1 gives them some time to flush their buffers. the 
second killall says, time's up, just stop.

i think this is worse than brutal, it's wrong. consider freebsd's own 
work flow when trying to comply with the first soft shutdown it got:

https://github.com/freebsd/freebsd/blob/master/sbin/reboot/reboot.c#L220

this has bitten me more than once, because using "pageins" as a proxy 
for "my server processes are busy trying to synchronize their user mode 
state" is inaccurate. i think _any_ continuing I/O should be reason to 
wait the full 60 seconds.

and so i think the "sleep 1" above should be a "sleep 65".

> What is needed in vm-bhyve is the feature that if ACPI does not stop the
> guest for a predefined period of time, the guest is powered off.

i agree with this.

-- 
P Vixie