[Users] Can host hooks be used to implement the following policy to avoid "boot storm"?

[Itamar Heim]

On 05/26/2013 01:43 PM, lofyer wrote:
> 于 2013/5/26 18:36, lofyer 写道:
>> 于 2013/5/26 15:41, Itamar Heim 写道:
>>> On 05/26/2013 09:59 AM, Roy Golan wrote:
>>>> On 05/24/2013 03:22 PM, Itamar Heim wrote:
>>>>> On 05/23/2013 04:23 PM, lofyer wrote:
>>>>>> Can host hooks be used to implement the following policy to avoid
>>>>>> "boot
>>>>>> storm"?
>>>>>>
>>>>>> 1.count and sort VMs awaiting for boot.
>>>>>> 2.If the count is less than or equal to, for example 5, then boot all
>>>>>> VMs and exit the script.
>>>>>> 3.Otherwise, boot and dequeue vm0 to vm4, and minus the count by 5.
>>>>>> 4.Sleep some time, and go to step 2.
>>>>>> _______________________________________________
>>>>>> Users mailing list
>>>>>> Users at ovirt.org
>>>>>> http://lists.ovirt.org/mailman/listinfo/users
>>>>>
>>>>> hooks run one on vm-start one by one. would be a bit tricky to do the
>>>>> above.
>>>>> roy - didn't you add some mechanism to throttle boot storms in the
>>>>> engine?
>>>> yes at RunVmCommandBase.delay(Guid vdsId) - but it doesn't fit here.
>>>> It'll delay the VM run only when there is no free memory to run the VM
>>>> and will wait till engine signals after gathering statistics of
>>>> powering up VMs.
>>>
>>> lofyer - any other issue other than memory bottleneck you were trying
>>> to resolve?
>>>
>>> Thanks,
>>> Itamar
>> I think only cpu_load here. If I start 8 VMs(1G memory each) in a 16G
>> host, it will be very slow for VMs to enter the desktop mode from the
>> time I click "start".
>> At first I thought it would be a resolution if I put these boot
>> processes into a linear squence or delay a random period by using hooks.
>> Is there an option that I can choose to arrange the boot squence in
>> the engine?
>> However, since each VM takes quite a long time to startup, there is no
>> need to do that. Just plug in more CPUs......
> Knowing that some other factors will affect it, can I use an SSD as a
> "boot cache"?

not sure, worth trying out i guess