[nova][scheduler] - Stack VMs based on RAM

Georgios Dimitrakakis giorgis at acmac.uoc.gr
Wed Apr 17 22:13:42 UTC 2019


Shouldn’t that be the correct behavior and place the new VM on the host with the smaller weight? Isn’t that what the negative value for “ram_weight_multiplier” does ?

Please let me know how I can provide to you more debug info....

Best,

G.

>> On 4/17/2019 3:50 PM, Georgios Dimitrakakis wrote:
>> And here is the new log where spawning of 2 VMs can be seen with a few seconds of difference: https://pastebin.com/Xy2FL2KL
>> Initially both hosts are of weight 1.0 then the one with one VM already running has negative weight but the new VM is placed on the other host.
>> Really-really strange why this is happening...
> 
> < 2019-04-17 23:26:18.770 157355 DEBUG nova.scheduler.filter_scheduler [req-14c666e4-3ff4-4d88-947e-377b3d37bff9 6a4c2e32919e4a6fa5c5d956beb68eef 9f22e9bfa7974e14871d58bbb62242b2 - default default] Filtered [(cpu2, cpu2) ram: 30105MB disk: 1887232MB io_ops: 1 instances: 1, (cpu1, cpu1) ram: 32153MB disk: 1906688MB io_ops: 0 instances: 0] _get_sorted_hosts /usr/lib/python2.7/site-packages/nova/scheduler/filter_scheduler.py:435
> 
> < 2019-04-17 23:26:18.771 157355 DEBUG nova.scheduler.filter_scheduler [req-14c666e4-3ff4-4d88-947e-377b3d37bff9 6a4c2e32919e4a6fa5c5d956beb68eef 9f22e9bfa7974e14871d58bbb62242b2 - default default] Weighed [WeighedHost [host: (cpu1, cpu1) ram: 32153MB disk: 1906688MB io_ops: 0 instances: 0, weight: 1.0], WeighedHost [host: (cpu2, cpu2) ram: 30105MB disk: 1887232MB io_ops: 1 instances: 1, weight: -0.00900862553213]] _get_sorted_hosts /usr/lib/python2.7/site-packages/nova/scheduler/filter_scheduler.py:454
> 
> cpu1 is definitely getting weighed higher but I'm not sure why. We likely need some debug logging on the result of each weigher like we have for each filter to figure out what's going on with the weighers.
> 
> -- 
> 
> Thanks,
> 
> Matt




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