[openstack-dev] [ceilometer] about workload partition

李田清 tianqing at unitedstack.com
Mon Dec 4 03:30:08 UTC 2017

On 2017-12-01 05:03 AM, 李田清 wrote:
>> Hello,
>>       we test workload partition, and find it's much slower than not 
>> using it.
>>       After some review, we find that, after get samples from 
>> notifications.sample
>>       ceilometer unpacks them and sends them one by one to the pipe
>>       ceilometer.pipe.*, this will make the consumer slow. Right now, 
>> the rabbit_qos_prefetch_count to 1. If we sent it to 10, the connection 
>> will be reset

> currently, i believe rabbit_qos_prefetch_count will be set to whatever 
> value you set batch_size to.
You mean in the past, it can not be set to whatever?
We test newton, and find under 1k vm, if we open workload partition,
it will be reset regularly. 

>>       regularly. Under this pos, the consumer will be very slow in 
>> workload partition. If you do not use workload partition, the messages 
>> can all be consumer. If you use it, the messages in pipe will be piled 
>> up more and more。

> what is "pos"? i'm not sure it means the same thing to both of us... or 
> well i guess it could :)
sorry, it is qos. this qos. 

>>      May be right now workload partition is not a good choice? Or any 
>> suggestion?

>i'll give a two part answer but first i'll start with a question: what 
>version of oslo.messaging do you have?

newton 5.10.2

>i see a performance drop as well but the reason for it is because of an 
>oslo.messaging bug introduced into master/pike/ocata releases. more 
>details can be found here: 
>https://bugs.launchpad.net/oslo.messaging/+bug/1734788. we're working >on 
>backporting it. we've also done some work regarding performance/memory 
>to shrink memory usage of partitioning in master[1].

>with that said, there are only two scenarios where you should have 
>partitioning enabled. if you have multiple notification agents AND:

>1. you have transformations in your pipeline
>2. you want to batch efficiently to gnocchi

>if you don't have workload partitioning on, your transform metrics will 
>probably be wrong or missing values. it also won't batch to gnocchi so 
>you'll see a lot more http requests there.

>so yes, you do have a choice to disable it, but the above is your tradeoff.



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