[rabbitmq-discuss] rabbitmq cpu usage can not be more than 700%

Jesper Louis Andersen jesper.louis.andersen at gmail.com
Wed Mar 13 10:57:50 GMT 2013


Highly plausible. The aggressiveness with which to start new cores changed
along the R15 path and R16 also has some very cool speedups w.r.t. message
passing. So it is nice to see that the efforts paid off.


On Wed, Mar 13, 2013 at 11:54 AM, Simon MacMullen <simon at rabbitmq.com>wrote:

> Just to follow up - Xie told me that an upgrade to R16B got them to 2300%
> utilisation.
>
> Cheers, Simon
>
>
> On 12/03/13 17:36, Jesper Louis Andersen wrote:
>
>> It is due to the way Erlang spins up more cores. The Erlang VM decides
>> at certain intervals how many cores it needs to satisfy the work it has.
>> If it never needs more than 7 cores to satisfy work, it will never spin
>> up more. Also note that it will keep a core "awake" even if there is no
>> work to do in the hope that work will arrive soon. So you cannot use a
>> command like top(1) to get any idea of what is happening.
>>
>> The way is to get a shell on an erlang node and then use
>>
>> http://erlang.org/doc/man/**erlang.html#statistics-1<http://erlang.org/doc/man/erlang.html#statistics-1>
>>
>> in particular the scheduler_wall_time stats to get a grip on scheduler
>> utilization.
>>
>> My guess would be that you are bound by something else than CPU.
>>
>>
>> On Thu, Mar 7, 2013 at 9:14 AM, Xie Yunpeng <woqimingweipeng at gmail.com
>> <mailto:woqimingweipeng at gmail.**com <woqimingweipeng at gmail.com>>> wrote:
>>
>>     rabbitmq version: 3.0.2
>>     cpu: 24 cores
>>     memory: 64G
>>     i deploy a rabbitmq service on the server above and do a stress
>>     testing , use 150 threads for send and 300 threads for recv on 150
>>     queues on the service, per queue with 1 send/ 2 recv.
>>     the cpu useage is always below 700%, no matter i increase queues and
>>     threads or not.
>>
>>     how to use more than 7 cores in rabbitmq?
>>
>>     i find smp is set to 24:24
>>     [rabbitmq]$ erl
>>     Erlang R15B03 (erts-5.9.3.1) [source] [64-bit] [smp:24:24]
>>     [async-threads:0] [hipe] [kernel-poll:false]
>>
>>     Eshell V5.9.3.1  (abort with ^G)
>>
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>>
>>
>> --
>> J.
>>
>>
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>>
>
> --
> Simon MacMullen
> RabbitMQ, VMware
>



-- 
J.
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