Sean,
I will try tweaking those settings you suggest.
In terms of the CPU usage we see 60% on average across the whole 12
CPU's so approx 720-790% in total with no one cpu maxed out.
Dave
On 9 Dec 2010, at 14:04, Sean Cribbs wrote:
> If you're using ETS, then yes that makes sense that the majority of the time
> would be CPU (there's no disk to wait on!). One thing - when you say 60% of
> available CPU, is that 60% of one core, or 60% of 12 cores (sometimes
> reported as 720%)? The latter seems highly unlikely.
>
> There are some generic things you can do to tweak Erlang and Riak for
> multicore computers, many of them referenced on this page:
> http://erlang.org/doc/man/erl.html Of special note are:
>
> +A - how many OS threads will be in the async thread pool (handles IO, some
> system calls)
> +S - the number of scheduler threads to create (usually 1 thread per CPU)
> +sct - specify the CPU topology (useful for NUMA processors like Nehalem)
>
> Sean Cribbs <[email protected]>
> Developer Advocate
> Basho Technologies, Inc.
> http://basho.com/
>
> On Dec 9, 2010, at 5:40 AM, David Dawson wrote:
>
>> Sean,
>>
>> We have used the ETS backend, to rule out Disk IO as much as possible
>> and we are pretty sure that our memory IO is fine, this leaves either
>> Network IO being a factor or the erlang VM itself ( highly unlikely ). In
>> further testing we also discovered that just using 1 node in the ring gave
>> us 80% cpu / 0% wait / 17% idle / 3% sys, which could suggest that network
>> chatter between the ring could be the factor, so we are planning to setup
>> the RIAK ring so the handoff and chatter traffic is done over a separate
>> NIC, in your experiences will this help?
>>
>> Dave
>>
>>
>> On 8 Dec 2010, at 17:57, Sean Cribbs wrote:
>>
>>> David,
>>>
>>> It's expected that, especially when running basho_bench, your cluster will
>>> not use that much CPU. Riak is mostly I/O-bound, which is a good thing (vs.
>>> wasting CPU not delivering data to you). I would definitely expect network
>>> and disk (and possibly RAM) to be the primary limiting factors.
>>>
>>> Sean Cribbs <[email protected]>
>>> Developer Advocate
>>> Basho Technologies, Inc.
>>> http://basho.com/
>>>
>>> On Dec 8, 2010, at 12:36 PM, David Dawson wrote:
>>>
>>>> We are currently running a ring of 3 machines each machine with 12 cores,
>>>> and have noticed that we seem to only be using 60% of available CPU (
>>>> other 40% is spent idle ) when running basho bench against the cluster. We
>>>> have tried changing the 'n_val' from 3 to 1 and also the backend from
>>>> bitcask to ets, and it seems to make no difference. Is this expected?
>>>>
>>>> Also are there any suggested tuning parameters that should be used when
>>>> running riak on machines with lots of cores? and if not what would you
>>>> expect the bottleneck to be in a cluster? ( cpu / disk io/ memory /
>>>> network io )
>>>>
>>>> Dave
>>>>
>>>>
>>>>
>>>> _______________________________________________
>>>> riak-users mailing list
>>>> [email protected]
>>>> http://lists.basho.com/mailman/listinfo/riak-users_lists.basho.com
>>>
>>
>
_______________________________________________
riak-users mailing list
[email protected]
http://lists.basho.com/mailman/listinfo/riak-users_lists.basho.com
