[SR-Users] suggested number of TCP / UDP workers for version 3.1.x

[Francesco Castellano]

Daniel,

thank you very much.

May I ask you another question? We used to re-compile the production
proxy with a high value (32 MB) of PKG_SIZE, for older versions of the
MySQL db module didn't provide fetch_result() capability. But now,
apart from start up loading issues, are there any other reason to keep
the PKG_SIZE above the 4MB default?

Thank you,

Best regards,
Francesco

On Fri, Aug 5, 2011 at 6:02 PM, Daniel-Constantin Mierla
<miconda at gmail.com> wrote:
> Hello,
>
> On 8/3/11 6:28 PM, Francesco Castellano wrote:
>>
>> Dear sirs,
>>
>> searching on the web and in old ML threads about the suggested number
>> of TCP and UDP workers, I just found:
>>
>> - for TCP children (i.e., TCP receivers, isn't it?)
>> "As a rule of thumb, (maximum simultaneous connections)/2000 should be
>> OK" (from doc/tcp_tunning.txt)
>>
>> - In general for workers (from a past thread by Henning Westerholt):
>> "In my experience the number of children is not that important for
>> performance, you may just choose the default size of 8."
>>
>> In the last post there was, moreover, a suggestion that the number of
>> children should be chosen with respect to RAM and CPU cores (that
>> makes sense to me).
>>
>> The only thing I can think about the rule of thumb above comes from
>> the possibility that a number of processes may be unavailable in
>> blocking operations. So my question is:
>>
>> - with asynchronous TCP/TLS is it safe to assume that more children
>> than CPU cores are more or less useless?
>
> No, unless you have a lot of cores. There is a lot of I/O with the
> networking, database a.s.o. The number of children is a matter of traffic
> and the time consuming operations you do (db lookups, dns).
>
>> - are there other blocking operations for which the number of UDP/TCP
>> children should be incremented above the CPU cores number?
>
> No matter the number of cores, in production I start from 8 children and
> don't go more than 32. After this value, either the config is too blocking
> or the traffic is too high and it is time for new hardware. I am talking
> about usual server hardware, not supercomputers.
>
> Cheers,
> Daniel
>
> --
> Daniel-Constantin Mierla -- http://www.asipto.com
> Kamailio Advanced Training, Oct 10-13, Berlin: http://asipto.com/u/kat
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>
>