5 Aug
2011
5 Aug
'11
7:02 p.m.
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
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