8 Aug
2011
8 Aug
'11
1:43 p.m.
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(a)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
--
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