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Remove obsolete MaxAdmin documentation

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The rest needs an overhaul, but the removed text is completely
obsolete.
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Johan Wikman
2018-11-05 10:52:00 +02:00
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Documentation/Reference/MaxAdmin.md
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@ -1743,49 +1743,6 @@ path is `/home/user/rules.txt`.
# Tuning MariaDB MaxScale
The way that MariaDB MaxScale does its polling is that each of the polling
threads, as defined by the threads parameter in the configuration file, will
call epoll_wait to obtain the events that are to be processed. The events are
then added to a queue for execution. Any thread can read from this queue, not
just the thread that added the event.
Once the thread has done an epoll call with no timeout it will either do an
epoll_wait call with a timeout or it will take an event from the queue if there
is one. These two new parameters affect this behavior.
The first parameter, which may be set by using the non_blocking_polls option in
the configuration file, controls the number of epoll_wait calls that will be
issued without a timeout before MariaDB MaxScale will make a call with a timeout
value. The advantage of performing a call without a timeout is that the kernel
treats this case as different and will not rescheduled the process in this
case. If a timeout is passed then the system call will cause the MariaDB
MaxScale thread to be put back in the scheduling queue and may result in lost
CPU time to MariaDB MaxScale. Setting the value of this parameter too high will
cause MariaDB MaxScale to consume a lot of CPU when there is infrequent work to
be done. The default value of this parameter is 3.
This parameter may also be set via the maxadmin client using the command _set
nbpolls <number>_.
The second parameter is the maximum sleep value that MariaDB MaxScale will pass
to epoll_wait. What normally happens is that MariaDB MaxScale will do an
epoll_wait call with a sleep value that is 10% of the maximum, each time the
returns and there is no more work to be done MariaDB MaxScale will increase this
percentage by 10%. This will continue until the maximum value is reached or
until there is some work to be done. Once the thread finds some work to be done
it will reset the sleep time it uses to 10% of the maximum.
The maximum sleep time is set in milliseconds and can be placed in the
[maxscale] section of the configuration file with the poll_sleep
parameter. Alternatively it may be set in the maxadmin client using the command
_set pollsleep <number>_. The default value of this parameter is 1000.
Setting this value too high means that if a thread collects a large number of
events and adds to the event queue, the other threads might not return from the
epoll_wait calls they are running for some time resulting in less overall
performance. Setting the sleep time too low will cause MariaDB MaxScale to wake
up too often and consume CPU time when there is no work to be done.
The _show epoll_ command can be used to see how often we actually poll with a
timeout, the first two values output are significant. Also the "Number of wake
with pending events" is a good measure. This is the count of the number of times