До чего ж у людей
интересная работа (писать MySQL
Cluster). Правда трудная маманегорюй, но
интересная же!
Такой хайлоад, что
значимым становится даже время обновления
процессорного кеша
Next we noted using oprofile that
there was a few functions that for some reason 50% of the CPU time
was spent. This was quite surprising and given that the exactness of
those measurements is not always 100%, I was very suspicious about
those numbers. Eventually however the reason dawned on me.
The reason was that I had some cache
lines that was too often updated. This lead to that some instructions
took several microseconds to execute since all threads were
serialised on updating this cacheline.
... bitmap is obviously global and
this was updated every time we made a remote send to another node.
This was obviously quite unnecessary to update it every time, it's
enough to update when the state changes, so a simple if-statement
resolved that problem.
…
With all these changes implemented
we managed to scale update and read performance linearly up to 30
nodes.
Подозрительно, да.
Профайлер показывает, что проц загружен
не на 100%! Прохлаждается, сцука. Работать,
я сказал! Правда ведь, интересно и
прикольно — какая кухня в таком проекте?
Исторический экскурс
The MySQL Cluster architecture is
based on a design that is used in the world's most sold telecom
switch, the AXE switch. This switch is used in all mobile networks
delivered by Ericsson. MySQL Cluster also originates from Ericsson.
... The architecture was inspired by how HW was designed. In HW
design each module can only communicate with other HW modules using
signals (mostly electrical). The idea of the AXE architecture was to
use this architecture also for software. The basic concept of this
architecture is blocks and signals.
Странно, что про Erlang не
упомянул. В конце поста автор проводит
интересную параллель — в 1990-х частота
х86 процессоров выросла с 25 мегагерц до
1 гигагерца; нынче же, в 2010-х автор уже
сделал СУБД выполняющую запросы с
частотой 17.6 мегагерц и готов покорять
следующие вершины. Так вот, к концу
2010-х кто сделает СУБД побивающую планку
в 1 гигагерц?
Если кто еще не в курсе,
лучшая книга администратора Debian таки
вышла на свободу
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