Hi,
From: Rik van Riel <riel@xxxxxxxxxx>Hiro Yoshioka wrote:snipHowdy,
MySQL 5.0.26 had some scalability issues and it solved since 5.0.32
http://ossipedia.ipa.go.jp/capacity/EV0612260303/
(written in Japanese but you may read the graph. We compared
5.0.24 vs 5.0.32)
MySQL tries to get a mutex but it spends about 16.8% of CPU on 8 coreThat's one aspect.
machine.
I think there are a lot of room to be inproved in MySQL implementation.
The other aspect of the problem is that when the number of
threads exceeds the number of CPU cores, Linux no longer
manages to keep the CPUs busy and we get a lot of idle time.
On the other hand, with the number of threads being equal to
the number of CPU cores, we are 100% CPU bound...
I have a question. If so, what is the difference of kernel's
view between SMP and CPU cores?
Another question. When the number of threads exceeds the number of
CPU cores, we may get a lot of idle time. Then a workaround of
MySQL is that do not creat threads which exceeds the number
of CPU cores. Is it right?