Hiro Yoshioka wrote:
Howdy,
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)
The following is oprofile data
==>
cpu=8-mysql=5.0.32-gcc=3.4/oprofile-eu=2200-op=default-none/opreport-l.txt
<==
CPU: Core Solo / Duo, speed 2666.76 MHz (estimated)
Counted CPU_CLK_UNHALTED events (Unhalted clock cycles) with a unit
mask of 0x00 (Unhalted core cycles) count 100000
samples % app name symbol name
47097502 16.8391 libpthread-2.3.4.so pthread_mutex_trylock
19636300 7.0207 libpthread-2.3.4.so pthread_mutex_unlock
18600010 6.6502 mysqld rec_get_offsets_func
18121328 6.4790 mysqld btr_search_guess_on_hash
11453095 4.0949 mysqld row_search_for_mysql
MySQL tries to get a mutex but it spends about 16.8% of CPU on 8 core
machine.
I think there are a lot of room to be inproved in MySQL implementation.
That's one aspect.
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...
--
Politics is the struggle between those who want to make their country
the best in the world, and those who believe it already is. Each group
calls the other unpatriotic.
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