Messages in this thread | | | Date | Tue, 27 Feb 2007 18:20:25 -0600 | From | Robert Hancock <> | Subject | Re: SMP performance degradation with sysbench |
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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.
Curious that it calls pthread_mutex_trylock (as opposed to pthread_mutex_lock) so often. Maybe they're doing some kind of mutex lock busy-looping?
-- Robert Hancock Saskatoon, SK, Canada To email, remove "nospam" from hancockr@nospamshaw.ca Home Page: http://www.roberthancock.com/
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