From: Robert Hancock <[EMAIL PROTECTED]> Subject: Re: SMP performance degradation with sysbench Date: Tue, 27 Feb 2007 18:20:25 -0600 Message-ID: <[EMAIL PROTECTED]>
> 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? Yes, it is. Regards, Hiro - To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to [EMAIL PROTECTED] More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
