Hi Davi, thanks for this information, it is really useful.
According to bzr history fast mutex was added back in 2005. I have a few guesses why it would have been needed: - probably at that time mutex implementation wasn't as good as it is now - probably mutex implementation on some specific platform isn't good enough As for the hardware: I ran my benchmark on Core 2 Duo (from 2006) but with recent Ubuntu installed. Results were very similar: fast mutex was outsider. Moreover adaptive mutex does very similar job much better. Still not as good as normal mutex. Thanks, Sergey On Thu, Feb 27, 2014 at 09:08:42PM -0800, Davi Arnaut wrote: > Hi Sergey, > > I looked into fast mutex in the past [1] and was never able to get a > straight answer (even from the original developer) on what was the > intention behind it and how it made things faster as it actually made > things slower in the past (Bug#38941, others). There is a comment in > http://bugs.mysql.com/bug.php?id=58766 highlighting one case where I saw a > small performance improvement, but even that was highly workload/hardware > dependent (can't recall which workload exactly, might have been sysbench's > point select or something similar). > > 1. http://dev.mysql.com/worklog/task/?id=4601 > > > > On Wed, Feb 26, 2014 at 10:36 PM, Sergey Vojtovich <[email protected]> wrote: > > > Hi Sergei, > > > > do you know if we ship any binaries with fast mutex > > (-DMY_PTHREAD_FASTMUTEX) > > enabled or officially suggest it? What was it's intention and what loads > > it was > > supposed to make faster? > > > > I'm trying to understand if fastmutex is worth fixing. It looks like > > duplication > > of PTHREAD_MUTEX_ADAPTIVE_NP, so we have double spinning when they're > > enabled. > > According to my recent benchmarks it shown worst performance. > > > > Thanks, > > Sergey > > > > _______________________________________________ > > Mailing list: https://launchpad.net/~maria-developers > > Post to : [email protected] > > Unsubscribe : https://launchpad.net/~maria-developers > > More help : https://help.launchpad.net/ListHelp > > _______________________________________________ Mailing list: https://launchpad.net/~maria-developers Post to : [email protected] Unsubscribe : https://launchpad.net/~maria-developers More help : https://help.launchpad.net/ListHelp
