On 07/06/2012 01:26, Florian Smeets wrote: > On 05.06.12 16:29, Mark Felder wrote: >> On Sat, 02 Jun 2012 06:49:18 -0500, Florian Smeets <f...@freebsd.org> wrote: >> >>> As far as i understand it does at least enable usage of pages up to 4MB, >>> perhaps someone should teach mysql about the FreeBSD's limits? >>> If you look at the output i sent, it certainly changes from using no >>> superpage mappings at all to using them to some degree, if you script >>> can be trusted >> >> Wow, this is a nice find. If someone were to add a patch for FreeBSD's >> superpages we might be able to get a nice little performance boost with >> little effort. Even the increase to 4MB for now is a welcome improvement. >> I'll make sure to put this in my toolbox.... > > I played with this some more. MySQL does not seem to use superpages. > After a mysqld restart Ivan's script and procstat showed superpage > mappings for mysqld, but it seems once MySQL "touches" the memory it's > not in superpages anymore. I looked at the MySQL code a bit and one > would need to add FreeBSD support in a couple of places. Perhaps I'll > find some time to try this, but i cannot make any promises.
If I understand how superpages are promoted correctly, you may get a nice effect simply by changing malloc()s of 2MB+ sizes to calloc()s.
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