On Wed, Oct 20, 2010 at 12:28:25PM -0700, Greg Stark wrote: > On Wed, Oct 20, 2010 at 12:17 PM, Greg Stark <gsst...@mit.edu> wrote: > > I don't think it's a big cost once all the processes > > have been forked if you're reusing them beyond perhaps slightly more > > efficient cache usage. > > Hm, this site claims to get a 13% win just from the reduced tlb misses > using a preload hack with Pg 8.2. That would be pretty substantial. > > http://oss.linbit.com/hugetlb/
That was my motivation in trying a patch. TLB misses can be a substantial overhead. I'm not current on the state of play, but working at Sun's benchmark lab on a DB TPC-B benchmark something for the first generation of MP systems, something like 30% of all bus traffic was TLB misses. The next iteration of the hardward had a much larger TLB. I have a client with 512GB memory systems, currently with 128GB configured as postgresql buffer cache. Which is 32M TLB entires trying to fit in the few dozed cpu TLB slots. I suspect there may be some contention. I'll benchmark of course. -dg -- David Gould da...@sonic.net 510 536 1443 510 282 0869 If simplicity worked, the world would be overrun with insects. -- Sent via pgsql-hackers mailing list (pgsql-hackers@postgresql.org) To make changes to your subscription: http://www.postgresql.org/mailpref/pgsql-hackers
