On Monday 29 November 2010 17:57:51 Robert Haas wrote: > On Sun, Nov 28, 2010 at 11:51 PM, Tom Lane <t...@sss.pgh.pa.us> wrote: > > Robert Haas <robertmh...@gmail.com> writes: > >> Yeah, very true. What's a bit frustrating about the whole thing is > >> that we spend a lot of time pulling data into the caches that's > >> basically static and never likely to change anywhere, ever. > > > > True. I wonder if we could do something like the relcache init file > > for the catcaches. > > Maybe. It's hard to know exactly what to pull in, though, nor is it > clear to me how much it would really save. You've got to keep the > thing up to date somehow, too. > > I finally got around to doing some testing of > page-faults-versus-actually-memory-initialization, using the attached > test program, compiled with warnings, but without optimization. > Typical results on MacOS X: > > first run: 297299 > second run: 99653 > > And on Fedora 12 (2.6.32.23-170.fc12.x86_64): > > first run: 509309 > second run: 114721 Hm. A quick test shows that its quite a bit faster if you allocate memory with: size_t s = 512*1024*1024; char *bss = mmap(0, s, PROT_READ|PROT_WRITE, MAP_PRIVATE|MAP_POPULATE| MAP_ANONYMOUS, -1, 0);
Andres -- Sent via pgsql-hackers mailing list (pgsql-hackers@postgresql.org) To make changes to your subscription: http://www.postgresql.org/mailpref/pgsql-hackers
