Re: GiST index performance

On Thu, 11 Jun 2009, Tom Lane wrote:
> So it'd be worth converting your functions to V1 style.

Does that produce a significant reduction in overhead? (You'll probably
say "yes, that's the whole point").

> hmm ... memcpy or qsort maybe?

Surprise:

CPU: Core 2, speed 1998 MHz (estimated)
Counted CPU_CLK_UNHALTED events (Clock cycles when not halted) with a unit mask of 0x00 (Unhalted core cycles) count 100000
samples % image name app name symbol name
3005354 40.2868 libc-2.9.so libc-2.9.so __mcount_internal
1195592 16.0269 libc-2.9.so libc-2.9.so mcount
549998 7.3727 postgres postgres gistnext
420465 5.6363 postgres postgres fmgr_oldstyle
376333 5.0447 no-vmlinux no-vmlinux (no symbols)
210984 2.8282 postgres postgres FunctionCall5
182509 2.4465 postgres postgres gistdentryinit
174356 2.3372 btree_gist.so btree_gist.so gbt_int4_consistent
142829 1.9146 postgres postgres FunctionCall1
129800 1.7400 postgres postgres .plt
119180 1.5976 nvidia_drv.so nvidia_drv.so (no symbols)
96351 1.2916 libxul.so libxul.so (no symbols)
91726 1.2296 btree_gist.so btree_gist.so gbt_num_consistent

A quick grep in the postgres source for mcount reveals no hits. No idea
what it does - there is no man page for it.

Matthew

--
I pause for breath to allow you to get over your shock that I really did cover
all that in only five minutes... -- Computer Science Lecturer