Hi Nav, On Tue, Nov 24, 2009 at 08:53:11PM +0000, Nava Whiteford wrote: > >> http://linuxjunk.blogspot.com/2009/11/are-templates-faster-than-subclasses.html > > > I didn't see the first version. In the current version, the templated > > code is simple enough that the optimizer can figure out the whole thing > > and skip everything. The virtual code is not simple enough, so the code > > actually executes. > > Ah ok, so it's able to optimise my loop in to a single multiply here? That's neat. > > > So you still aren't measuring what you set out to measure. > > I've constructed a slightly more complicated test: > > http://linuxjunk.blogspot.com/2009/11/templates-v-subclasses-v2.html > > In this case the templated version doesn't seem to have the same huge > advantage. Templated 20.73s against 21.1s for the classed version. I would guess > real, but not huge. May be another test would be to use a very simple function - and in addition forbid gcc to inline or optimize away the function calls: If you define the function as: int get_i() __attribute__((noinline)){ asm(""); return i*i; } it will be neither inlined nor the calls can't be optimized away (see http://gcc.gnu.org/onlinedocs/gcc/Function-Attributes.html). Then, you really can make the functions as small as possible (e.g. doing nothing) and compare the time needed to call them. Axel
