On Thu, 2014-09-04 at 14:37 -0400, Michael Goulish wrote:
> A little confirmation --
> in my testing of proton engine send/receive clients
> I just now tested the performance of those clients built against Proton
> Release version, versus Proton RelWithDebInfo version.
> I did indeed find that both versions were the same at running my tests,
> after averaging the speed of 5 tests with each version.
> In fact, RelWithDebInfo came in a mite faster -- a couple percent --
> but probably still within the variability of the observations.
CMakeCache.txt:126:CMAKE_CXX_FLAGS_RELWITHDEBINFO:STRING=-O2 -g -DNDEBUG
So the only differences are debug symbols (-g) and the extra
optimizations in -O3:
gcc -c -Q -O3 --help=optimizers > /tmp/O3-opts; gcc -c -Q -O2
--help=optimizers > /tmp/O2-opts; diff /tmp/O2-opts /tmp/O3-opts | grep
> -fgcse-after-reload [enabled]
> -finline-functions [enabled]
> -fipa-cp-clone [enabled]
> -fpredictive-commoning [enabled]
> -ftree-loop-distribute-patterns [enabled]
> -ftree-partial-pre [enabled]
> -ftree-vectorize [enabled]
> -funswitch-loops [enabled]
> -fvect-cost-model [enabled]
I'm not sure what any of those do except for -finline-functions which is