On 9 January 2017 at 10:01, Jin Guojie <[email protected]> wrote: > * in configure, the default optimization level is changed to O3. > * Tested successfully on following machines: > > | Host machine | Host OS | qemu-system | Debian ISO | > |-----------------------------------------------------| > | x86 64 | Fedora25 | i386 | i386 | > | mips 64 le | Fedora25 | i386 | i386 | > > Signed-off-by: Jin Guojie <[email protected]> > > Jin Guojie (1): > Change default CFLAGS to -O3 > > configure | 4 ++-- > 1 file changed, 2 insertions(+), 2 deletions(-)
...so what are the measured performance improvements from this change? As I understand it -O3 is where the "trade off code size for speed" optimisations kick in, so we need to benchmark to be sure that the increased icache usage doesn't outweigh any speed gains. -O3 is not guaranteed to be strictly better than -O2 (which is why for instance Debian and Gentoo recommend -O2 as their default). thanks -- PMM
