On Fri, Oct 21, 2011 at 7:48 AM, James Tunnicliffe james.tunnicliffe@linaro.org wrote:
This isn't exactly overflowing with up to date numbers, but...
http://elinux.org/images/8/8a/Experiment_with_Linux_and_ARM_Thumb-2_ISA.pdf
Slides 14 and 15 say that across EEMBC Thumb-2 gives 98% of the performance of ARM 32 bit instructions (assume performance optimised) and binaries are 26% smaller (didn't catch what binary/binaries that was). These are numbers from 2007 and benchmarked on an ARM 11. I assume using ARMCC.
I just ran EEMBC with gcc-linaro-4.6-2011.10 with -mfpu=neon -O3 -mtune=cortex-a9 and got similar numbers. Five of the 32 tests ran faster with Thumb-2 which is nice. I'll send the results privately as I'm not sure we can share.
EEMBC embeds the test data in the executable so it it's hard to tell the change in text size. After de-duplicating, the average on-disk package size was 88 % of the ARM version. Ignoring the ones that are likely to have embedded test data, the average text size was 82 % of ARM mode.
These days we're not really short of RAM so, as Mans says, improvements in startup time, cache footprint, or on-disk size might be a win.
-- Michael