I was mistaken, I am using libc l.6.1
I re-ran tests using simulavr and gdb and got exactly same results as
AVRORA. So the timing is right.
4.3 take different decision regarding inlining and loop unrolling - some
good, some bad.
But these are controllable with compiler switches.
4.3 can be really smart, quite a lot of the testsuite cases get
optimised into a simple exit(1) at O3
So benchmarks can be very problematic.
Unfortunately due to this I cant see if my changes have any good or bad
effect until I create head version again
for direct comparison.
In 4.3 libc definition in maths.h are being included. (added about 30
bytes) - think they got linked too!
Tried Winavr compiler with same setting and not sure what library
version I have for 4.2
There is no way to tell after its built but I guess it might be 1.2
So instead look at xlib as size without library function
text xlib cycles
Os 4540 2276 89824
O3 5690 3426 79875
4.3.0 (my version)
Os 4646 2378 87500
O3 6068 3800 75633 -fno-unit-at-a-time
All with:
-funsigned-char -fno-unit-at-a-time -funsigned-bitfields -fpack-struct
-fshort-enums \
-Wall -Wstrict-prototypes -I$(DIRINC) \
All pretty meaningless really!
Andy H wrote:
Here is figures I get from gcc head of yesterday and my development
build.
The results are sensitive to build options so I
do not know if difference are valid. I used AVRORA - which apparently
has good timing model.
(I would have used Simulavr - but I have never used it to do this sort
of thing.)
Sorry libc seems to be at 1.2.0 - I have not got around to updating
it. BUT how I can I check a build for library version info?????
.text cycles
Os 4646 87500
O3 6068 75633 -fno-unit-at-a-time
O3 5998 31752
Why "unit at a time" compilation produced faster result ? But the
code was totally inlined and perhaps it optimised out something that
it should not have for this purpose.
Weddington, Eric wrote:
-----Original Message-----
From: [EMAIL PROTECTED]
[mailto:[EMAIL PROTECTED]
org] On Behalf Of Dmitry K.
Sent: Monday, January 21, 2008 3:08 PM
To: [email protected]
Subject: Re: [avr-gcc-list] Whetstone Benchmark
On Monday 21 January 2008 11:00, Weddington, Eric wrote:
A couple of quick comments/suggestions:
- Please drop -morder1. We generally don't recommend this
to users, and
it looks like it really doesn't affect the results that much
- Can you also try with avr-gc 4.2.2 and avr-libc 1.6.1?
These are the
latest released versions.
Flash Cycles Avr-gcc Options
----- ------ ------- ----------------------
4296 88807 4.0.4 -Os
4484 80839 4.0.4 -O3
4030 88565 4.1.2 -Os
5332 71751 4.1.2 -O3
4194 89204 4.2.2 -Os
5388 72643 4.2.2 -O3
4350 86986 4.3.X -Os
5608 75351 4.3.X -O3 -fno-unit-at-a-time
Thanks again for doing this!
Can you tell me how you measured code size and number of cycles?
Thanks,
Eric Weddington
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