Re: [microblaze-uclinux] another compiler oddity

[Yasushi SHOJI <yashi@xxxxxxxxxxxxxxxxx>]

Hi John,

At Tue, 24 Aug 2004 08:34:13 +1000,
John Williams wrote:
[...]
> A cosmetically modified version of your test program (see attached) 
> gives me this result:
> 
> # /mnt/yashitest
> 
> DRAM test 
> do_test_inline(): 
> Elapsed time : 0.55982 
> do_test(): 
> Elapsed time : 0.46411 
> 
> 
> BRAM test 
> do_test_inline(): 
> Elapsed time : 0.23753 
> do_test() 
> Elapsed time : 0.23693


ok here is the result form _unmodified_ version of your code:

# /var/hello
DRAM test
do_test_inline():
Elapsed time : 0.31983
do_test():
Elapsed time : 0.32392


BRAM test
do_test_inline():
Elapsed time : 0.18018
do_test()
Elapsed time : 0.17902

> So, a couple of observations.
> 
> 1 - your times are quicker overall than on my mbvanilla platform (66MHz 
> clock, icache and cache enabled

odd... this test is done on a SUZAKU running 51MHz, icache enabled and
dcache _disabled_.

LOPT, UOPT is not defined in config.arch so it uses the default
vendors/Xilinx/common/common-config.arch, which is -Os for user app.

> 2 - I see the inverse effect to you (ie BRAM quicker than DRAM) as expected.

your code doesn't show the oddity on SUZAKU.... hmmm...  

> So, what does it all mean?!  Is your platform's timekeeping accurate? 
> If you open the loop right out (or make it a double loop) and compare 
> the reported elapsed time with wallclock time, does it add up?

I'll recheck and post the result.  thank you for your help, John.

best,
--
            yashi
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