Re: [Boost-users] [spirit] benchmarks/qi benchmarks valid?

Subject: Re: [Boost-users] [spirit] benchmarks/qi benchmarks valid?
From: Joel de Guzman (joel_at_[hidden])
Date: 2009-09-14 12:43:40

Christopher Jefferson wrote:
> 
> On 14 Sep 2009, at 16:21, Joel de Guzman wrote:
> 
>> Steven Watanabe wrote:
>>> AMDG
>>> Daniel Mierswa wrote:
>>>> I was merely wondering if what I'm doing is right or if I fail at 
>>>> basic benchmarking:
>>>>
>>>> impulze_at_istari 
>>>> ~/dev/repositories/boost.svn/libs/spirit/benchmarks/qi $ g++ -O3 
>>>> int_parser.cpp -I../../../../ -lrt && ./a.out
>>>> <snip>
>>>> atoi_test:            5.0041852930 [s] {checksum: 13f6bf40}
>>>> strtol_test:          5.4193627260 [s] {checksum: 13f6bf40}
>>>> spirit_int_test:      2.2137115780 [s] {checksum: 13f6bf40}
>>>>
>>>>
>>>> impulze_at_istari 
>>>> ~/dev/repositories/boost.svn/libs/spirit/benchmarks/qi $ g++ -O0 
>>>> int_parser.cpp -I../../../../ -lrt && ./a.out
>>>> <snip>
>>>> atoi_test:            0.5902040060 [s] {checksum: e9ed193a}
>>>> strtol_test:          0.6001010490 [s] {checksum: e9ed193a}
>>>> spirit_int_test:      3.6562933090 [s] {checksum: e9ed193a}
>>> -O0 means no optimization.
>>>> According to this, the optimized binary is 10 times slower wrt to 
>>>> the atoi/strtol implementation. I find that somehow quite hard to 
>>>> believe, is my toolchain broken, the testsuite or is it really true? 
>>>> The level of optimization doesn't matter btw, I get similar results 
>>>> with -O[,1,2]
>>
>> This has been discussed in the Spirit list. Seems that the test
>> is skewed bigtime with no optimization. The benchmarks were
>> designed with full optimization, of course.
> 
> I think the problem is why do atoi and strtol get 10x faster with no 
> optimisation?

Not in my machine. I can't reproduce his results. So,
I don't know.

Regards,
-- 
Joel de Guzman
http://www.boostpro.com
http://spirit.sf.net