[Haskell-cafe] How to benckmark a Word64 -> Bool?

[Gregory Collins]

This version is about 2x as fast as OP's on my system (look at h2.hs):
https://gist.github.com/gregorycollins/9103248

$  time ./dist/build/h1/h1 50000000 +RTS -A4M > /dev/null
./dist/build/h1/h1 50000000 +RTS -A4M > /dev/null  23.88s user 0.06s system
99% cpu 24.003 total

$  time ./dist/build/h2/h2 50000000 +RTS -A4M > /dev/null
./dist/build/h2/h2 50000000 +RTS -A4M > /dev/null  13.57s user 0.09s system
99% cpu 13.706 total

$  time ./dist/build/h3/h3 50000000 +RTS -A4M > /dev/null
./dist/build/h3/h3 50000000 +RTS -A4M > /dev/null  24.24s user 0.18s system
99% cpu 24.490 total

The "system" number here is especially telling: this program is spending
almost all of its time in syscalls.

G


On Wed, Feb 19, 2014 at 12:47 PM, Charles-Pierre Astolfi <cpa at crans.org>wrote:

> Thanks Erik!
>
> I was kind of hoping for such a benchmark. On my system, the C version is
> consistently twice as fast as the Haskell version. (I tried -fllvm, but it
> doesn't change perf)
>
> Then I added bang patterns for the argument of only012 and in the tuple
> (p,q) and it now has the same runtime as C.
>
> Just for fun, I tried to void writing explicit recursion and used only
> combinators and this Haskell code is still as competitive as C, so the real
> bottleneck really was the laziness in the tuple/argument.
>
> http://lpaste.net/100153
>
> In fact, this Haskell version takes 8 sec vs 10 sec for the C version on
> my laptop (input: 1000000000).
>
> I tried using Data.List.Stream, I couldn't get any performance gain,
> probably because the code is very close to optimal.
>
> So remember kids:
> - Bang pattern the heck out of your code (not a silver bullet, but
> definitely worth trying).
> - Don't rely on too much IO for benchmark.
> - Don't be afraid of combinators even if you want performance.
> - Ask on haskell-cafe, chaps here are very helpful :)
>
>
> --
> Cp
>
>
> On Wed, Feb 19, 2014 at 8:39 PM, Erik Rantapaa <erantapaa at gmail.com>wrote:
>
>> I think a lot is being obscured by the IO subsystem.
>>
>> If you print just a count of the only012 numbers I get very different
>> results.
>>
>> Here are the versions I compared:
>>
>> http://lpaste.net/100142
>>
>> and on my system the C version is about 10x faster.
>>
>>
>> On Wednesday, February 19, 2014 12:49:36 PM UTC-6, Charles-Pierre Astolfi
>> wrote:
>>
>>> Switching to quotRem gave no measurable improvements.
>>> After switching to ByteString, the code now runs in 9 seconds, which
>>> outperforms my C version. But honestly, I have no idea why.
>>>
>>> New code:
>>> http://lpaste.net/100136
>>>
>>> $ ghc --make -O3 303only012.hs && time ./303only012 50000000 > /dev/null
>>> ./303only012 50000000 > /dev/null  9.72s user 0.21s system 90% cpu
>>> 10.961 total
>>>
>>> @Alois, I'm not sure how criterion can help compare my code with the C
>>> version, since in the C version I cannot measure the exec time of only012
>>> only. What did you have in mind?
>>>
>>> Thanks everyone!
>>>
>>>
>>> --
>>> Cp
>>>
>>>
>>> On Wed, Feb 19, 2014 at 7:24 PM, Levent Erkok <erk... at gmail.com> wrote:
>>>
>>>>  Also, prefer quotRem over divMod as the former is faster. See here:
>>>> http://stackoverflow.com/questions/339719/when-is-
>>>> the-difference-between-quotrem-and-divmod-useful
>>>>
>>>>
>>>> On Wed, Feb 19, 2014 at 10:19 AM, Gregory Collins <
>>>> gr... at gregorycollins.net> wrote:
>>>>
>>>>>
>>>>> On Wed, Feb 19, 2014 at 9:36 AM, Charles-Pierre Astolfi <
>>>>> c... at crans.org> wrote:
>>>>>
>>>>>> So there's a difference, but I'm not sure if it's related to my
>>>>>> algorithm or related to IO/RTS.
>>>>>
>>>>>
>>>>> Text.Printf is slower than the C version (and uses String). Use
>>>>> Data.ByteString.putStr instead.
>>>>>
>>>>>
>>>>>
>>>>> --
>>>>> Gregory Collins <gr... at gregorycollins.net>
>>>>>
>>>>> _______________________________________________
>>>>> Haskell-Cafe mailing list
>>>>> Haskel... at haskell.org
>>>>> http://www.haskell.org/mailman/listinfo/haskell-cafe
>>>>>
>>>>>
>>>>
>>>
>
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>


-- 
Gregory Collins <greg at gregorycollins.net>
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