Traversing an array of value types seen as an array of Object is slow

[forax at univ-mlv.fr]

----- Mail original -----
> De: "Roland Westrelin" <rwestrel at redhat.com>
> À: "Remi Forax" <forax at univ-mlv.fr>, "valhalla-dev" <valhalla-dev at openjdk.java.net>
> Envoyé: Vendredi 5 Octobre 2018 15:45:52
> Objet: Re: Traversing an array of value types seen as an array of Object is slow

> Hi Remi,
> 
>> I maybe wrong with the conclusion but this benchmark [1] show that there is
>> something fishy.
>>
>> Benchmark                                         Mode  Cnt    Score    Error
>> Units
>> ReifiedListBenchMark.arraylist_integer_get        avgt    9    0.068 ±  0.001
>> ms/op
>> ReifiedListBenchMark.arraylist_integer_iterator   avgt    9    0.069 ±  0.001
>> ms/op
>> ReifiedListBenchMark.reifiedlist_intbox_cursor    avgt    9  516.526 ± 11.903
>> ms/op
>> ReifiedListBenchMark.reifiedlist_intbox_get       avgt    9  523.149 ±  9.194
>> ms/op
>> ReifiedListBenchMark.reifiedlist_intbox_iterator  avgt    9  514.091 ± 18.357
>> ms/op
> 
> I just pushed a change that improves this (by creating a new buffer for
> a value loaded from a flattened array of unknown values and doing a bulk
> copy). Here is what I get with your benchmark:
> 
> ReifiedListBenchMark.arraylist_integer_get        avgt    9  0.246 ± 0.008
> ms/op
> ReifiedListBenchMark.arraylist_integer_iterator   avgt    9  0.248 ± 0.022
> ms/op
> ReifiedListBenchMark.reifiedlist_intbox_cursor    avgt    9  1.179 ± 0.015
> ms/op
> ReifiedListBenchMark.reifiedlist_intbox_get       avgt    9  0.715 ± 0.004
> ms/op
> ReifiedListBenchMark.reifiedlist_intbox_iterator  avgt    9  0.643 ± 0.013
> ms/op
> 
> We're likely to improve that some more with future work.
> 
> Roland.

Thanks Roland,
it's already a 500x improvement :)
I suposse that the code does not jump back into the interpreter anymore.

I will test that this week-end and try to compare the perf with installing my own inlining cache.

regards,
Rémi