[erlang-questions] Ets read concurrency tweak

[Chandru]

Hi,

You might want to read this to get some insights.

<http://www.researchgate.net/profile/Konstantinos_Sagonas/publication/262172496_On_the_scalability_of_the_Erlang_term_storage/links/53f3a22f0cf2155be351bc3b.pdf?origin=publication_detail>
<http://www.researchgate.net/profile/Konstantinos_Sagonas/publication/262172496_On_the_scalability_of_the_Erlang_term_storage/links/53f3a22f0cf2155be351bc3b.pdf?origin=publication_detail>
http://www.researchgate.net/profile/Konstantinos_Sagonas/publication/262172496_On_the_scalability_of_the_Erlang_term_storage/links/53f3a22f0cf2155be351bc3b.pdf?origin=publication_detail

cheers,
Chandru


On 15 May 2015 at 12:00, Viacheslav V. Kovalev <kovyl2404@REDACTED> wrote:

> I've added writer process to my test. It perfoms random write per each
> 100 ms. Implementation is here:
> https://gist.github.com/kovyl2404/622a9908c4e8a2abc214
>
> There is example of run on 8-core machine.
>
> 29> ets_read_concurrency:analyze(WithoutWriter).
> [{{procs,1},{percent,-8.998057178933019}},
>  {{procs,2},{percent,1.474232611754453}},
>  {{procs,4},{percent,-0.4318193657099243}},
>  {{procs,8},{percent,4.796912026714365}},
>  {{procs,16},{percent,4.926194326111598}},
>  {{procs,32},{percent,7.4091491628647805}},
>  {{procs,64},{percent,6.7226404897426315}},
>  {{procs,128},{percent,7.129140726319386}},
>  {{procs,256},{percent,-28.200373148451757}},
>  {{procs,512},{percent,10.229583687247757}},
>  {{procs,1024},{percent,25.824989572270635}}]
> 30> ets_read_concurrency:analyze(WithWriter).
> [{{procs,1},{percent,-9.233383915316411}},
>  {{procs,2},{percent,1.3554058972355476}},
>  {{procs,4},{percent,-1.3437122387165232}},
>  {{procs,8},{percent,0.3944371727018411}},
>  {{procs,16},{percent,21.719493229803017}},
>  {{procs,32},{percent,-26.32711009412866}},
>  {{procs,64},{percent,11.577461884371825}},
>  {{procs,128},{percent,19.608517106505893}},
>  {{procs,256},{percent,11.362311552960543}},
>  {{procs,512},{percent,20.935963863004808}},
>  {{procs,1024},{percent,22.512472513575506}}]
>
> Where percent calculated as `(NonTweakedTime - TweakedTime)/NonTweaked*100`
>
> Tweaked table shows stable performance advantage either with or
> without writer process. I think I was wrong when interpreted former
> results, but frankly I expected to see more drastic changes. Again, I
> don't know how to interpret this artifacts:
>
> {{procs,256},{percent,-28.200373148451757}}. %% WithoutWriter
> {{procs,32},{percent,-26.32711009412866}}. %% WithWriter
>
> Is this just statistical error or something else?
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