[erlang-questions] Erlang Cost Model

Jesper Louis Andersen jesper.louis.andersen@REDACTED
Wed Sep 16 20:43:23 CEST 2015


On Wed, Sep 16, 2015 at 5:03 PM, Eric des Courtis <
eric.des.courtis@REDACTED> wrote:

> For example Python has this cost model
> http://scripts.mit.edu/~6.006/fall07/wiki/index.php?title=Python_Cost_Model
>  .
>

The cost model has to be evaluated against memory read times. An
instruction which is in the L1 cache or perhaps even in the register bank
is almost never going to give a realistic view of runtimes. So beware of
simply summing these things. You need to plot the frequency distribution
function to guarantee a stable number, and you should also plot the curve
as data grows. Often you have cliffs where you start hitting  L3 or DRAM.

Also, processor intercommunication tend to be "costly". But if you want to
get more than a single core doing work, you need to move work to other
cores.


-- 
J.
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