[erlang-questions] Dirty NIF - classifying as CPU or I/O bound

[Steve Vinoski]

On Sun, Oct 14, 2018 at 10:47 AM Jesper Louis Andersen <
jesper.louis.andersen@REDACTED> wrote:

> On Sun, Oct 14, 2018 at 2:42 PM Roger Lipscombe <roger@REDACTED>
> wrote:
>
>> If I *don't know* whether the job is going to be CPU bound or I/O bound
>> (it executes arbitrary code provided by a third party), am I safest to just
>> classify the dirty job as CPU-bound? Or is this warning hinting at a
>> disaster of biblical proportions[1] if I even *think* about fudging the
>> classification?
>>
>>
> Either classification risks being wrong, so you can't really do any of
> them safely. The two classifications exist because IO resources and CPU
> resources tend to orthogonally consumed: If we have many IO bound jobs, we
> can still run CPU bound jobs and vice versa. But if you don't know what
> kind of job you are looking at a priori, you have no way to classify it
> correctly.
>
> You *could* run it with some kind of sandbox environment and then make a
> guess: If it were IO bound last time, it probably still is. But this is
> more involved.
>

I agree with Jesper, and I'll add that to the best of my knowledge no
disaster of biblical proportions will happen if you guess incorrectly.

--steve
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