[erlang-questions] [Q] Why is Erlang VM better than traditional OS like Linux?

[Guilherme Andrade]

If you'd like more detail, I propose you read upon the low-level bells
and whistles the process scheduler consists of, and it should become
more intuitive by then. No need to look at source-code; a quick web
search returns some straightforward stuff[1][2] that seems to be what
you're looking for.

Cheers,



[1]: http://www.erlang.org/euc/08/euc_smp.pdf
[2]: http://erlang.org/pipermail/erlang-questions/2001-April/003132.html


On 06/08/14 15:30, Guilherme Andrade wrote:
> Hello Ladislav,
>
> On 06/08/14 15:15, Ladislav Lenart wrote:
>> Is it because Erlang process occupies an order of magnitude less space than an
>> OS process?
>> Is it because a userspace scheduler such as Erlang VM is faster at process
>> switching? If so, why is that?
>> Is it somehow related to Erlang's share nothing philosophy? If so, how exactly?
>> Something else?
> Partially, yes. Some reasons I can think of:
>
>     - Much smaller process footprint; Erlang processes aren't visible to
> the OS, their footprint is much lighter (the context they need to keep
> track of, etc.) OS processes are traditionally heavy, even more-so than
> OS threads, which are pretty big themselves.
>
>     - By not being visible to the OS, context & execution switching
> between different processes by the scheduler doesn't have to deal with
> userland/kernelspace shenanigans (for the most part, anyway.)
>
>     - By being shared-nothing, traditional concurrency control
> mechanisms (which have considerable overhead -- specially on SMP
> machines) are not needed;
>
>     - Shooting in the dark here, but the per-process GC might also help
> on this -- concerning stability and expectable availability variations,
> anyway.
>
>
> With some oversimplifications, of course; but this is the general idea.
>
>
>
>
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-- 
Guilherme

https://www.gandrade.net/
PGP: 0x35CB8191 / 1968 5252 3901 B40F ED8A  D67A 9330 79B1 35CB 8191

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