OS scheduling vs. VM scheduling

Ulf Wiger <>
Thu Jan 22 15:05:28 CET 2004


On Thu, 22 Jan 2004 14:49:01 +0100, Joachim Durchholz 
<> wrote:

> Hi all,
>
> When leafing through old messages, I hit on Vance Shipley's old "One 
> Million Processes" thread, and my mind made a connection to a recent 
> information snippet.
>
> The new Linux 2.6 kernels have been reported to spawn processes at a
> rate of 100.000 within a relatively short time (seconds or very few
> minutes).

Yes, I remember that too.
Note that they're talking about threads, i.e. just creating
a context in shared memory. Erlang "threads" do not share
memory (conceptually, even if they do in reality). This is
something to think about if one wants to share the memory
space with other languages -- Erlang processes _behave_ as if
their memory is protected and separate from others.

Another implication is that the VM has to be made thread-safe.
It is not so today. The upside is that it would become possible
to take advantage of multipro architectures in a wholly different
way than today.

The issues are well covered in the following document:
http://www.erlang.se/publications/xjobb/0089-hedqvist.pdf
("A Parallel and Multi-threaded Erlang Implementation" by
Pekka Hedqvist)

The details that appear to have changed since then are the
number of threads that can be created and the cost of creating
them (but basically only on Linux.)

/Uffe
-- 
Ulf Wiger, Senior System Architect
EAB/UPD/S



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