Re: [Caml-list] Ocaml implementation and low level details

[Konstantin Tcholokachvili <tcholoka@gmail.com>]

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Thank you for these infos, I will consider which solution fits the best with
my project: make a trade off, find a more suitable ML implementation or
stay  (sadly) with C.

Konstantin Tcholokachvili

2010/1/28 Samuel Thibault <samuel.thibault@inria.fr>

> Konstantin Tcholokachvili, le Thu 28 Jan 2010 14:35:50 +0100, a écrit :
> >     > - Also need I disable Ocaml theading subsystem? (Obviously yes, but
> are
> >     there
> >     > some limitations?)
> >
> >     IIRC we just needed to port it.
> >
> >
> > OK but as there is a giant lock (as I heard), I'm afraid that the
> > multithreading subsystem of my kernel will suffer from that.
> > Am I correct?
>
> Ah, the kernel can't be running concurrently, yes. Just like Linux 2.0
> was working, actually.
>
> >     > Are there other important considerations to take?
> >
> >     In my memory, mostly the direct access to some kinds of memory, like
> the
> >     video memory: we faked a string with the -unsafe option to get
> efficient
> >     direct access.
> >
> > So must I also make tricks to have DMA acess?
>
> Yes, unless you get hooks into the caml runtime to be notified of
> garbage collection, to update pointers & such.
>
> >     > Do you think that Ocaml is suitable for OS coding (I''m using C
> now).
> >
> >     It's much better for all the programmability & safety reasons. Funk
> >     showed that it is possible. Performance should be quite good.  Now
> the
> >     pragmatic answer would be that Linux already works quite well and has
> >     all the drivers we need, while yet another new kernel would have to
> >     rewrite them all. And about performance, when you see how much Linux
> >     people care about tiny details in their lock implementation etc., a
> caml
> >     implementation wouldn't suit that.
> >
> > My goal isn't to have a kenel portable across many platforms but only
> > to some kind of hardware.  It's a hobby project.
>
> Ok, then you can probably start with the current funk testbed :)
>
> > Why caml's implementation wouldn't be suitable? Because of the giant lock
> as I
> > mentioned before?
>
> Because you do not have as much control over e.g. data alignment & such
> as in C. Linux people spend quite some time fine-tuning such small
> details and get performance benefits.
>
> Samuel
>

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