Re: General question about GNUStep

[Simeon Mitev]

Is it not going about compiler possibilities to optimize the code using 
hyper threading? OpenMP is a specification trying to get a standard for 
such things, I hope, I have it not totally misunderstood.

Is ObjC compiler just an extension to the common GNU C compiler (100% 
compatible) or it is a standalone realization which can also compile C code.

In example:

# pragma ..... - explicitly enabling hyper threading
for( int i=0; i<n; i++)
  a[i] = b[i]*x + c[i]*y;

Lets say n is supposed to have the value 100 000.

When you compile this enabling hyper threading the compiler can prepare 
code which will execute at this point lets say 10 threads. Each thread 
will do the same but for different scopes for i:

T1: i = 0..9999;
T2: i = 100000 ... 199999;
T3: ...
T10 i = 90000  ... 999999;

At the end the a array will be calculated for ways shorter time than one 
thread with 100 000 iterations, because each processor core will take 
part of this calculation.

GNU gcc (4.3.2) has already an option and you can compile with -fopenmp .

My question was: Does ObjC compiler handle also the same feature or it 
does not?


> Hi,
>
> On Thu, Aug 27, 2009 at 9:12 AM, Simeon Mitev<develop@paymobile.me> wrote:
> > Of course, I meant native hyper threading support :)
> >
> > > Nice Nicola,
> > >
> > > Thank you for the good presentation!
> > >
> > > I have got answers for some of my questions. What I am still interested in
> > > is multi threading support in objC compiler and runtime. While the server
> > > application will run on unix with 2 quad core processors I will definitively
> > > need to use multi threading to get a real benefit from the hardware. In C++
> > > I can use also openMP (http://openmp.org/wp/) in example. Thoughts ?
>
> OpenMP is for shared memory multiprocessing, not just multithreading.
> It's also available in C, so you can directly use it in Objective-C if
> you want...
>
> Objective-C and GNUstep do support multithreading (see NSThread). Have
> a look also at Etoile's EtoileThread implementation,
> http://svn.gna.org/viewcvs/etoile/trunk/Etoile/Frameworks/EtoileFoundation/EtoileThread/
> (which let you trivially run an object in a separate thread and
> implements futures for returned values,
> http://en.wikipedia.org/wiki/Futures_and_promises), it's _really_
> nice.
>
> > > > > > It looks like I will go back to C++ or Java for the server,
> > > > > Why?  Objective-C is much better than either... it's a very good server
> > > > > solution (C++ is too inflexible and Java is slow/clumsy).
> > > > Yes! :-)
> > > >
> > > > Simeon,
> > > >
> > > > you can check my  "Building server applications using Objective-C and
> > > > GNUstep" Fosdem 2009 presentation on
> > > >
> > > >  http://www.gnustep.it/nicola/Presentations/index.html
> > > >
> > > > if you're interested in a quick summary overview.  If you're starting
> > > > from scratch, and are using Objective-C on the client anyway, it's really
> > > > worth for you to consider writing your server in Objective-C too - even if
> > > > they talk to each other using a custom, language-independent protocol. ;-)
> > > >
> > > > Anyway, whatever you choose to do, good luck with your project. :-)
> > > >
> > > > Thanks
> > > >
> > > >
> > > >
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> > >
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