I'm going to need to buy a new computer soon, and I'm wondering how well pov
will run on a dual processor G4 500 mhz power mac. Are they as great as
apple claims or should I just stick with pc's?

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Ed Kaiser wrote:
> 
> I'm going to need to buy a new computer soon, and I'm wondering how well pov
> will run on a dual processor G4 500 mhz power mac. Are they as great as
> apple claims or should I just stick with pc's?

POV-Ray isn't multi-threaded, so SMP may not help you much.  There are
unofficial parallel versions out there, but they mostly require Unix. 
If you're looking to run Linux PPC, MkLinux, Yellow Dog Linux, NetBSD,
etc., you should be OK.  If you're planning on sticking with MacOS, a
second CPU isn't going to do much good (though they may be able to work
on OS X someday).

Thorsten, correct me if I'm wrong.

-Mark Gordon

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I use SMP on NT for rendering animations.  First I start two copies of
the program and set the affinity to only one CPU for each.  Then I'll
set one to render the first half of the animation and the other to do
the rest.  The rendering takes half as long.

-Mike

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Mike wrote:
> 
> I use SMP on NT for rendering animations.  First I start two copies of
> the program and set the affinity to only one CPU for each.  Then I'll
> set one to render the first half of the animation and the other to do
> the rest.  The rendering takes half as long.
> 
> -Mike

I do the same thing.  Linux users don't have to worry about affinity
because the scheduler has a concept of "preferred processor" which
is the cpu that previously ran the thread.  So a render will "stick"
to one cpu over the other.  NT, as BillG would say, "that is totally 
random".

NT's scheduler is so dumb (how dumb is it?) that if i lock a render
to a CPU and then run another program; it will preempt the render
50% of the time, leaving the other CPU 50% idle as it flip-flops
between the two CPUs.

dik

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Mark Gordon <mtg### [at] mailbagcom> wrote:
: If you're planning on sticking with MacOS, a
: second CPU isn't going to do much good

  Well, it's not exactly true.
  Povray runs in one processor, but you still have to other one free for
whatever else you want. This means that povray will really run in the
background without interfering whatever else you are doing because you are
using the other free processor.

-- 
main(i,_){for(_?--i,main(i+2,"FhhQHFIJD|FQTITFN]zRFHhhTBFHhhTBFysdB"[i]
):_;i&&_>1;printf("%s",_-70?_&1?"[]":" ":(_=0,"\n")),_/=2);} /*- Warp -*/

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In article <398f77c2@news.povray.org> , "Ed Kaiser" <eka### [at] camdentdsnet>
wrote:

> I'm going to need to buy a new computer soon, and I'm wondering how well pov
> will run on a dual processor G4 500 mhz power mac. Are they as great as
> apple claims or should I just stick with pc's?

As the others already said, POV-Ray does not render faster on
multiprocessors systems right now.  As for other applications on Mac OS, it
depends on what else you want to do.

If you are only up for the fastest system to render with POV-Ray, a 1 GHz
Athlon will probably be the fastest (and, contrary to the 1 GHz Pentium, you
will be able to buy it ;-)

If you are going to do a lot of work with Photoshop, Premiere or a few other
applications supporting multiprocessing on Macs, go for the Mac.

If you are going to do "average" office work, editing text, websites, and
use POV-Ray occasionally, and you like the Mac OS, go for the Mac.

In general, except if you use POV-Ray or a few other processor intensive
applications (i.e. 3D games) exclusively, any system, even an iMac will
offer more performance than you will need.  And it will cost less :-)


    Thorsten


____________________________________________________
Thorsten Froehlich
e-mail: mac### [at] povrayorg

I am a member of the POV-Ray Team.
Visit POV-Ray on the web: http://mac.povray.org

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In article <398fd4a9@news.povray.org> , Warp <war### [at] tagpovrayorg>  wrote:

> : If you're planning on sticking with MacOS, a
> : second CPU isn't going to do much good
>
>   Well, it's not exactly true.
>   Povray runs in one processor, but you still have to other one free for
> whatever else you want. This means that povray will really run in the
> background without interfering whatever else you are doing because you are
> using the other free processor.

No, this is not the case when running Mac OS (it will be the case once Mac
OS X is out early next year).  Mac OS still uses co-operate multitasking and
some parts of the OS are not even reentrant - especially most of the GUI.
The benefit is that even applications written in 1984 which ran on the
original Macintosh will run today (and as there is no Y2K problem on Mac OS,
they still run as expected!).  If this kind of backward compatibility is
really necessary is another issue, but it is up to Apple...

Only applications requesting to run on a second processor will actually gain
any benefit on Mac OS.  Making exceptionally good use of this are Adobe
products (Photoshop, Premiere and AfterEffects, as far as I know) and a few
other applications.  A list is surely available somewhere on the Apple
website.

Of course, it is always possible to install Linux PPC on a dual-G4 Mac, and
the multiprocessing world is 'normal' again :-)


     Thorsten


____________________________________________________
Thorsten Froehlich, Duisburg, Germany
e-mail: tho### [at] trfde

Visit POV-Ray on the web: http://mac.povray.org

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In article <398F82A1.B472D0C3@aol.com> , Mike <Ama### [at] aolcom>  wrote:

> I use SMP on NT for rendering animations.  First I start two copies of
> the program and set the affinity to only one CPU for each.  Then I'll
> set one to render the first half of the animation and the other to do
> the rest.  The rendering takes half as long.

This will not work when running Mac OS, multiprocessing works 'different'
there...


     Thorsten


____________________________________________________
Thorsten Froehlich, Duisburg, Germany
e-mail: tho### [at] trfde

Visit POV-Ray on the web: http://mac.povray.org

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In article <398ff0ae@news.povray.org>, "Thorsten Froehlich" 
<tho### [at] trfde> wrote:

> No, this is not the case when running Mac OS (it will be the case 
> once Mac OS X is out early next year).  Mac OS still uses co-operate 
> multitasking...
...snip...

As I understand it, the problem isn't the cooperative multitasking, it 
is the way the multiprocessing is done. Currently, the Mac OS doesn't do 
SMP(symmetric multiprocessing), it is assymetric. I think the OS gets 
one CPU, and applications run on the second, unless they are 
specifically designed to handle multiple CPUs(PhotoShop, for example, 
can use both CPUs).


> Of course, it is always possible to install Linux PPC on a dual-G4 
> Mac, and the multiprocessing world is 'normal' again :-)

Or you could just wait until the OS X public beta is released...

-- 
Christopher James Huff - Personal e-mail: chr### [at] maccom
TAG(Technical Assistance Group) e-mail: chr### [at] tagpovrayorg
Personal Web page: http://homepage.mac.com/chrishuff/
TAG Web page: http://tag.povray.org/

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In article <chrishuff-69ABA9.07274608082000@news.povray.org> , Chris Huff 
<chr### [at] maccom>  wrote:

> As I understand it, the problem isn't the cooperative multitasking, it
> is the way the multiprocessing is done. Currently, the Mac OS doesn't do
> SMP(symmetric multiprocessing), it is assymetric.

Well, the fact that it is asymmetric is a consequence of the co-operative
OS. To put it in strong words, the OS is to root of all evil.  Its
co-operative nature, due to its age and original system, is causing all
kinds of problems today. Nevertheless, it is remarkably stable compared to
systems having pre-emptive multitasking and memory protection...

> I think the OS gets
> one CPU, and applications run on the second, unless they are
> specifically designed to handle multiple CPUs(PhotoShop, for example,
> can use both CPUs).

The second CPU is not used at all if the an application does not use the
so-called "Multiprocessing API" to create multiple threads.  While the full
detail of the implementation of this is not documented by Apple, the
documentation makes clear that the OS will only run on the "first" processor
together with all other applications. Only when an application creates
pre-emptive threads using the MP-API, the second CPU will be available to
those threads.  Additionally, the OS will share the first CPU with those
threads.  Due to the support for co-operative multitasking is is still
possible for an application to lock both CPUs by creating a single
pre-emptive thread on the second CPU and use the first CPU exclusively via
co-operative scheduling.

Currently an application using the pre-emptive threads may only call certain
reentrant parts of the Mac OS, in particular the file and device manager
(requires Mac OS 9 then, I think).  Every other system function has to be
called using a remote-procedure call  mechanism, which then forces all
threads to hold and execute the function on the CPU running the Mac OS.

So, also not tested, it should be possible to run POV-Ray Mac (3.5) in the
same way the Windows version does.  One CPU (the second one in this case)
would do the rendering, and the first one runs the editor and all other
applications.  With such a version of POV-Ray Mac, it should also be
possible to run it twice, and use both processors.

Unfortunately, this is all theoretical, and without a dual processor Mac, I
am not going to attempt to write such a version.  Maybe the university I
attend will get a few dual G4 Macs soon, so I can at least debug it...


    Thorsten


____________________________________________________
Thorsten Froehlich, Duisburg, Germany
e-mail: tho### [at] trfde

Visit POV-Ray on the web: http://mac.povray.org

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