In povray.general Chris Cason <nospam@noemail> wrote:
:> Even simpler is to send frames out to different systems.

: You don't have a clue what you're talking about. Come back when you understand
: the subject.

  Please try to understand that it is not so easy to know the difficulties
of multithreading and multitasking unless you have studied it or tried to
make lots of programs using it.
  I didn't have a clue about multithreading and multitasking (and their
problems) until I had several courses about the matter here (Tampere university
of technology).
  A layman can easily think that it's just a piece of cake to make
multitasked systems and multithreaded programs. It's only when you try to
do it or when you are taught about it that you realize how problematic it
really is. Some problems are so deep, that even the most modern science have
not solved them in a fool-proof manner.
  One could think that if it's so problematic, how come there are countless
operating systems and programs using it without problems?
  Operating systems have more than 30 years of experience about multitasking
behind them and they use well-known algorithms. These algorithms are often
extremely complicated, specially if the OS tries to achieve the multitasking
effectively, without too much overhead (multitasking is _never_ free; it
always consumes some resources). This is the reason why some systems don't
have multitasking at all and some others have only extremely poor versions
of them.
  A multithreaded program is not any luckier (if anything, it's the other
way around, ie. it can have even more problems). There are very serious
and complicated problems here, like mutual exclusion problems, communication
(between threads) problems, problems about sharing of resources, and so on.
Some operating systems offer system tools for these tasks (like semaphores,
monitors, etc), others don't.
  The big problem about these is that they are incredibly malicious. You can
have a mutual exclusion bug in your program which doesn't happen to you no
matter how many test runs you make. However when thousands of people start
to use the program, the bug can arise.
  These mutual exclusion (and other similar) bugs usually happen in only
certain conditions. These conditions are usually extremely rare and extremely
hard to reproduce (you'll have to reproduce the entire series of events that
lead to that bug, and this can be near to impossible since it may depend
on what the operating system was doing at that exact time).
  There's one adjective to describe this type of behaviour: Non-deterministic.

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

Post a reply to this message

"Warp" <war### [at] tagpovrayorg> wrote in message
news:395b1a0a@news.povray.org...
>   Please try to understand that it is not so easy to know the difficulties
> of multithreading and multitasking unless you have studied it or tried to
> make lots of programs using it.
>...
>   A layman can easily think that it's just a piece of cake to make
> multitasked systems and multithreaded programs.

<dumb>
Gosh, you lot do try and complicate things. Multi-tasking is easy - you just
wire up a load of CPUs in series. Alternatively, if you wish your system to
go longer without crashing, you can wire them up in parallel.
</dumb>

Post a reply to this message

Warp wrote:
> 
>   I can make a program that completely steals all the CPU time in windows.

But not in NT.

>   I don't know about win2k or NT.

Aha.

Markus

Post a reply to this message

> It is possible to render a portion of an image, but getting the images
> tiled without discontinuities is a problem. If you distribute parts of
> an image to different machines this way, features like radiosity,
> antialiasing, etc can produce a "tiles" effect, like a mosaiac
> photograph.

couldn't this be solved by using overlapping tiles?

Rick

Post a reply to this message

In povray.general Chris Huff <chr### [at] maccom> wrote:
: It is possible to render a portion of an image, but getting the images 
: tiled without discontinuities is a problem. If you distribute parts of 
: an image to different machines this way, features like radiosity, 
: antialiasing, etc can produce a "tiles" effect, like a mosaiac 
: photograph.

  So far radiosity is the only source of problems. Antialiasing is not
a problem.

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

Post a reply to this message

On 28 Jun 2000 23:41:08 -0400, daishi wrote:
>ron### [at] povrayorg (Ron Parker) wrote in
><slr### [at] linuxparkerrfwicom>: 
>
>>On 28 Jun 2000 23:35:08 -0400, daishi wrote:
>>>if I'm not mistaken there is a way to save the radisoisty file in
>>>pov-ray. would making sure each time you did radisoity you saved the
>>>file work around the problem?
>>
>>For continued renders, yes.  I'll leave the question of whether it would
>>help parallel rendering as an exercise for the reader.
>>
>
>me thinks I'll try this tomorrow....

Well, that confirms my suspicions.  The answer to that question does not
require research, just a little (very little) thought.

(hint: if you don't have the radiosity cache you need for line 10 until you
finish line 9, how are you going to render line 10 in parallel with line 1?)

-- 
Ron Parker   http://www2.fwi.com/~parkerr/traces.html
My opinions.  Mine.  Not anyone else's.

Post a reply to this message

"Warp" <war### [at] tagpovrayorg> wrote in message news:395b4663@news.povray.org...
| In povray.general Chris Huff <chr### [at] maccom> wrote:
| : It is possible to render a portion of an image, but getting the images
| : tiled without discontinuities is a problem. If you distribute parts of
| : an image to different machines this way, features like radiosity,
| : antialiasing, etc can produce a "tiles" effect, like a mosaiac
| : photograph.
|
|   So far radiosity is the only source of problems. Antialiasing is not
| a problem.

Radiosity sampling would be nice for partial renders, even if POV-Ray were to
redo the entire image in mosaic preview before doing the selected region.
Guess that goes without saying.

Bob

Post a reply to this message

In povray.general Bob Hughes <per### [at] aolcom?subject=pov-news:> wrote:
: Radiosity sampling would be nice for partial renders, even if POV-Ray were to
: redo the entire image in mosaic preview before doing the selected region.
: Guess that goes without saying.

  This is only supposing that it will not calculate any new radiosity samples
in the final pass.

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

Post a reply to this message

tom### [at] tomandluf9couk (Tom Melly) wrote in <395b19de$1@news.povray.org>:

>"lavender" <lav### [at] hotmailcom> wrote in message
>news:8F617F84Elavendersmith@204.213.191.228...
>> Computers have been networked not for a long time. The internet is
>> almost .....
>
>Hmm, I smell a rat - or am I just being naive in thinking that no one
>could be this idiotic and insulting accidentally?
>
>> ... As for money they can talk to me about that.
>
>I hereby appoint myself financial director in the lavender/POV-team
>endevour. Send me money. Initially, it will be spent on a new Pentium
>III PC for myself, as I wish to render all contracts with radiosity and
>photons on iso-surface paper.
>
>

I am not sure what you are trying to say with this but I will reply to the 
buttom part.

Why do you not have enough money to buy you a new PIII system? Email this 
back and I will explain! Not in this form.

Post a reply to this message

"lavender" <lav### [at] hotmailcom> wrote in message
news:8F6276DAClavendersmith@204.213.191.228...
> tom### [at] tomandluf9couk (Tom Melly) wrote in <395b19de$1@news.povray.org>:
>
> >"lavender" <lav### [at] hotmailcom> wrote in message
> >news:8F617F84Elavendersmith@204.213.191.228...
> >> Computers have been networked not for a long time. The internet is
> >> almost .....
> >
> >Hmm, I smell a rat - or am I just being naive in thinking that no one
> >could be this idiotic and insulting accidentally?
> >
> >> ... As for money they can talk to me about that.
> >
> >I hereby appoint myself financial director in the lavender/POV-team
> >endevour. Send me money. Initially, it will be spent on a new Pentium
> >III PC for myself, as I wish to render all contracts with radiosity and
> >photons on iso-surface paper.
> >
> >
>
> I am not sure what you are trying to say with this but I will reply to the
> buttom part.

but tom what?

>
> Why do you not have enough money to buy you a new PIII system? Email this
> back and I will explain! Not in this form.

What form would you like to use? (recognisable English would be a start).

Post a reply to this message