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Ger <ger### [at] hotmail com> wrote:
> That would be?
You are basically saying that rendering two benchmarks using two
threads should be faster than rendering one benchmark using one thread.
This is, of course, just flawed thinking. There's no way of getting
two benchmarks rendered faster even when using two distinct processors
than one benchmark in one processor.
What he is saying is that rendering two benchmars at the same time
gets rendered 25% faster than rendering first one benchmark and then
the other. The end result of both test is identical, but the first
test produced it 25% faster.
--
plane{-x+y,-1pigment{bozo color_map{[0rgb x][1rgb x+y]}turbulence 1}}
sphere{0,2pigment{rgbt 1}interior{media{emission 1density{spherical
density_map{[0rgb 0][.5rgb<1,.5>][1rgb 1]}turbulence.9}}}scale
<1,1,3>hollow}text{ttf"timrom""Warp".1,0translate<-1,-.1,2>}// - Warp -
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Chris Jeppesen wrote:
> Given: One Pentium 4 with hyperthreading (2 virtual processors)
> Find: Does running two instances of POV-Ray make sense?
Your testing is very interesting.
How about running the exact same tests with hyperthreading turned OFF?
So you'll have 4 results on the exact same hardware
single - with hyperthreading
double - with hyperthreading
single - no hyperthreading
double - no hyperthreading
It would be interesting to see the difference between the hyperthreading
and non-hyperthreading results.
This might help show what you have found through your testing.
Tom
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On Friday 23 July 2004 14:49, Warp wrote :
> Ger <ger### [at] hotmailcom> wrote:
>> That would be?
>
> You are basically saying that rendering two benchmarks using two
> threads should be faster than rendering one benchmark using one thread.
Either I said it wrong or you understood wrong.
Rendering 1 image on a computer with more then one processor will always be
faster then rendering the same on a single(non-hyper) processor.
What I was (tried to) pointing out that the total time spend on a single
pixel in the single instance is less then in the dual instance because of
the non_pov stuff going on.
>
> This is, of course, just flawed thinking. There's no way of getting
> two benchmarks rendered faster even when using two distinct processors
> than one benchmark in one processor.
>
I never said it would. (and if then I definitely need to rephrase that)
> What he is saying is that rendering two benchmars at the same time
> gets rendered 25% faster than rendering first one benchmark and then
> the other. The end result of both test is identical, but the first
> test produced it 25% faster.
>
Sure, I understood that. All I pointed out is that the cpu-time/pixel in the
single instance is less. Otoh, making a statement like this on a
hyperthreading processor is dodgy at best because a hyperthreading
processor is not nearly the same as two distinct processors.
--
Ger
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Ger <ger### [at] hotmailcom> wrote:
> Sure, I understood that. All I pointed out is that the cpu-time/pixel in the
> single instance is less.
And that's where you are wrong. You need to count the total number
of pixels calculated and divide it by the time it took to calculate
all those pixels. In this case it took 56 (or whaver it was) minutes
to render 2xbenchmark pixels.
--
#macro M(A,N,D,L)plane{-z,-9pigment{mandel L*9translate N color_map{[0rgb x]
[1rgb 9]}scale<D,D*3D>*1e3}rotate y*A*8}#end M(-3<1.206434.28623>70,7)M(
-1<.7438.1795>1,20)M(1<.77595.13699>30,20)M(3<.75923.07145>80,99)// - Warp -
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On Friday 23 July 2004 19:40, Warp wrote :
> Ger <ger### [at] hotmailcom> wrote:
>> Sure, I understood that. All I pointed out is that the cpu-time/pixel in
>> the single instance is less.
>
> And that's where you are wrong. You need to count the total number
> of pixels calculated and divide it by the time it took to calculate
> all those pixels. In this case it took 56 (or whaver it was) minutes
> to render 2xbenchmark pixels.
>
Difference is that you are talking about "total computer" time, I was
talking about "per processor" time.
--
Ger
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> Difference is that you are talking about "total computer" time, I was
> talking about "per processor" time.
... which is the same since there's a single CPU in the computer :-)
- NC
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On Friday 23 July 2004 21:02, Nicolas Calimet wrote :
>> Difference is that you are talking about "total computer" time, I was
>> talking about "per processor" time.
>
> ... which is the same since there's a single CPU in the computer :-)
>
> - NC
Not entirely true. It's not the same as a very fast Pentium II. Nor is it a
very fast dual Pentium II. But it's enough of a dual proc to make a
difference when running two parallel renders.
--
Ger
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Ger <ger### [at] hotmailcom> wrote:
> Difference is that you are talking about "total computer" time, I was
> talking about "per processor" time.
Who cares about the "per processor" time?
People want their renders to finish as fast as possible.
--
#macro N(D)#if(D>99)cylinder{M()#local D=div(D,104);M().5,2pigment{rgb M()}}
N(D)#end#end#macro M()<mod(D,13)-6mod(div(D,13)8)-3,10>#end blob{
N(11117333955)N(4254934330)N(3900569407)N(7382340)N(3358)N(970)}// - Warp -
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On Saturday 24 July 2004 10:00, Warp wrote :
> Ger <ger### [at] hotmailcom> wrote:
>> Difference is that you are talking about "total computer" time, I was
>> talking about "per processor" time.
>
> Who cares about the "per processor" time?
> People want their renders to finish as fast as possible.
>
Okay, fair enough :)
--
Ger
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Tom Austin nous apporta ses lumieres ainsi en ce 23/07/2004 09:03... :
> Chris Jeppesen wrote:
>
>> Given: One Pentium 4 with hyperthreading (2 virtual processors)
>> Find: Does running two instances of POV-Ray make sense?
>
>
> Your testing is very interesting.
>
> How about running the exact same tests with hyperthreading turned OFF?
>
> So you'll have 4 results on the exact same hardware
> single - with hyperthreading
> double - with hyperthreading
> single - no hyperthreading
> double - no hyperthreading
>
> It would be interesting to see the difference between the
> hyperthreading and non-hyperthreading results.
>
> This might help show what you have found through your testing.
>
>
>
> Tom
>
I saw some P4 benchmarks using the same CPU with and without
hyperthreading enabled. Most where SLOWER when using hyperthreading.
Sory, I don't remember where I saw those.
Alain
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