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Cageman
08-27-2003, 03:53 AM
Hi...

Got to play around with a dual AMD Athlon 1.8GHz, 1GB ram... doing some testrenders and it showed that an Intel P4 2.4GHz is faster than the dual AMD 1.8GHz... should it be that way? Not that I should get 3.6GHz out of the AMD-machine, but sure I should get around 3GHz, and that should be faster than 2.4GHz Intel, right?

Please help... maybe there are some settings I havnīt noticed? I have set Lightwave to render with 2 threads on the dual...

gjjackson
08-27-2003, 08:32 AM
It's my understanding that LW is optimized for the Pentium's.

Cageman
08-27-2003, 12:31 PM
Yes, Iīve understood that too... :) But to confuse some more... I rendered a sequence (no motion or anything) using Screamernet (the P4 2.4 and the dual AMD). While the P4 was about 10 sek faster, the AMD clearly showed that it was using around 50-55% of the CPU. Strange speed results...

And, back into Lightwave again... rendering some polys and a particle system, and guess what... when the volumetrics were calculated, the CPU-usage dropped to around 50%... This indicates that Hypervoxels canīt be rendered with hyperthreading... :( Not good, not good... I hope that Newtek will fix this problem with version 8.

glassefx
08-27-2003, 01:16 PM
I have read from newtek that sometimes more than 2 threads are better than the number of CPU's you have. I have not done any speed tests but It seems 4 does my system justice which is a dual P3 500. Also if your running XP as your OS be sure to assign lightwave.exe (who knows aout the hub)2 processors.

Cageman
08-27-2003, 06:53 PM
Ahh... well, I have to try that later!! :) Thanks for the tip!

Extent
08-29-2003, 03:05 AM
Ahhhh so much to say in this thread. To start things off, as far as LW being optimized for Intel (as opposed to being optimized for both, which it is) see my rants in other threads :rolleyes: .

Which AMD chip are you using? Is it a 1.8Ghz chip or is it an MP1800+, there is a big difference. I have a dual MP2000+ system (which is clocked at just about 1.6 Ghz) and on the raytracing benchmark (default settings + 8 threads) I get speeds just below that of a single P4 3.4Ghz (~100sec), according to the Blanos benchmark page.

The screamernet render is not multi-threaded. In order to take advangate of dual processors with the screamer renderer you need to run two seperate instances of the program at once. The reason it says it's using 50% processing power is because the application was only running on a single processor, and if your Intel box was only running 10seconds faster compared to the AMD system which was only running at 50% capacity . . .

Some parts of the renderer are multi-threaded (NOT hyperthreaded, that's a technology that Intel chips have, not the same thing) and other parts are not. I thought that HVs were multi-threaded but I havent worked with them for a while. That is just one of the sacrifices of running a dual system, if the software is not written to specifically take advantage of it, you lose half your speed.

As far as how many threads, its true, many times running more threads than processors gives an improvement. Some scenes it's better and some its worse, the best way to find out is to do a test render at each thread setting and see which one works best. I'm lazy and I always just leave the threads at 8. I don't really know why, but it works for me *shrug*. Just as long as you have at *least* as many threads as you have processors it's fine.

And do leave thread management up to your OS. Do not think that you can manage the processors usage better than the operating system can. 2k and XP automatically take care of moving programs between the two processors (or as many as you may have) and multi threaded apps are automatically assigned to all the processors they need. They only reason you'ld need to mess with anything is if you do *not* want a program to run on a certain processor, but theres no reason to deal with that unless youre having specific troubles.

It seems you're relatively new at dual systems, I highly reccomend you check out the site and forums at 2cpu.com , they're really great and there are alot of very knowledgable people there who can help you if you're having problems.

Duals are fun :D :D :D

Cageman
08-29-2003, 05:00 AM
Extent:

Here is the relevant hardware specs:

Motherboard: MSI K7D Master-L Moderkort Socket A, MP
AMD760MPX, Dual, ATA100, ATX 266MHz FSB

Processors: AMD Athlon MP2200+ 1.8 GHz 266 MHz bus
Socket A (Thoroughbred) processor

1GB ram.

OS: Windows 2000 Pro

Well, itīs the first time Iīve ever built a dual system from scratch, though I have used the other dualsystem at school. I wouldīt dare to touch any settings regarding how the OS handles the CPU:s, but I just thought that MAYBE there were some settings in Lightwave that I hadnīt checked. Ohh... according to another thread, LWSN does support multithread, though itīs not a good idea to use it, as many plugins/shaders etc could crash.

And some programs, like TMPGEnc doesnīt automaticly use both CPU:s; like Lightwave I had to set it to use multithread. Here are some statistics from some testrenders I made:

Testmachines:
AMD Athlon MP 1.8GHz (Dual) (Thoroughbred), 1GB ram (AMD-MP)
AMD Athlon XP 1.6GHz, (Thoroughbred), 512MB ram (AMD-XP)

640x480:
AMD-MP = 5m 42s (1 Thread)
AMD-MP = 3m 25s (2 Threads)
AMD-MP = 3m 31s (4 Threads)
AMD-MP = 3m 32s (8 Threads)
AMD-XP = 7m 28s

I have attached the rendered picture...

Iīve bookmarked the URL.. seems that it may be quite useful... =)

And again, thanks alot for all the suggestions!!

Cageman
08-29-2003, 05:05 AM
Originally posted by Extent
I have a dual MP2000+ system (which is clocked at just about 1.6 Ghz) and on the raytracing benchmark (default settings + 8 threads) I get speeds just below that of a single P4 3.4Ghz (~100sec), according to the Blanos benchmark page.


Sounds interresting! Could you be more specific about that Raytracing benchmark? What is it? How/where can I find it?

Extent
08-29-2003, 07:14 PM
It's the raytrace benchmark scene that installs with the rest of the sample scenes that come with LW.

Some apps (like LW and TMpeg like you said) you have to turn multi-threading on, but once it's on in the app the OS will take care of assigning them to processors.


I just read the thread where they said Snet is multi-threaded, I'll have to play with it now. It is strange that plugins cause it to crash tho, since the native LW renderer works fine in multi mode regardless of how the plugins are written. But it's not exactly the same code who knows.

Cageman
11-20-2003, 08:16 AM
Another problem here...

Sometimes when starting one screamernet node on the dual machine, it takes 100% processing power, when it really should just use 50-55%.. how can this happen? I thought that LWSN by default is single-threaded, and I have not touched any settings...

Please help...