PDA

View Full Version : 64 bit - No performance gain?



Remoc
03-31-2009, 03:57 AM
Hello I am Remoc

I have a Q6600 Quadcore computer with 4Gb of RAM.
On which I had Vista Home Premium 32 bit, and Lightwave 9.6 (32bit).
I set my segment memory to the max. ( 2000 MB )

I made a scene of a stadium with one light (DP Infinit plugin32) and used
classic camera with monte carlo radiosity on.
This was my reference render scene. It took 14m 4s (844 sec.) to render a frame.

Then I formated my drive, and installed vista 64.
And install the 64 bit Lightwave 9.6 and installed DP Lights 64 plugin.
I opened my previous scene and rendered.
It took 14m 18s (857.8) to render. Thats 14 sec. longer.

I know 64 bit allows higher use of RAM, but my scenes barely ever take up more then 1 gig in memory. But somehow I thought 64 bit processing would be faster.
With no real gains I only lose potential use of plugins not 64 bit compatible.

Am I wrong?

sammael
03-31-2009, 04:02 AM
You can install both 64 and 32 bit versions on Vista 64, youll notice performance increace in polygon heavy scenes with the 64 bit version.

biliousfrog
03-31-2009, 04:14 AM
You won't notice much difference with 4gb RAM although you should find that scenes with large textures or high-res renders will be faster...or will actually render where they wouldn't before. The biggest impact on render speed is the CPU not memory (unless you run out of it).

Remoc
03-31-2009, 06:11 AM
So basically the 64 bit code isn't faster or more efficient ect.
The reason I thought it might be is because the CPU is 64 bit.
So I assumed that using a 64 bit OS meant it could process 64 bits
per CPU cycle ( or something like that ).

Well a bit disappointing.

biliousfrog
03-31-2009, 06:33 AM
In general, 64bit applications running on a 64bit system tend to be a bit faster but the real benefits are in being able to address more memory. RAM is used for storing data so the ability to store more data by using more RAM will makes things faster but only if RAM was the bottleneck in the first place. I good example is rendering for large format printing which might not even start on a 32bit system but wouldn't be a problem with 64bit and 8gb RAM.

It's a bit like buying a better graphics card for a better screen resolution...you'll only notice it if the monitor can take advantage of the higher resolution otherwise it won't make much difference. If you're not hitting the limit of 32bit then you won't notice any benefit.

You'll probably see more effect in Photoshop and compositing applications as they rely much more heavily on RAM.

Amurrell
03-31-2009, 06:46 AM
I had the same problem. I knew 64bit was supposed to address more memory but it was also supposed to double the amount of info. streaming to the CPU by provinding a larger pipeline (32bit as opposed to 64bit) In rendering it didn't do squat, but as far as handling polygons, the 64bit version was much better. Here is some info...
http://en.wikipedia.org/wiki/64-bit

According to the article though...

"Also, 64-bit processors calculate particular tasks (such as factorials of large figures) twice as fast as working in 32-bit environments (given example is derived from comparison between 32-bit and 64-bit Windows Calculator; noticeable for factorial of say 100,000).[citation needed]

While 64-bit architectures indisputably make working with large data sets in applications such as digital video, scientific computing, and large databases easier, there has been considerable debate as to whether they or their 32-bit compatibility modes will be faster than comparably-priced 32-bit systems for other tasks. In x86-64 architecture (AMD64), the majority of the 32-bit operating systems and applications are able to run smoothly on the 64-bit hardware"

So in the end...I really have no idea why render calculations aren't handled better.

JonW
04-02-2009, 06:01 AM
I found LW 64 was very slightly slower than 32 (I think back at about 9.3, don’t know if its different now) but I needed the ram, around 6 to 10 gb these days for a scene, & virtual ram is just too slow, even if you are just a little bit short on ram.

Sensei
04-02-2009, 10:36 AM
64 bit code has to deal with larger amount of data due to twice larger size of f.e. memory pointers.

If you would run code on Core 1 Duo (32 bit processor), and Core 2 Duo (64 bit processor), running at the same clock speed, you would see difference (Core 2 Duo works noticeably faster).

Lightwolf
04-02-2009, 10:41 AM
If you would run code on Core 1 Duo (32 bit processor), and Core 2 Duo (64 bit processor), running at the same clock speed, you would see difference (Core 2 Duo works noticeably faster).
And unlike AMDs, Core 2 CPUs (and all derivatives) suck in 64-bit mode. The i7 seems to do better.

Cheers,
Mike

caesar
04-02-2009, 11:56 AM
And unlike AMDs, Core 2 CPUs (and all derivatives) suck in 64-bit mode. The i7 seems to do better.

Cheers,
Mike

Thatīs true. A lot of Core 2 inovattions (branch prediction, etc) do not work in 64bit...

clagman
04-09-2009, 12:37 PM
Don't forget that CPUs have had 80 bit FPU for a long time now. The only way the newer hardware will run faster is if you can write the code to take advantage of the additional 64 bit registers. Otherwise all you are really getting out of the deal is the 64 bit RAM access (which is actually very nice to have these days).