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virtualcomposer
05-04-2011, 12:22 AM
Does LW 9.6 utilize hyperthreading? Is there much of a difference in speed if using it vs not using it? I do allot of radiosity so does that make a difference?

lino.grandi
05-04-2011, 02:06 AM
Does LW 9.6 utilize hyperthreading? Is there much of a difference in speed if using it vs not using it? I do allot of radiosity so does that make a difference?

It makes a huge difference. Radiosity and render in genetal take full advantage of hyperthreading in LightWave.

JonW
05-04-2011, 02:14 AM
I tested my W5580 when I first got the box almost 2 years ago using the 3dspeed scene, with HT on & off. From memory with HT on the render was something like 30% or more quicker. I did write down the break up of radiosity & render times, but now I doubt I would find or even still have the notes.

In general I would keep HT on. But if all the cores are only working at a very low percentage (Mac issue in some situations) it would be worth doing a few quick tests with HT off & see it the box is actually any quicker.

But with 9.6 on a PC, HT on is the way to go.

virtualcomposer
05-04-2011, 09:32 AM
well that's nice to know. I'll do some test over the next few days. I'm a huge fan of radiosity so what ever makes that render quicker is all good for me. :D

virtualcomposer
05-04-2011, 05:31 PM
how do you set up hyperthreading in Lightwave? I also have 12GB of RAM so I would want to utilize all of that for renders if possible.

JonW
05-04-2011, 05:41 PM
You don't.

On a PC it's in BIOS, usually holding down the delete key on start up. On a Mac I don't know.

Jarno
05-04-2011, 05:54 PM
Software has no control over hyperthreading. It is something that the hardware handles. To the software a hyperthreaded CPU core just looks like two CPU cores. So it is not something you turn on or off in LightWave.

---JvdL---

virtualcomposer
05-04-2011, 05:54 PM
You don't.

On a PC it's in BIOS, usually holding down the delete key on start up. On a Mac I don't know.

oh so it's automatic then?

virtualcomposer
05-04-2011, 05:54 PM
Software has no control over hyperthreading. It is something that the hardware handles. To the software a hyperthreaded CPU core just looks like two CPU cores. So it is not something you turn on or off in LightWave.

---JvdL---

So my Mac Pro will automatically know when I start rendering?

JonW
05-04-2011, 06:59 PM
Software has no control over hyperthreading. It is something that the hardware handles. To the software a hyperthreaded CPU core just looks like two CPU cores. So it is not something you turn on or off in LightWave.

---JvdL---

Take 1 of my W5580 CPUs as an example. It has 4 Cores. It can also have HT which when turned on (& this is done in Bios on a PC before the PC is actually running & the OS is running) give the CPU 4 additional Virtual Cores. So now there is a total on 8 Cores (or threads for the purposes of LW rendering).

These 4 additional cores don't double the speed of the CPU. In some applications there maybe little or even negative benefit from the additional 4 cores. But in general on a PC it's worthwhile turning HT on, & typically you get about 30% better performance when rendering with LW. But you will get less performance on single core work in Modeler & Layout. But in most cases we are prepared to give up this speed on a single core as it's more critical to have the CPU working at 100% when rendering.

The W5580 can render at 100% with 4 cores, & also run at 100% with 8 cores (4 real cores & 4 virtual cores). Rendering with 8 cores each core is rendering a bit slower but you have 8 cores instead of 4, so overall more work is being done (in other words LW rendering is roughly 30% quicker).

Reading our Mac forums there appears to be some CPU efficiency issues in some situations, whether it's HT or the nature of the CPU or the OS or LW, it's not clear. Hopefully people with x55xx/x56xx CPUs can shed some more light & help towards a solution.

In the meantime one will need to be aware of the issue & use work arounds if you want your CPUs running at 100% for the bulk of the render.

Turning off HT may or may not help with a Mac. How to turn HT off, there is probably some info at Mac Rumours etc.

While working also keep the CPU Activity Monitor on until you have worked it out.

But regardless of all the above issues a well optimised scene will more than likely give you a quicker render than CPU/HT/OS/LW issues, but it's disappointing when CPUs don't run at 100%.

I would not get too stressed out about it, use the best tools you have at hand. Any old Macs lying around, flog these old boxes to within an inch of their life with Screamernet! There is too much money in these old boxes to let them have a slack day lazing around in retirement!