Water Render times

[buzzzzz]

Hi,

3.02 p4 with Hyper Threading using only 50% cpu.

I'd just like to point out that a P4 with Hyper Threading is not quite the same as true dual core machine, or one with multiple independent processor chips. When a P4 HT says it's using 50% it's really using much nearer 100%. An HT chip has one full processor and a "virtual" processor. In a somewhat simplified description, this virtual processor works by putting instructions into the gaps between the instructions the full processor is working on. Chips like the P4 often have gaps in their instruction queue or pipeline. The maximum theoretical performance increase you can get with HT is maybe 20%, realistically probably somewhere around 10%, compared to theoretically 100% for a chip with two full processors like a dual core one.

Windows sees the HT chip as two separate processors, even though the bulk of the processing is always being done by the full processor and the virtual processor doesn't contribute nearly so much. Due to this a machine with an HT chip will say it's using 50% CPU when really that means it's using 100% CPU. When TG2 is multithreaded you might get a 10% increase in rendering speed, maybe, whereas a true multiprocessor machine could potentially get a 100% speedup ( though it might realistically be more like 50-60% ).

I need to write a FAQ for this . I just thought I would mention this to let you know your machine is running much closer to 100% CPU use than 50%. My PC is a 3.0 GHz P4 HT machine too.

Regards,

Jo

Ok Thanks for the info jo.    Just thought I would mention that I tested running One instance of TGTP with Hyper Threading Enabled and Task Manager said that tgd.exe was using 50 % cpu as I noted earlier. So I rebooted and disabled HT and then tgd.exe was using 100% cpu as expected. I rebooted again renabled HT, started a First instance of TGTP which was back to using 50% cpu. So I thought What the Hell? I'm only using 50% so I started a Second instance of TGTP and cpu usage went up to 100% as expected right? 2 x 50% = 100% right?  Didn't run that way for long but seemed to be ok.  I main thing I  like about Hyperthreading is that I can be rendering and doing pretty much anything else I want without any noticeable lag in performance. I thought about disabling HT again and and trying to run 2 instances of TGTP but was afraid to without a Fire Extinguisher near by. 

Thanks Again jo!

 

[3DGuy]

HT only simulates 2 cores. Windows sees 2 cores of which 1 core is apparently using 100% of it's power. Using the simple math that windows uses, it 'thinks' 1 core @ 100% another core at 0% that makes 50%. But with HT it's not that simple. It's actually really close to 100% actual usage. HT doesn't mean you actually have 2 cores like the core duo 2 chips.

So in short, with HT the taskmanager is simply reporting the wrong figures.

[buzzzzz]

HT only simulates 2 cores. Windows sees 2 cores of which 1 core is apparently using 100% of it's power. Using the simple math that windows uses, it 'thinks' 1 core @ 100% another core at 0% that makes 50%. But with HT it's not that simple. It's actually really close to 100% actual usage. HT doesn't mean you actually have 2 cores like the core duo 2 chips.

So in short, with HT the taskmanager is simply reporting the wrong figures.

You just said the same thing as jo only in different words and I understand that. I also know I don't have two cores because I built my machine.

In addition I performed a render test using the same tgd with and without HT and the render times were nearly the same. So, I guess what I'm trying to convey here is that with HT enabled I can render and run other processes without any ill effects on performance or render times. Which for me is a good thing.

[Dark Fire]

As MOST of us don't have render farms, we won't be able to play the TG game anymore.....

You don't need a render farm. My software can run off a USB device so you can render wherever you go. Most workplaces have computers these days, so you could render while at work.

Right, try that at most companies and you get fired on the spot.

I have never heard of that happening. I think whether it is misuse or not depends on what you do with the resulting render. If something is found with SETI, it could potentially damage some companies, so I can understand the fact that some companies would not like it.

I could search for registry entries T2TP makes and make it into a totally portable program, thus making its previous usage of it undetectable. If you are desparate I could also make a button of key combo that would kill T2TP and any associated software.

Also, realistically, a company should not care too much about you using waste that does not pose a security threat. For example, if a company was throwing out a load of blank paper (save the trees!) it would not be called misuse of company property if you offered to take the paper and actually use it. The usage of spare processing time can be thought of in the same way - the company cannot recover yesterday's wasted processing time so, if it is not going to be used by the company, it makes sense for you to use it providing you do not pose a security threat (and using T2TP is not a security threat).

[3DGuy]

I've been part a group that did something similar to SETI@home, which used distributed processing. That process also runs in the background at the lowest priority. There were several reports (from the Anandtech crew I think it was) of sysops that got fired just because they installed that software on every server.

If you're using spare cpu time, you're actually consuming more power. A cpu that's idle uses less energy than one that's fully occupied, in that respect you're stealing money. More power=more electricity=money. Fact is, most companies don't want you installing anything on their computers. It could even be in your contract. But a decently configured workstation won't even let you install anything, that is if the sysop knows what he's doing.

If your boss lets you, by all means, use workplace computers as much as you want, but if you do it without telling anyone, you could be in serious trouble (anything from a slap on the wrist to losing your job). It doesn't matter if a program poses a secutity threat or not. You just don't install 'random' software on company computers.

[Dark Fire]

But a decently configured workstation won't even let you install anything, that is if the sysop knows what he's doing.

I've never met a good sysop.

It doesn't matter if a program poses a secutity threat or not. You just don't install 'random' software on company computers.

If I ran a company, I would allow distributed computing stuff to run on the company computers. However, I may never end up running a company...

There were several reports (from the Anandtech crew I think it was) of sysops that got fired just because they installed that software on every server.

If you're using spare cpu time, you're actually consuming more power. A cpu that's idle uses less energy than one that's fully occupied, in that respect you're stealing money. More power=more electricity=money. Fact is, most companies don't want you installing anything on their computers. It could even be in your contract. But a decently configured workstation won't even let you install anything, that is if the sysop knows what he's doing.

Firstly, I doubt anyone here would be stupid enough to start installing T2TP on every server in their workplace. Secondly,you are not always using more power when using the CPU more. Some CPUs (and maybe all, but I'm not an expert on CPU technology) power up different parts of themselves in steps. However, to exploit just the spare powered parts of the processor would require a truly amazing program.

...(anything from a slap on the wrist to losing your job).

It's amazing how closely related those two things are...

[3DGuy]

All processors use more power when used more. Why do you think a processor gets hotter when using 100% usage? That's because more power is required which in turn produces more heat. It's not different parts of the proc that get activated. What you're referring to is speedstepping which is used in laptops for instance. When it's idling or on battery power it switches to a lower frequency... to save power. According to your assumtions it wouldn't matter if you ran a background render on a laptop or not and still get the same batterylife out if it, that's simply not true. If that doesn't show you more power/energy is required than I don't know what will.

[Dark Fire]

All processors use more power when used more. Why do you think a processor gets hotter when using 100% usage? That's because more power is required which in turn produces more heat.

My CPU gets hotter the longer I leave my computer on - it is not affected much by rendering. Maybe I just have good cooling.

According to your assumtions it wouldn't matter if you ran a background render on a laptop or not and still get the same batterylife out if it, that's simply not true. If that doesn't show you more power/energy is required than I don't know what will.

According to my assumptions if you were using a program that, for example, used the CPU at 99%, if I ran Terragen with a low priority so that it used up that final 1% the battery life would be unaffected. Obviously running a render would have a huge effect on tha battery life compared to a laptop running nothing and, besides, I rarely get any battery life out of a laptop, so I can't test that. I was probably talking about a rare CPU type that I read about in PCPlus...

[3DGuy]

It gets hotter because your case warms up. In other words, you need some airflow in there. Measure the temp when windows is idling, then let tg run a render and check the temp after 5 mins, you'll see an increase of a few degrees.

Anyhow, this has less and less to do with the title of the thread ;p

[Dark Fire]

...you need some airflow in there.

I have plenty of that (there are very few parts of the case without holes). I feel I didn't explain myself properly last time - my CPU gets hotter the longer I leave my computer on until it reaches about 40^oC. After that it stays at about the same temperature no matter what I do. The same thing happens with my GPU as well. As I said, maybe I just have good cooling.

[3DGuy]

Sorry, but I just don't buy that. Unless you have a kick ass watercooling system, there's no way that your cpu doesn't get hotter under full load, that's simply impossible with air cooled systems, no matter how advanced it is.

Unless you have some background program running already using 100% that is.

[Dark Fire]

I think it's got something to do with the fact that I am running an old processor with a much newer case and fans.

[Dark Fire]

Somehow we have progressed from water render times to water cooling...

[3DGuy]

Having an older processor has nothing to do with it. You're either reading it wrong or using the wrong software. I've seen and done enough tests and measurements to know there's no processor that doesn't get hotter under full load vs. idle.

[buzzzzz]

Hot Water Springs! Great Idea for a Render! Thanks you two!