Dualprocessor usage when rendering

Winston wrote on 4/12/2002, 4:01 AM
Hello,
My machine: ASUS DualAthlon with 2x1800, 1GB DDR, 2k Pro, all works perfectly, but some strange behavior of both processors when rendering.
I render a series of stills with the GREAT SF filmeffects.
While I understand, that the usage of both prozessors may change with the complexity
of the effects (should not, but maybe the obviously brilliant SFprogrammers will have something to work in the future), the WindowsTaskManager shows, that most time
1 processor is idle, but sometimes, really coincidental to me, both processor run 100% and the frames fly.
This happens independend from memory status (full or empty), and it happens -strange to me- NOT when effects change, but while rendering a still with the same parameters
over time.
When rendering, I have no other application running, but maybe some windowsworkers run.
Any comment or idea to improve hardware-settings?
Regards1

Comments

Control_Z wrote on 4/12/2002, 1:27 PM
You're lucky. When I had dual procs I could never get VV3 to use much of either. i.e., there were times when I wasn't using the machine I wish I could have cranked em both up to 100%.
bakerbud9 wrote on 4/12/2002, 1:36 PM

Hi Winston,

I can't answer your dual CPU usage question, but perhaps you can answer a question of mine. I am thinking of upgrading to a dual Athalon MP system. How close to true real-time does your Athalon 1800 processors get you? In particular, I'm wondering how long it takes to render cross dissolves, color corrections, and rolling credits/text overlays.

Sincerely,

Nate
nlamartina wrote on 4/12/2002, 2:08 PM
Winston,

This is only a guess, but I believe the way Vegas renders video with dual processors is by trading off source frame after source frame, ie, Proc. A does frame 1, Proc. B does frame 2, A does 3, B does 4, etc. So if you were rendering a still over 5 minutes, then whatever processor that frame landed on would be left on its own for the duration of that "frame", however long it took.

Just a guess remember. I'm sure someone else will drop in later and be able to tell you for sure.

Hope this helps,
Nick LaMartina
Jdodge wrote on 4/12/2002, 2:53 PM
Hi Everyone,

These are the two cents I can add:

Vegas uses many 'threads' while playing. Each thread is qualified to be processed on any available CPU. The system handles all that for us. Anytime you have more than 1 thread and a multi-CPU computer, more than likely both CPUs are going. So, the system splits tasks between the two processors, even in an audio-only project.

Dual processors also pay off when rendering DV. If we detect two or more processors, we compress to DV on one thread and render/compose video frames on another so you essentially get "free" DV compression. This is new to Vegas Video 3.0.

Hope this helps clarify things for you. Perhaps someone else from here would further clarify this for our users?
bakerbud9 wrote on 4/12/2002, 4:09 PM
Hi J,

Hey, have you had any experience using Vegas on a Dual 2 GHz machine? I am wondering how close to true real-time the performance is on such a system. For example, if I understand your post correctly, you're saying one CPU will work on a cross-dissolve while another CPU will work on compressing the frame into the DV format. Is that correct? If so, I'm wondering how Vegas performs on a Dual 2 GHz machine. I am thinking of upgrading my system, but I don't want to do that now if I still wont get true real-time performance for simple effects (I'd rather wait another year or so until the CPU speeds are fast enough).

Sincerely,

Nate
Winston wrote on 4/13/2002, 7:09 AM
Hello,
first I would like to repeat more precisely what I watch. I hope my germanenglish doesn't prevent this.
When rendering a clip (i.e. film effect with constant parameters, no keyframes) the processors are most time used: Proc A approx. 90%, Proc B approx. 25%, in sum approx. 50-65 %.
While rendering, Proc B goes suddenly (for me) unsystematically also to 90% and after a few seconds down again to 20%. At the condition 90+90 I see the framecounter flying.
My question was now: can the Windows-Background influence the processor-sharing and what, i.e., to shut off / change in Windows-settings. Or is this behaviour a SF matter.
To the topic "Realtime":
It has been treated in many fora, of course it must be seen relative to the price category of the product.
To judge a NLE System, to me is ONLY important "what comes out behind" as our earlier chancellor Kohl always stated. Realtime means to me, I can do all editing without any waiting and with a good preview at any time. Final rendering time is not so important to me.
I must repeat, what many VV3 user stated here, and in many other puplications: VV3 is unique in the sum of its possibilities and -also important to me- the elegance as these possibilities are brought to the user. Because I worked with "Pro"-Systems before and now in parallel, I know what I am talking about. One can not measure this packets qualities in terms like realtime, yuo see this qualities only by use.
Projects (noncommercial) which slept on my "Pro"-system since long time, because the realization was too time/nerve consumpting, I have imported in VV3 and completed with much fun.
Finally, the topic "processor-tasksharing" is therefore only a sporting side-topic for me.

Measurable facts: I render a 3 sec. crossfade to new track in 8 sec. (bestquality, PAL)
Proc. A works around 85%, Proc.B around 35%, sum around 60% (of 2x1800 Mhz).
Maybe the same speed as a 2gig pentium.
So, why buy a DualAthlon? When I encode to mpeg2 with TMPEG, both processors run 100% and one can forget the rest of the world.
Regards!
kosstheory wrote on 5/25/2002, 1:04 PM
I have gotten excellent results with the following system:

Dual AMD Athlon MP 2000+ processors
ASUS A7M266-D Motherboard
1 GB PC2100 DDR RAM ECC

When Rendering From DV to DV I achieved 100% CPU usage on both CPUs for the duration of the render, which was quite fast! I was in awe! Seeing those frames shoot by on the preview was a sight for sore eyes. I've never seen anything quite so beautiful.

A lot of people say that the AMD Athlon MP processors are not stable enough to compete with the P4s. This baby is rock steady! I can throw anything at it, and it just gobles it up, and keeps on trucking. And I saved hundreds!

One thing that I am a little concerned about is the CPU usage during other types of renders. Like the mpg2 file I'm rendering right now. The CPUs are only being used to 50%. I suppose that the main concept mpeg2 encoder has no optimization for dual cpus? Looking at the performance tab of the task manager, it looks like CPU 1 is at about 80% and 2 seems to vary between 20% and 30%. There was an earlier post that stated that dual processor support for activities other than DV encoding might use one processor for decoding, and one for encoding. I suppose what the performance tab is showing might be proving that this scenario is true.

I hope that future releases of the main concept mpeg2 codec included with vegas will utilize the dual cpu configuration more efficiently. It is a puzzle why 100% of atleast one of the CPUs isn't being employed. As it is 80+20=100. So, I would probably get about the same results with a single CPU when doing anything other than DV encoding. Oh well. Maybe they should advertise it as "Limited" Dual CPU support, until it's further optomized?

Just my 2 cents