Author Topic: Varied Render Speeds  (Read 8238 times)

2016-11-07, 03:59:24

TomEnokR

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I own a dual-core i7 surface book. While rendering a 120 frame scene, I set my noise parameter to 10% and did several test-renders. I found that each frame came in under 1 hour. The scene has no moving objects, just a very slow rolling camera (just for movement effect). So from that, I determined that the entire render would take approximately 120 hours.

Because it's so processor intensive, I would refrain from using the computer for other things, to try to maintain render times around the hour mark. That number has been pretty consistent, even though I've had to start and stop my rendering as I moved my computer or needed to use it for other things.

However, something strange happened last night. I started the renderer, like I always do, and the renderer just started pumping out each frame with blazing speed. It was rendering every frame, at the same exact settings, at 20 minutes per frame. In other words, it was rendering 3x faster than any other time. I watched this go on for about 8 hours and had to stop the render to take my Surface Book to work.

it is now back to the 1 hour render frame, and nothing I do will give me those screaming render speeds again.  I have looked at the faster render frames and they are the exact same as the frames that took 3x longer.

Can anyone account for this phenomenon? Is there some setting in Corona that tells it to optimize both cores, or optimize memory, or that would in any way account for this anomaly?

I'd love any suggestions, because I'd do anything to get those render speeds back.

2016-11-07, 09:40:38
Reply #1

grafichissimo

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It is something I have notice too.
But i thought it was because I was using the machine for other work at the same time, anyway the render time seams generally inconsistent.
Davide Chicco - www.metrovisual.co.uk

2016-11-07, 13:04:20
Reply #2

maru

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Some possible causes of this, off the top of my head:
-running out of ram can slow down rendering drastically (so maybe you had some ram problems, and then ram usage got lower for some reason, and then higher again) - but you should see a warning from Corona in this case
-CPU lowering its performance because of high temperatures (I don't think it applies to i7s however...)
-system going into power saving mode - e.g. in case you unplugged the power adapter
Marcin Miodek | chaos-corona.com
3D Support Team Lead - Corona | contact us

2016-11-07, 16:25:13
Reply #3

TomEnokR

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First, thanks for the reply.

Each time I start a render, I restart the surface book, I clear all the cache, I turn off all non-essential startup applications, and I even disconnect from the Internet (as I don't want any CPU being utilized for system updates etc.).

So.. I know it's not a Ram issue.

I literally did EVERYTHING the same way I always do.

I'm using the current version: Corona 1.5 hotfix.

I have attached a document showing the different render times (based on when each files was saved after it was rendered by the system).  I have also attached an image of both the 60 minute and 20 minute render times. Aside from SLIGHT camera adjustment, there is NO difference.

2016-11-07, 17:51:00
Reply #4

Frood

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I set my noise parameter to 10% and did several test-renders. I found that each frame came in under 1 hour.

You had only noise level as stop condition? Can you please show the actual number of passes for frame 90 and 105? If you have no render stamp element configured you may still find it in the logs. Even if cam movement is very subtile it´s possible (and likely) that your reach those 10% noise at different pass numbers, thus at different render times.

Good Luck


Never underestimate the power of a well placed level one spell.

2016-11-07, 20:16:02
Reply #5

TomEnokR

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You had only noise level as stop condition? Can you please show the actual number of passes for frame 90 and 105?

Yes... I verified that the frames, before and after finished at 20 passes.

If you have no render stamp element configured you may still find it in the logs. Even if cam movement is very subtile it´s possible (and likely) that your reach those 10% noise at different pass numbers, thus at different render times.

This scenario wouldn't account for the fact that the frame EXACTLY before this restart was 60 minutes, and the frame EXACTLY after I stopped the render started back up again at 50 minutes plus. Further, I performed another test render on the shorter frame times, and it rendered at 60 minutes. Interestingly, however, the frames are IDENTICAL. So the frame rendered, same passes, same elements; just 3x faster.

This render time was SPECIFICALLY attributable to ONE of 9 start/stop render sessions between October 27 and today. EVERY other session was consistent. THis one was not.

I think if we could isolate the event that TRIPLED my render time, possibly everyone could benefit from this. I simply know that from my end, nothing changed.

To further add to the head-scratching, I save my project file after each render session, so had I inadvertently changed something in this session, It would have manifested itself in the next render session as well.

Something happened here that SIGNIFICANTLY increased my render times with the SAME renders.



Good Luck



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2016-11-08, 06:32:10
Reply #6

sprayer

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check temperature while rendering, MSI Afterburner with writing logs

2016-11-16, 13:22:02
Reply #7

maru

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Any new findings here? Unfortunately we have no idea what might be wrong... I do not know of any support cases like this either.
Marcin Miodek | chaos-corona.com
3D Support Team Lead - Corona | contact us

2016-11-28, 01:38:09
Reply #8

TomEnokR

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Yes.. I've finally resolved the issue!

I'm sure this issue won't apply to all, but for some, it may be helpful.

I'm rendering on a i-7 Microsoft Surface Book Laptop. I render while I travel, as well as when I'm at home. The problem that I was having is that at seemingly random times, my render speeds would vary greatly. A frame that took 2.5 hours would suddenly (magically) only take 1.5 hours the next day.

So here's the solution:  When I was rendering on an external monitor (with laptop monitor switched off), my render speeds were almost twice as fast as when I was rendering on my laptop monitor.

I think there are two reasons for this: 1. My laptop CPU ran a little hotter when using my laptop monitor, and I know that heat affects performance. But the REAL difference was in CPU utilization. 3D Studio Max was utilizing 100% of the CPU when I was using the external monitor, compared to only 80% utilization when using the laptop monitor.

So a combination of CPU temperature (as suggested by a previous post), as well as CPU utilization (less when using the laptop monitor) negatively affected my render speeds.

So the takeaway is that when you're using a laptop, utilize an EXTERNAL monitor and TURN OFF YOUR LAPTOP MONITOR. It will significantly increase render speeds.

Thanks for everyone's input and suggestions.

2016-11-28, 09:45:47
Reply #9

Christa Noel

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... But the REAL difference was in CPU utilization. 3D Studio Max was utilizing 100% of the CPU when I was using the external monitor, compared to only 80% utilization when using the laptop monitor.
a bit weird but seriously I never heard that kind of fact. have you tried to test the case with another laptop?
btw, thanx for sharing your solution. :)

2016-11-29, 00:19:22
Reply #10

Fluss

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Yes.. I've finally resolved the issue!

I'm sure this issue won't apply to all, but for some, it may be helpful.

I'm rendering on a i-7 Microsoft Surface Book Laptop. I render while I travel, as well as when I'm at home. The problem that I was having is that at seemingly random times, my render speeds would vary greatly. A frame that took 2.5 hours would suddenly (magically) only take 1.5 hours the next day.

So here's the solution:  When I was rendering on an external monitor (with laptop monitor switched off), my render speeds were almost twice as fast as when I was rendering on my laptop monitor.

I think there are two reasons for this: 1. My laptop CPU ran a little hotter when using my laptop monitor, and I know that heat affects performance. But the REAL difference was in CPU utilization. 3D Studio Max was utilizing 100% of the CPU when I was using the external monitor, compared to only 80% utilization when using the laptop monitor.

So a combination of CPU temperature (as suggested by a previous post), as well as CPU utilization (less when using the laptop monitor) negatively affected my render speeds.

So the takeaway is that when you're using a laptop, utilize an EXTERNAL monitor and TURN OFF YOUR LAPTOP MONITOR. It will significantly increase render speeds.

Thanks for everyone's input and suggestions.

Are you sure it's not a power managment issue ?

2016-11-30, 00:11:41
Reply #11

TomEnokR

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Ive checked that as well. I'll post the evidence I gathered when I have time to do a re-render and show it.

2016-12-01, 15:42:42
Reply #12

maru

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What is the resolution of your laptop monitor vs the external monitor resolution?
Do you have an integrated GPU only, or also a dedicated one?
Marcin Miodek | chaos-corona.com
3D Support Team Lead - Corona | contact us