render time drastically different #96019

New Issue

HF · 2022-02-24T23:16:59+01:00

HF commented

2022-02-24 23:16:59 +01:00

System Information
Operating system: Windows-10-10.0.19042-SP0 64 Bits
Graphics card: NVIDIA GeForce RTX 2080 SUPER + 2070super

Broken: version: 3.1.0 Beta, branch: master, commit date: 2022-02-23 19:16, hash: 88712453f6

Short description of error
in this file the render time changed for the exact same scene, ranging from 8sec to 12 sec on average. one time it even went up to 20 sec

Exact steps for others to reproduce the error
1.blend
this is the file. hit render many times and see the render time change

**System Information** Operating system: Windows-10-10.0.19042-SP0 64 Bits Graphics card: NVIDIA GeForce RTX 2080 SUPER + 2070super Broken: version: 3.1.0 Beta, branch: master, commit date: 2022-02-23 19:16, hash: `88712453f6` **Short description of error** in this file the render time changed for the exact same scene, ranging from 8sec to 12 sec on average. one time it even went up to 20 sec **Exact steps for others to reproduce the error** [1.blend](https://archive.blender.org/developer/F12886041/1.blend) this is the file. hit render many times and see the render time change

HF commented

2022-02-24 23:16:59 +01:00

Added subscriber: @Hongyu

Alaska commented

2022-02-24 23:26:19 +01:00

Added subscriber: @Alaska

Alaska commented

2022-02-24 23:26:19 +01:00

Changed status from 'Needs Triage' to: 'Needs User Info'

Alaska commented

2022-02-24 23:26:19 +01:00

Render times are really consistent for me on the system listed below. (Render times were between 9.3 and 9.5 seconds)

I can think few potential reasons for why you're seeing inconsistent render times.

The file you uploaded doesn't include any textures. As such I might be observing a different result as the issue could be related to the textures that aren't there for me.
In your report you say you have two GPUs. Do you have both GPUs enabled during rendering? Do you have a GPU and a CPU enabled? Two GPUs and a CPU? If you have more than one device enabled for rendering, then that could lead to the performance loss as work scheduling across multiple devices is less than ideal and can lead to render time variance or overall performance loss.
The hardware you're using for rendering is overheating (unlikely)

System Information
Operating system: Linux-5.16.0-1-amd64-x86_64-with-glibc2.33 64 Bits
Graphics card: NVIDIA GeForce RTX 3060/PCIe/SSE2 NVIDIA Corporation 4.5.0 NVIDIA 510.54
Blender version: 3.2.0 Alpha, branch: master, commit date: 2022-02-23 03:15, hash: 06bc20f61a
Render mode: GPU Compute with OptiX using ONLY the RTX 3060.

Render times are really consistent for me on the system listed below. (Render times were between 9.3 and 9.5 seconds) I can think few potential reasons for why you're seeing inconsistent render times. 1. The file you uploaded doesn't include any textures. As such I might be observing a different result as the issue could be related to the textures that aren't there for me. 2. In your report you say you have two GPUs. Do you have both GPUs enabled during rendering? Do you have a GPU and a CPU enabled? Two GPUs and a CPU? If you have more than one device enabled for rendering, then that could lead to the performance loss as work scheduling across multiple devices is less than ideal and can lead to render time variance or overall performance loss. 3. The hardware you're using for rendering is overheating (unlikely) **System Information** Operating system: Linux-5.16.0-1-amd64-x86_64-with-glibc2.33 64 Bits Graphics card: NVIDIA GeForce RTX 3060/PCIe/SSE2 NVIDIA Corporation 4.5.0 NVIDIA 510.54 Blender version: 3.2.0 Alpha, branch: master, commit date: 2022-02-23 03:15, hash: `06bc20f61a` Render mode: GPU Compute with OptiX using ONLY the RTX 3060.

HF commented

2022-03-07 00:01:11 +01:00

i only have 2 GPU enabled

Alaska commented

2022-03-07 01:13:54 +01:00

In #96019#1317737, @Hongyu wrote:
i only have 2 GPU enabled

Rendering with two devices (such as two GPUs) can lead to performance variations in re-renders as the work scheduling across multiple devices, specifically if they have different performance characteristics, is less than ideal and can change quite a bit from run to run. This is possibly the issue you're experiencing.

> In #96019#1317737, @Hongyu wrote: > i only have 2 GPU enabled Rendering with two devices (such as two GPUs) can lead to performance variations in re-renders as the work scheduling across multiple devices, specifically if they have different performance characteristics, is less than ideal and can change quite a bit from run to run. This is possibly the issue you're experiencing.

HF commented

2022-03-07 20:32:50 +01:00

In #96019#1317759, @Alaska wrote:

In #96019#1317737, @Hongyu wrote:
i only have 2 GPU enabled

Rendering with two devices (such as two GPUs) can lead to performance variations in re-renders as the work scheduling across multiple devices, specifically if they have different performance characteristics, is less than ideal and can change quite a bit from run to run. This is possibly the issue you're experiencing.

Can this be fixed or every renderer has this issue and there is no way to fix it

> In #96019#1317759, @Alaska wrote: >> In #96019#1317737, @Hongyu wrote: >> i only have 2 GPU enabled > > Rendering with two devices (such as two GPUs) can lead to performance variations in re-renders as the work scheduling across multiple devices, specifically if they have different performance characteristics, is less than ideal and can change quite a bit from run to run. This is possibly the issue you're experiencing. Can this be fixed or every renderer has this issue and there is no way to fix it

Alaska commented

2022-03-08 08:50:14 +01:00

Every renderer (that I can think of) has these issues, just to different degrees. There are plans to improve work scheduling in Cycles across multiple devices in the future and a side effect of it might be that the consistency of re-renders is greatly improved.

Alaska commented

2022-03-08 08:57:29 +01:00

Although, this could also be a different issue that you're experiencing. And I can't reproduce it due to me only having 1 GPU.

Pratik Borhade commented

2022-08-18 07:54:16 +02:00

Added subscriber: @PratikPB2123

Pratik Borhade commented

2022-08-18 07:54:16 +02:00

In #96019#1318526, @Alaska wrote:
Every renderer (that I can think of) has these issues, just to different degrees. There are plans to improve work scheduling in Cycles across multiple devices in the future and a side effect of it might be that the consistency of re-renders is greatly improved.

@Alaska hi, can we close this report if slow rendering with multi-GPU is a known issue?: #89833 (Cycles: multi-device rendering performance)

> In #96019#1318526, @Alaska wrote: > Every renderer (that I can think of) has these issues, just to different degrees. There are plans to improve work scheduling in Cycles across multiple devices in the future and a side effect of it might be that the consistency of re-renders is greatly improved. @Alaska hi, can we close this report if slow rendering with multi-GPU is a known issue?: #89833 (Cycles: multi-device rendering performance)

Alaska commented

2022-08-18 11:02:55 +02:00

@PratikPB2123 We can probably close this report as the issue the user reported is probably the mutli-device rendering issue.

Pratik Borhade commented

2022-08-18 12:15:04 +02:00

Changed status from 'Needs User Info' to: 'Archived'

Pratik Borhade closed this issue

2022-08-18 12:15:04 +02:00

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render time drastically different #96019