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TIP: MBPr + eGPU performance with lid open

PostPosted: Sat Feb 16, 2019 5:54 pm
by joe12south
Sharing my findings in case this is helpful to someone else, or someone can point out how to eek out even more performance.

SYSTEM
Mac: 2017 15" MBPr (2.9 Ghz 16GB)
eGPU: Radeon Vega Frontier Edition (16GB)
Project/Cache: Internal SSD (1,600/1,800 r/w)
Source/Optimized: External USB SSD (870/980 r/w)
Nearline: Drobo 5Dt (231/267 r/w)
Backup: Drobo 3

tldr: If you want to run a dual-monitor set-up including the MBP built-in screen, manually set these GPU options: Turn OFF "Use optimized image transfer for viewers"; Choose Open CL for "GPU processing mode"; Choose Manual "GPU selection method" and check both internal and external GPUs.

Long version:
While I could get good timeline performance if I closed my MBP's lid and drove a 4K display through the eGPU almost no matter what the settings, frame rate roughly halved and playback became completely erratic if the MBP was open.

I was resigned to work on a single monitor when I happened to notice that render times were actual FASTER when the lid was open. Using at the Activity Monitor, I verified that this was likely because both GPU's were being utilized. (When lid closed, they were not.)

This set me to trying various combinations of settings to get acceptable timeline performance with the lid open.

Ultimately, with the settings above, I get performance similar to if the lid is closed. Timeline plays smoothly and rendering utilize both GPU's. No other GPU settings yielded usable results with the lid open.

PS. While doing this, I noticed this counterintuitive situation: If using an external monitor with no eGPU, cached timeline (all blue bar) played back as expected, but if using an external monitor with eGPU, cached timeline played back as bad as if not cached.