Lightroom Classic 10 M1 Macs with Rosetta: excessive disk read/writes to SSD

Community Beginner ,
Dec 16, 2020 Dec 16, 2020

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Usually, I'd consider this kind of digging into stats when all works well as a bit dumb but actually... this is truly a bit worrisome.

 

I have MBP13 with M1 Apple Sillicon processor. 16 GB RAM / 1TB SSD. Lightroom Classic runs blazingly fast! But there's a very concerning issue. 

M1 MBP has quite intense swappiness (indicated by kernel_task writes) but running Lightroom Classic results with absolutely CRAZY DISK WRITES by kernel_task.


- Today in the morning I've been mostly running Slack + Safari today and then opened Lightroom Classic twice just for testing and I've had 450GB of writes!


- To make a bit more "scientific" test I've restarted the machine and and launched no application except the Lightroom Classic. Almost instantly it took13-14GB of memory (I'd not care honestly) but inspecting the process showed that Virtual Memory grows steadily as you operate in "Develop" tab. What's most important this is reflected in writes to disk done by "kernel_task". In 15 minutes of scrolling through images and applying some presets at Random and I'm at whopping 20GB written to disk by kernel_task. And this is not some weird "cache writes" that do not affect the SSD like some people on Mac forums tries to "explain",  SSD health tools confirm those writes.
- It doesn't happen when scrolling images in "Library" and basically doesn't persist when I do nothing or close Lightroom Classic and work with other applications. 

I have no idea what's the reason but discussions on Mac forums indicate that it's widespread.

It seems like some Lightroom/Rosetta/Swapping bug. Feels almost like using Lightroom Classic @rosetta makes kernel constantly drop GPU's memory content on disk (which would explain why some people report that disabling GPU acceleration helps a bit.).


Swapping is all fine on modern machines but writing hundreds of gigabytes of data in a few hour session in Lightroom Classic is definitely not. Even the best SSDs (I mean, assuming real-world durability being as high as 1petabyte write lifetime) cannot survive this in the long run!

 

 

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Community Beginner ,
Dec 16, 2020 Dec 16, 2020

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AN UPDATE AFTER SOME INVESTIGATION:

 

Resetting preferences, rebuilding catalogue and all those tweaks did not help. 

 

What helps is playing with GPU acceleration settings.

For me, with the following setup:

 

- MBP M1 16GB RAM / 1TB

- No external display (I don't have access to mine at the moment and I'm afraid it's going to make an impact...)

 

The situation is following with different GPU acceleration settings:

 

- Full acceleration on:

  - Lightroom reserves around 23-25GB Virtual Memory at least;

  - ABSOLUTELY CRAZY SWAP WRITES

   ... and awesome performance.

- Basic acceleration:

   - Lightroom reserved around 16GB Virtual Memory;

   - OK behaviour, kernel_task is not writing to swap like crazy.

    ... performance still fine (as in very decent upgrade from 2016MBP13)

- No acceleration:

   - Lightroom reserved around 12GB Virtual Memory;

   - OK behaviour, kernel_task is not writing to swap like crazy.

    ... performance oh well, if that I'd have to live with, I'd be pissed because this is not what I've expected from this machine.

 

 

All in all, I think the reason for this madness with full GPU acceleration on is here:

Untitled (1).jpg

When full acceleration is on Lightroom claims 10.5GB out of 16GB of unified RAM and writes some that to it like crazy. That results in crazy swapping. It's actually amazing how good it functions on M1 mac, no slowdowns but it's still really dangerous with regular usage... Even best SSDs will die in 2 years with that heavy writes. 

 

For now, I can live with basic acceleration and keep fingers crossed that it'll still solve the problem for me even with 4k display connected...

 

But it looks like something that Adobe SHOULD SOLVE.

At the very least there should be an option to set memory value to let's say, 2-4GB.

It would still probably give us some performance improvement without crazy disk writes, at least on 16GB models. 

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Community Beginner ,
Dec 17, 2020 Dec 17, 2020

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Support this.
I'v been writing around 1tb/day with kernel_task (swap) because of how LR is dealing with VRAM/RAM and swap.

Adobe must look into it quickly!

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Adobe Community Professional ,
Dec 17, 2020 Dec 17, 2020

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See the article at the link below with respect to LrC support for M1 Macs and Rosetta.

https://www.lightroomqueen.com/lightroom-macos-bigsur-compatibility/ 

 

 

Regards, Denis: iMac mid-2015, 5K 27”, GPU 2GB, Ram 24GB, HDD 3TB, macOS 11.2.3, LrC 10.2, Lr 4.1, Ps 22.3, Pr 14.8.0; Camera OM-D E-M1.

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Community Beginner ,
Dec 17, 2020 Dec 17, 2020

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1. First of all: https://helpx.adobe.com/lightroom-classic/kb/macos-big-sur-compatibility.html

  Adobe claims there are no issues and it's simply not true.

 

2. The same behaviour of GPU acceleration causing extreme writes to disk is happening with Adobe Lightroom CC that has been already released with full native support for M1s. 

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