The launch of the new iPad Pro with M1 chip has once again sparked conversation about how the iPad hardware is vastly outpacing the operating system and software ecosystem that it can run. Many people are setting their hopes on iPadOS 15 at WWDC to announce overhauls to multitasking, external display support and file management to bring iPad productivity closer to what is possible with macOS.
However, there’s an even more direct limitation of iPadOS today for customers hoping to use that high-specced M1 chip for pro apps. It turns out that the operating system on the new iPad Pro limits all third-party apps to a maximum of ~5 GB RAM each.
This OS policy limit has come to light in part because of an overnight update to digital art app Procreate, which is now officially optimized for the new iPad Pro.
Procreate enforces layer count limits to accommodate the constrained memory environment of an iPad and updates those limits with each hardware generation, as Apple adds more RAM to its tablets.
With the latest update installed, customers are seeing layer counts on a default canvas increase from 91 with the 2020 iPad Pro to 115 on the M1 iPad Pro models.
Historically, Apple has never discussed how much RAM a particular iOS device has. However, the company publicly reports memory specs for the 2021 iPad Pro with M1 chip: the iPad features 8 GB RAM as standard, doubled to 16 GB RAM on the 1 TB and 2 TB models.
However, Procreate users have been somewhat disappointed to find that the 115 layer count is the same across base model iPad Pros and those higher-specced models with double the RAM.
As Procreate notes in a tweet, it turns out the that the iPad’s operating system only allows an app to use a maximum of ~5 GB of RAM on either the 8 GB RAM or 16 GB RAM iPad Pro. If an app uses more than that, it is immediately force-quit and evicted from memory by the system’s jetsam process.
This means a single pro app is unable to use all of the M1 chip’s resources. The additional RAM found in the 1 TB and 2 TB models will mean that more apps at a time can stay alive in memory for multitasking purposes, but an individual application will behave the same as if it was running on the base model iPad Pro.
Per-app RAM limits have existed in iOS since the beginning, but the limitation is more pronounced with this latest generation of iPads simply because the absolute numbers are bigger. For instance, the 2018/2020 iPad Pro with 6 GB RAM would enforce a per-app RAM limit of 3 GB, or about half of onboard physical memory.
But on the new iPad Pro, the 5 GB limit represents under a third of overall system memory for the top-spec iPads with 16 GB RAM, leaving almost 11 gigabytes under-utilized from the perspective of a single professional application (calculated proportions exclude minimum RAM requirements for the actual system).
This gotcha affects pro multimedia apps the most, like image and video editors, which can always benefit from having additional memory available. Procreate has already said that if Apple increases the limits, it will update to give iPad Pro customers as many layers as possible.
We’ll have to wait to see if this situation changes with iPadOS 15, which Apple will officially announce in a little under two weeks’ time.