Memory Insights is great for identifying tagged memory allocations. The LLM_Untracked though is a bit of an enigma. Is there a way to at least identify what modules, or files the allocations are coming from?
In our game, during map load, I’m seeing a peak of about 9.6GiB in just the LLM_Untracked graph, for LLM_Total at the same time we have about 14.2GiB. Whenever I set time A to the peak and run a query on the data, the LLM_Untracked memory is conspicuously missing. The size for All, in the query results, states it’s only 6.4GiB. Regardless of the grouping I use, the LL_Untracked group does not appear in the data. Is there a way to get the query to show a grouping for the Untracked memory?
Randomly instrumenting locations to identify the LLM_Untracked memory isn’t very efficient, and being able to at least narrow down where to instrument would be immensely helpful. Is this possible?
Even in a relatively fresh project (for which most new memory would just be uobjects) I get 1.1GB of LLM Untracked memory, which to me seems very high and I would like to start optimizing it immediately. Considering how little I have in my project though I wouldn’t even know where to start throwing down the tags, is there untracked memory coming from Engine itself?
Not exactly, but Unreal has been rather loose with greed on memory (and disk space), so for a highly constrained project I just made my own engine.
A few random things:
I did find that the deferred renderer in general (along with its many options like virtual maps) takes up quite a lot of memory especially if you use a lot of the graphical features that came with UE5*
*
UE also creates an instance of every UObject for its CDO and runs the constructor for that UObject. That means if you have some heavy memory UObjects that take up that memory before BeginPlay or Spawn, Unreal has at least one of each of those sitting in memory at the moment it launches.
There were / are some bugs related to untracked memory usage by the engine