Memory profiling question: "Used Total" vs "Total System Memory Usage"

Hi @SullyTheStrange,

Thanks for the question! I'll explain memory stats here.

Unity Editor and Players internally use pools for all memory allocations. E.g. when allocating 16 bytes we ask system to allocate 4MB (in the Player) or 16MB (in the Editor) block and then all subsequent allocations use that memory. If block is full, we allocate another one and if it's empty we return it to the system. This technique is used to improve performance and reduce fragmentation.
And also this makes stats a bit confusing.

Used Total - memory used right now if we don't take pools and allocation headers data into account. Essentially it is sum of all internally managed allocations which are not freed yet. Profiler.GetTotalAllocatedMemoryLong is the Scripting API getter.

Reserved Total - is how much we took from the system. This includes all allocated memory including pools and extra allocation headers. In our case it is commit memory - we allocate on heap (reserve+commit). Includes Used Total. Scripting API equivalent - Profiler.GetTotalReservedMemoryLong.

Total System Memory Usage - total size of used (commit) memory by Unity process. This includes everything what is used by the process - Reserved Total + executable's images (code and data). It is PrivateUsage of PROCESS_MEMORY_COUNTERS_EX on Windows.

Taking this into account in your case I would say that if Reserved Total >1GB player might definitely run out of memory on end-goal device. If TSMU>1GB system might page some some memory to disk, but that's not guaranteed and it might make performance horrible. So it is always safer to have TSMU<1GB.
I would say TSMU is what should be mentioned as Required Memory in System Requirements for your game.
(That's assuming you have TSMU data from the player.)

 

Hi @jiwansu internally we use the same API for reporting the memory of a render texture to the snapshot. Are you perhaps looking at the whole RenderTexture category in the TreeMap instead of the individual items inside?

 

I misunderstood the question as related to the RenderTexture

Profiler.GetTotalAllocatedMemoryLong() returns the memory used by Unity and tracked by Unity. The closest equivalent in memory stats area is "Unity:". Which is -

Unity: 38.7MB = Profiler.GetTotalAllocatedMemoryLong() + "untracked memory" - Profiler - FMOD - Video

, where "untracked memory" are allocations done by some thirdparty libraries and OS.

This is messy, yes and right now we are fixing it with a new memory profiler.

 

Not at the moment - but we are working on a new api to query all available profiler stats in the Editor and Player.
(*We do have atm only undocumented

UnityEditor.Profiling.ProfilerDriver.GetOverviewText(ProfilerArea profilerArea, int frame)

which you can use in the Editor to get the whole memory stats text with ProfilerArea.Memory and parse - but not simple and clear getters for stats you mentioned).

 

In the Editor or Player? It is normal for the Editor, not so for a Player

 

Resources.UnloadUnusedAssets might cause Reserved Total to decrease. As mentioned above Unity uses under the hood allocators which use larger memory pools for small allocations (e.g. 4MB blocks for allocations up to 1MB). The 4MB block is returned to the system only if it doesn't contain any used small allocations within. Returning such block would reduce Reserved Total. Unfortunately memory fragmentation might happen if resources with different lifetime are loaded together. And then large block can be stuck for some time until major cleanup happens (e.g. loading new scene exclusively).

If you have a leak then both values should grow synchronously you can use any of those.

 

Could you please capture detailed snapshot to see if there is more information available.
Also Memory Profiler can help with checking out native memory usage.

From the screen you've provided I can see that both native and managed allocations tracked by profiler can't contribute to the system memory usage. Do you happen to use native plugins which allocate memory or similarly java level code which allocates?

 

Both are real. The Total value is the Total value as tracked by Unity's memory manager. The TSMU is the Total Memory that the OS reports as belonging to the Unity application; that includes Memory allocated in native Plugins that you might be using such as WWise, FMod, basically anything in your Plugins folder. The native Memory allocated by these plugins is not reported to Unity's memory manager and therefore can't be part of the Total number.

 

Thanks for the bug report, we'll look into it. We want the TSMU to be as closely as possible alligned with what the Platform profilers or Task managers report.

Sorry the bug got initially closed by QA, it's a rather recent change that we doubled down on getting this alligned and supported a cross all our platforms.

If you see my such misalignment on any platform or reports of 0 TSMU, please file another bug report so we can investigate that

 

Sorry, must have missed that thread while trying to get back on top after my vacation. Your TSMU looks roughly in line with the rest of the numbers reported so unless it contradicts what Android specific tooling tells you, it's a bit of a different issue and I don't see the connection to this thread here.

I replied in that thread.

 

We'll be adding these kind of overview numbers to the Memory Profiler package UI and yes it's a gross oversight that they aren't in there already. The initial focus of the tool was more on providing a more in detail and depth view of memory and the high-level overview was neglected on that path.

Sorry, I'm not sure I can follow that question correctly. Do you want to get that value in the Memory Profiler UI or in the runtime? If the former, see above, if the later:

• Profiler.GetTotalAllocatedMemoryLong
• As of 2020.2 ProfilerRecorder API can query the Memory Profiler stats "Total Used Memory" and Total Reserved Memory" and the other stats, some like these high-level counter values even in Release players. We'll be updating the Memory Profiler Module manual page for 2020.2 with more details on these stats either next week or the one after that.

That kinda depends on how that particular platform counts your memory usage. Usually, Reserved Total is going to be closer to what the platform considers as used memory, because it includes the pre-allocated buffers. And Total System Used Memory is what the OS itself says the app is taking (except for Android where it is currently the total memory used on the entire phone by any app and in the fix will be the Residual shared memory, because starting from Oreo, getting the total app used size from the OS comes at a steep price of ~500ms per request...)

 

Hi @chrismarch !

2020.2.0b8 has a fix for TSMU
On Android we use rss stat obtained via proc/self/statm as this seems to be the fastest and most complete memory information. On iOS it is resident_size of TASK_BASIC_INFO
The fix patches TSMU value in Profiler Window and ProfilerRecorder api (ProfilerCategory.Memory, "System Used Memory" counter).

android:os:Debug::GetMemoryInfo

is more accurate, but latency in my tests were around 100ms to get the data, so I've fallen back to much faster rss option.

 

We have plans to add a total device memory, so that together with "System Used Memory" (TSMU) that can give you better gauge of how much of system memory Unity app uses. (The C# api for that will be ProfilerRecorder api.)

 

By reducing the memory used for any of the other categories that add up to the total, e.g. Audio, Graphics and any textures etc... This broad a question can not be answered without further details. Some of those details can be obtained via the Memory Profiler, some (like Untracked Memory) may need platform specific Profiling tools to dig deeper for details, until our Memory Profiler is tracking everything.

Sidenote: Updating to the latest 2019.4.x version may be beneficial for more details when using the memory profiler.

 

Hi @IluhaRud !

You can use "System Used Memory" counter (available since 2021.2). E.g. like

Code (CSharp):

1. using System.Text;
2. using Unity.Profiling;
3. using UnityEngine;
4.  
5. public class MemoryStatsScript : MonoBehaviour
6. {
7.     string statsText;
8.     ProfilerRecorder totalReservedMemoryRecorder;
9.     ProfilerRecorder gcReservedMemoryRecorder;
10.     ProfilerRecorder systemUsedMemoryRecorder;
11.  
12.     void OnEnable()
13.     {
14.         totalReservedMemoryRecorder = ProfilerRecorder.StartNew(ProfilerCategory.Memory, "Total Reserved Memory");
15.         gcReservedMemoryRecorder = ProfilerRecorder.StartNew(ProfilerCategory.Memory, "GC Reserved Memory");
16.         systemUsedMemoryRecorder = ProfilerRecorder.StartNew(ProfilerCategory.Memory, "System Used Memory");
17.     }
18.  
19.     void OnDisable()
20.     {
21.         totalReservedMemoryRecorder.Dispose();
22.         gcReservedMemoryRecorder.Dispose();
23.         systemUsedMemoryRecorder.Dispose();
24.     }
25.  
26.     void Update()
27.     {
28.         var sb = new StringBuilder(500);
29.         if (totalReservedMemoryRecorder.Valid)
30.             sb.AppendLine($"Total Reserved Memory: {totalReservedMemoryRecorder.LastValue}");
31.         if (gcReservedMemoryRecorder.Valid)
32.             sb.AppendLine($"GC Reserved Memory: {gcReservedMemoryRecorder.LastValue}");
33.         if (systemUsedMemoryRecorder.Valid)
34.             sb.AppendLine($"System Used Memory: {systemUsedMemoryRecorder.LastValue}");
35.         statsText = sb.ToString();
36.     }
37.  
38.     void OnGUI()
39.     {
40.         GUI.TextArea(new Rect(10, 30, 250, 50), statsText);
41.     }
42. }

(more info at https://docs.unity3d.com/2022.2/Documentation/Manual/ProfilerMemory.html)