Better Way To Profile PhysX In UE4


It still remains hard to profile PhysX when you are developing a UE4 project. Of course you can use Heat Maps(For Linux) or StreamLines(for Android) to get very in-depth performance data like:


This tools can really help a lot to find performance hotspots. But pvd should be used if you want to digging into PhysX since measuring scope performance is pretty common during performance profile.

How Does UE4 Handle PVD?

UE4 handles PVD using GPhysXVisualDebugger, which is created in InitGamePhysCore function. You need to call PvdConnect function by console command to connect to PhysX Visual Debugger running on your local machine like:

pvd connect localhost

But there is a huge limitation with this method—You cannot easily collect PVD data on dedicated server or mobile device.

Streaming To File

Obviously, it would be much better to streaming pvd data to a file, which can be loaded later in PVD.

Global Parameters Setup

Instead of simply creating two functions to handle connection, we choose to create two Global Parameters, GConnecttoPVD and GDisconnectFromPVD since we want to handle pvd connection in FPhysScene_PhysX::StartFrame().

You may also handle connection in other stages as well. But I still recommend FPhysScene_PhysX::StartFrame() because PVD is known as easy to crash.


And there is a hint: We might want to name our file by date like:

FString TextToSave = FDateTime::Now().ToString();

So, we can connect to PVD file like:

PxPvdTransport* transport = PxDefaultPvdFileTransportCreate(TCHAR_TO_ANSI(*TextToSave));
GPhysXVisualDebugger->connect(*transport, PxPvdInstrumentationFlag::eALL );

Here, PxPvdInstrumentationFlag::eALL means streaming everything, which includes profile, memory and even all visualized debug data, to your file. Hence this cause a very large file, and it is very easy to crash during loading this file.

Thus, I personally recommend to specify PxPvdInstrumentationFlag::ePROFILE only when creating PVD file.

And as for disconnecting from PVD, we simply call:


And it’s done!

Recommended Way To Connect&Disconnect

Personally, I love to specify two timers to manually handle PVD connections by FParse::Value(FCommandLine::Get(), TEXT("-PVDTimer="), Value).

Try to avoid connecting to PVD at start to prevent crash. Sigh…

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