tracy/examples/RocprofOnDemandRepro

Rocprofiler On-Demand Profiling Repro

Demonstrates that unpatched Tracy crashes when a profiler connects to a HIP application built with TRACY_ON_DEMAND and TRACY_ROCPROF.

Root cause

Three bugs in TracyRocprof.cpp break on-demand profiling:

1. GpuNewContext not deferred. gpu_context_allocate() writes a GpuNewContext queue item but does not call DeferItem(). When a Tracy client connects late, the context creation message is never replayed. The server then receives GpuZoneBegin events for a context it has never seen, triggering:

   Assertion `ctx' failed in ProcessGpuZoneBeginImplCommon
   

2. GpuContextName not deferred. Same function writes the context name ("rocprofv3") without calling DeferItem(). Even after fixing bug 1, a late-connecting client sees the GPU context but it appears unnamed in the profiler. Use check_gpu_ctx_name to verify.

3. Kernel symbols dropped before init. The data->init guard at the top of tool_callback_tracing_callback() blocks all callbacks before the GPU context is allocated. Kernel symbol registrations (CODE_OBJECT_DEVICE_KERNEL_SYMBOL_REGISTER) happen at HIP init time — before data->init is true — so they are silently dropped. Even if the crash is worked around, kernel names would be missing.

Prerequisites

• AMD GPU with working ROCm driver
• librocprofiler-sdk.so available (typically at /opt/rocm/lib/)
• /opt/rocm/bin/hipcc

Build and run

make
./repro &
tracy-capture -o repro.tracy -s 5

Verifying the context name

check_gpu_ctx_name loads a .tracy file and prints the GPU context names. Build it against the Tracy server library (e.g. from a capture build directory) and run:

./check_gpu_ctx_name repro.tracy
# Expected (patched):   "GPU context 0: rocprofv3"
# Expected (unpatched): "GPU context 0: (unnamed)"

Exit codes: 0 = all contexts named, 2 = unnamed context found.

What to expect

Tracy version	Result
Unpatched	tracy-capture crashes: Assertion 'ctx' failed
Patched (GpuNewContext only)	Capture succeeds but GPU context is unnamed
Fully patched	Capture succeeds with ~50 GPU zones and context named "rocprofv3"