[bkammerd]

This adds --mode=gpu, which profiles EU stalls on Intel GPUs (Xe-based arch) using an external iaprof executable. The collected profile conforms to gProfiler's existing stack-sampling format so that GPU flame graphs can be viewed in an unmodified Performance Studio.

Description

Additions

• IaprofProfiler (gprofiler/profilers/iaprof.py)
• A system profiler registered only for gpu mode.
• Starts a single long-lived iaprof process.
• Requires iaprof 2026.3 or newer, checked with iaprof --version.
• New arguments: --iaprof-path and --iaprof-eu-stall-subsample (default 100).
• IaprofProcess (gprofiler/utils/iaprof_process.py)
• Reads stdout on a background thread and stores the counts per PID.
• gprofiler/utils/iaprof.py parses iaprof's output into per-PID counters.
• CLI (gprofiler/main.py)
• -f/--profiling-frequency sets iaprof's output interval in GPU mode. The default is 100 Hz, which is matches iaprof's default 10 ms interval.
• GPU mode rejects --rootless and --alloc-interval.
• Profile metadata: adds iaprof_version, iaprof_output_interval_ms and iaprof_eu_stall_subsample.
• Tests:
  • tests/test_iaprof.py: parser
  • tests/test_iaprof_process.py: the process management
  • tests/test_iaprof_profiler.py: the profiler subsystem and CLI args

Changes to shared code

• SystemProfilerBase: a new base class for the exclusive system-profiler slot. Perf (SystemProfiler) and IaprofProfiler both inherit from it. It also lets a system profiler add its own profile metadata.
• get_profilers(): selects the system profiler by SystemProfilerBase instead of SystemProfiler. A profiler that doesn't support the current mode is now skipped with a debug log instead of a warning.
• --max-system-processes-for-system-profilers now applies only to perf.
• _snapshot(): local_end_time is now computed after the system-profiler result is collected to fix a bug where in GPU mode, no process profilers ran to take up the snapshot duration, so profiles got identical start and end times.
• Snapshot failure log now prints the name of the system profiler that failed, instead of always mentioning perf.

CPU and allocation modes behave the same as before.

Current Limitations

• iaprof is not bundled. It must be installed separately and selected with --iaprof-path.
• GPU mode runs only one profiler. perf and the language profilers are disabled.
• Starting GPU mode from the Performance Studio doesn't work because Studio's profile_request validation only accepts cpu, allocation and none.
• After an iaprof restart, kernels loaded before the restart may not be attributed.
• Root is required.

Manual Testing

Tested end-to-end on a local machine with an Intel B580 running a simple SYCL matrix multiply benchmark. Test produced flame graphs in a locally-deployed version of the Performance Studio.

[Copilot]

🟡 Changes recommended

Snapshot timeout cleanup can leave stale process and reader state, causing an additional profiling cycle to fail.

1 open finding

• Reap killed child and reset snapshot state after timeout · New

What changed in this PR

Adds Intel Xe GPU EU-stall profiling through an external iaprof process.

Changes:

• Adds GPU profiling mode, CLI options, and metadata.
• Implements iaprof parsing, process lifecycle, and profile generation.
• Generalizes system profilers and adds comprehensive tests.

File	Description
gprofiler/​consts.py	Defines GPU mode and frequency limits.
gprofiler/​main.py	Integrates GPU CLI behavior and metadata.
gprofiler/​profilers/​__init__.py	Exports the Intel GPU profiler.
gprofiler/​profilers/​factory.py	Selects generic system profilers by mode.
gprofiler/​profilers/​iaprof.py	Implements the GPU profiler.
gprofiler/​profilers/​perf.py	Migrates perf to the shared system-profiler base.
gprofiler/​profilers/​profiler_base.py	Introduces SystemProfilerBase.
gprofiler/​utils/​iaprof.py	Parses streamed iaprof records.
gprofiler/​utils/​iaprof_process.py	Manages the long-lived iaprof process.
tests/​test_iaprof.py	Tests output parsing and snapshots.
tests/​test_iaprof_process.py	Tests process lifecycle and recovery.
tests/​test_iaprof_profiler.py	Tests profiler behavior and CLI validation.

🧠 Review effort: Balanced

---

💡 Add a code-review agent skill or configure MCP servers for context-aware, tailored reviews. Learn more in the docs.

[mlim19]

Should we error out if the result is requested to upload to the backend at this time?

[bkammerd]

The result can be uploaded to the backend without issues. It just appears as a CPU flame graph, so we may need to visually differentiate on the performance studio side.

[mlim19]

This is specific to iaprof profiler?

[bkammerd]

No, this covers both perf and iaprof since they are now both considered "system" profilers.

[mlim19]

In general, looks good to me with 2 minor questions