Heap allocation profiling for Zircon kernel. It captures live allocations at any point in time and export that in a pprof-compatible protobuf format.
To enable zircon heap profiler append --args kernel_memory_profiler=true and --with src/performance/memory/heapdump/kernel-collector to the fx set invocation.
Note: Kernel memory profiler and HEAP_COLLECT_STATS are mutually exclusive.
Use ffx component run to launch this component into any realm that can read bootfs:
ffx component run /core/ffx-laboratory:kernel-collector fuchsia-pkg://fuchsia.com/kernel-collector#meta/kernel-collector.cm
Then collect a profile with:
fx ffx profile heapdump snapshot --by-koid 1 --output-file /tmp/profile.pb
This outputs a serialized perftools.profiles.Profile protocol buffer, that can be turned into a flame graph with:
fx pprof -flame /tmp/profile.pb
You can verify the kernel profile buffer size by inspecting the logs:
fx log --filter kernel-collector
The buffer size can be modified in //zircon/kernel/lib/heap/heap_wrapper.cc.