# Cachegrind Client Requests
Interface to [Cachegrind Client Requests][vg-docs] defined in
`valgrind/cachegrind.h`.
These requests enable isolated profiling by combining the
[--instr-atstart][instr-atstart] flag with
[`start_instrumentation`](start_instrumentation) and
[`stop_instrumentation`](stop_instrumentation) to delimit specific measurement
regions.
## Usage
Nothing happens unless the binary runs under Cachegrind:
> ```text
> :~$ cargo build
> :~$ valgrind --tool=cachegrind target/debug/app
> ```
## Version Requirements
- **Minimum Valgrind:** `3.22`
[instr-atstart]: https://valgrind.org/docs/manual/cg-manual.html#opt.instr-atstart
[vg-docs]: https://valgrind.org/docs/manual/cg-manual.html#cg-manual.clientrequests