1# Profiling WebAssembly
2
3One of WebAssembly's major goals is to be quite close to native code in terms of
4performance, so typically when executing Wasm you'll be quite interested in how
5well your Wasm module is performing! From time to time you might want to dive a
6bit deeper into the performance of your Wasm, and this is where profiling comes
7into the picture.
8
9For best results, ideally you'd use hardware performance counters for your
10timing measurements. However, that requires special support from your CPU and
11operating system. Because Wasmtime is a JIT, that also requires hooks from
12Wasmtime to your platform's native profiling tools.
13
14As a result, Wasmtime support for native profiling is limited to certain
15platforms. See the following sections of this book if you're using these
16platforms:
17
18- On Linux, we support [perf](./examples-profiling-perf.md).
19
20- For Intel's x86 CPUs on Linux or Windows, we support
21  [VTune](./examples-profiling-vtune.md).
22
23- For everything else, see the cross-platform profiler below.
24
25The native profilers can measure time spent in WebAssembly guest code as well as
26time spent in the Wasmtime host and potentially even time spent in the kernel.
27This provides a comprehensive view of performance.
28
29If the native profiling tools don't work for you, Wasmtime also provides a
30[cross-platform profiler](./examples-profiling-guest.md). This profiler can only
31measure time spent in WebAssembly guest code, and its timing measurements are
32not as precise as the native profilers. However, it works on every platform that
33Wasmtime supports.
34