# Metrics operations

libuv provides a metrics API to track the amount of time the event loop has spent idle in the kernel’s event provider.

## API

uint64_t uv_metrics_idle_time(uv_loop_t *loop)

  Retrieve the amount of time the event loop has been idle in the kernel’s event provider (e.g. `epoll_wait`). The call is thread safe.

  The return value is the accumulated time spent idle in the kernel’s event provider starting from when the `uv_loop_t` was configured to collect the idle time.

  Note

  The event loop will not begin accumulating the event provider’s idle time until calling `uv_loop_configure` with `UV_METRICS_IDLE_TIME`.

  New in version 1.39.0.