1.2 KiB
Using indirection for faster message passing
Message passing always involves copying the payload from the sender into a
static variable and then from the static variable into the receiver. Thus
sending a large buffer, like a [u8; 128], as a message involves two expensive
memcpys.
Indirection can minimize message passing overhead: instead of sending the buffer by value, one can send an owning pointer into the buffer.
One can use a global memory allocator to achieve indirection (alloc::Box,
alloc::Rc, etc.), which requires using the nightly channel as of Rust v1.37.0,
or one can use a statically allocated memory pool like heapless::Pool.
As this example of approach goes completely outside of RTIC resource
model with shared and local the program would rely on the correctness
of the memory allocator, in this case heapless::pool.
Here's an example where heapless::Pool is used to "box" buffers of 128 bytes.
{{#include ../../../../examples/pool.rs}}
$ cargo run --target thumbv7m-none-eabi --example pool
{{#include ../../../../ci/expected/pool.run}}