M-Labs/artiq-zynq
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runtime/comms: Faster RPC alloc

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We do busy polling for some time before doing await, for small
allocations we could avoid the context switching and reduce the latency.
This commit is contained in:
pca006132 2020-09-03 12:24:23 +08:00
parent 1931957bc0
commit 56834f152b
1 changed files with 33 additions and 4 deletions
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37
src/runtime/src/comms.rs
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@ -17,7 +17,7 @@ use libboard_zynq::{
},
timer::GlobalTimer,
};
use libcortex_a9::{semaphore::Semaphore, mutex::Mutex};
use libcortex_a9::{semaphore::Semaphore, mutex::Mutex, sync_channel::{Sender, Receiver}};
use futures::{select_biased, future::FutureExt};
use libasync::{smoltcp::{Sockets, TcpStream}, task};
use libconfig::{Config, net_settings};
@ -124,6 +124,35 @@ async fn read_string(stream: &TcpStream, max_length: usize) -> Result<String> {
Ok(String::from_utf8(bytes).map_err(|err| Error::Utf8Error(err.utf8_error()))?)
}
const RETRY_LIMIT: usize = 100;
async fn fast_send(sender: &mut Sender<'_, kernel::Message>, content: kernel::Message) {
let mut content = content;
for _ in 0..RETRY_LIMIT {
match sender.try_send(content) {
Ok(()) => {
return
},
Err(v) => {
content = v;
}
}
}
sender.async_send(content).await;
}
async fn fast_recv(receiver: &mut Receiver<'_, kernel::Message>) -> kernel::Message {
for _ in 0..RETRY_LIMIT {
match receiver.try_recv() {
Ok(v) => {
return v;
},
Err(()) => ()
}
}
receiver.async_recv().await
}
async fn handle_run_kernel(stream: Option<&TcpStream>, control: &Rc<RefCell<kernel::Control>>) -> Result<()> {
control.borrow_mut().tx.async_send(kernel::Message::StartRequest).await;
loop {
@ -143,7 +172,7 @@ async fn handle_run_kernel(stream: Option<&TcpStream>, control: &Rc<RefCell<kern
match host_request {
Request::RPCReply => {
let tag = read_bytes(stream, 512).await?;
let slot = match control.borrow_mut().rx.async_recv().await {
let slot = match fast_recv(&mut control.borrow_mut().rx).await {
kernel::Message::RpcRecvRequest(slot) => slot,
other => panic!("expected root value slot from core1, not {:?}", other),
};
@ -156,8 +185,8 @@ async fn handle_run_kernel(stream: Option<&TcpStream>, control: &Rc<RefCell<kern
0 as *mut ()
} else {
let mut control = control.borrow_mut();
control.tx.async_send(kernel::Message::RpcRecvReply(Ok(size))).await;
match control.rx.async_recv().await {
fast_send(&mut control.tx, kernel::Message::RpcRecvReply(Ok(size))).await;
match fast_recv(&mut control.rx).await {
kernel::Message::RpcRecvRequest(slot) => slot,
other => panic!("expected nested value slot from kernel CPU, not {:?}", other),
}