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Adding back-off instead of busy-spinning
Also changed the total number of spinning similar to Cilk
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LalehB authored and Clark Gaebel committed Oct 27, 2014
1 parent 005cfed commit b0d1646
Showing 1 changed file with 8 additions and 1 deletion.
9 changes: 8 additions & 1 deletion components/util/workqueue.rs
Expand Up @@ -16,6 +16,7 @@ use std::rand::weak_rng;
use std::sync::atomics::{AtomicUint, SeqCst};
use std::sync::deque::{Abort, BufferPool, Data, Empty, Stealer, Worker};
use std::task::TaskBuilder;
use libc::funcs::posix88::unistd::usleep;

/// A unit of work.
///
Expand Down Expand Up @@ -70,7 +71,7 @@ struct WorkerThread<QueueData, WorkData> {
rng: XorShiftRng,
}

static SPIN_COUNT: uint = 1000;
static SPIN_COUNT: uint = 128;

impl<QueueData: Send, WorkData: Send> WorkerThread<QueueData, WorkData> {
/// The main logic. This function starts up the worker and listens for
Expand All @@ -87,6 +88,7 @@ impl<QueueData: Send, WorkData: Send> WorkerThread<QueueData, WorkData> {
// We're off!
//
// FIXME(pcwalton): Can't use labeled break or continue cross-crate due to a Rust bug.
let mut back_off_sleep = 0 as u32;
loop {
// FIXME(pcwalton): Nasty workaround for the lack of labeled break/continue
// cross-crate.
Expand All @@ -107,10 +109,15 @@ impl<QueueData: Send, WorkData: Send> WorkerThread<QueueData, WorkData> {
}
Data(work) => {
work_unit = work;
back_off_sleep = 0 as u32;
break
}
}

if (i>100) {
unsafe {usleep(back_off_sleep as u32)};
back_off_sleep = back_off_sleep + 5;
}
if i == SPIN_COUNT {
match self.port.try_recv() {
Ok(StopMsg) => {
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