diff options
Diffstat (limited to 'src/libstd/rt')
| -rw-r--r-- | src/libstd/rt/sched.rs | 14 |
1 files changed, 14 insertions, 0 deletions
diff --git a/src/libstd/rt/sched.rs b/src/libstd/rt/sched.rs index 089c95cd7cd..75b53066441 100644 --- a/src/libstd/rt/sched.rs +++ b/src/libstd/rt/sched.rs @@ -29,6 +29,9 @@ use rt::rtio::{IoFactoryObject, RemoteCallback}; /// on a single thread. When the scheduler is running it is owned by /// thread local storage and the running task is owned by the /// scheduler. +/// +/// XXX: This creates too many callbacks to run_sched_once, resulting +/// in too much allocation and too many events. pub struct Scheduler { /// A queue of available work. Under a work-stealing policy there /// is one per Scheduler. @@ -143,6 +146,10 @@ pub impl Scheduler { fn run_sched_once() { + // First, check the message queue for instructions. + // XXX: perf. Check for messages without atomics. + // It's ok if we miss messages occasionally, as long as + // we sync and check again before sleeping. let sched = Local::take::<Scheduler>(); if sched.interpret_message_queue() { // We performed a scheduling action. There may be other work @@ -153,6 +160,7 @@ pub impl Scheduler { return; } + // Now, look in the work queue for tasks to run let sched = Local::take::<Scheduler>(); if sched.resume_task_from_queue() { // We performed a scheduling action. There may be other work @@ -198,6 +206,12 @@ pub impl Scheduler { self.event_loop.callback(Scheduler::run_sched_once); // We've made work available. Notify a sleeping scheduler. + // XXX: perf. Check for a sleeper without synchronizing memory. + // It's not critical that we always find it. + // XXX: perf. If there's a sleeper then we might as well just send + // it the task directly instead of pushing it to the + // queue. That is essentially the intent here and it is less + // work. match self.sleeper_list.pop() { Some(handle) => { let mut handle = handle; |