Added random scheduling #4272
Added random scheduling #4272
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@rustbot ready |
| self.active_thread = id; | ||
| break; | ||
| } | ||
| .chain(self.threads.iter_enumerated().take(self.active_thread.index() + 1)) |
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this is to include the current thread as well in the vec. So that it can also be randomly scheduled as well.
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Doesn't round robin scheduling get stuck on the same thread then possibly if the current thread is also the first thread? Or does yielding mark it as not ready so this was always just an optimization on master?
Either way, just remove the chain and take and thus just iterate all threads always?
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Doesn't round robin scheduling get stuck on the same thread then possibly if the current thread is also the first thread?
if the current thread is the first it means that all the other threads are terminated or blocked. So it is fine to schedule it again ig.
Or does yielding mark it as not ready so this was always just an optimization on master?
No I dont think yielding marks it as not ready.
src/bin/miri.rs
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| miri_config.fixed_scheduling = true; | ||
| miri_config.preemption_rate = 0.0; |
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We should just not auto-preempt when fixed_scheduling is set, so we don't have to set two fields here.
src/machine.rs
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| let mut threads = ThreadManager::default(); | ||
| threads.set_round_robin_scheduling(config.fixed_scheduling); |
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Instead of such a setter, please add a ThreadManager::new method that takes &MiriConfig as argument.
src/concurrency/thread.rs
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| .filter(|(_id, thread)| thread.state.is_enabled()) | ||
| .collect::<Vec<_>>(); | ||
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| let mut new_thread = threads.first(); |
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Also here, please don't use an initialize-then-mutate pattern. It's almost always better to initialize things with the right value immediately and eschew mutation. So here that would be let new_thread = if self.round_robin_scheduling { ... } else { ... }.
src/concurrency/thread.rs
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| .filter(|(_id, thread)| thread.state.is_enabled()) | ||
| .collect::<Vec<_>>(); | ||
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| let mut new_thread = threads.first(); |
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Since you are now adding the current thread, this can never be None.
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but the current thread can be in terminated stated or blocked state. So this can be None.
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| if let Some((id, _thread)) = new_thread { |
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If the randomized scheduler picks the original thread again, we'll still enter this codepath and print the "thread switched" marker.
Closes #4230.