Event::set_value not needed?

[zcbenz]

The mlx::core::Event class supports setting signaled value, but mlx code always set the value to 1:

mlx/mlx/transforms.cpp

Line 193 in 117e135

e->second.set_value(1);

If I remove the Event::set_value method, and reimplement Event::wait/signal with std::atomic::wait/notify_all, would Event still function the same?

(I'm asking this because it seems that with CUDA's synchronization library the only way to implement mlx::core::Event is with cuda::std::atomic.)

[awni]

We don't use the value anymore.. that is a recent change though. I preserved the ability to set the value since it could be useful if we want to switch to more fine-grained synchronization (for example synchronizing on individual arrays rather than the entire graph).

You should be able to implement it with the value using atomic wait and notify. The thread that's waiting has to atomically check if the current value is greater or equal to it's required value before it can stop waiting.

[awni]

See for example the CPU implementation of Event which only uses a mutex and condition variable but has the same functionality.

[zcbenz]

Thanks!