Linked by Hadrien Grasland on Wed 25th May 2011 05:42 UTC
Hardware, Embedded Systems I'm going to become short of suitable title suffixes pretty shortly... Anyhow, I have also reviewed interrupts on the MOS 6502 for the sake of extreme completeness, bust most importantly have tried to address some very incomplete and misleading statements of the interrupt handling model about pop-up threads and service-providing processes in a rather extensive way, see this post.
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Alfman
Member since:
2011-01-28

Neolander,

"Anyway, now I understand what you're talking about, but not what's the problem with mixing async and threads yet. So I move on... "

I'm having trouble parsing your sentence. Are you asking if IO async can be mixed with IO threads?

Yes, but it'd need to be somewhat indirect since the async model isn't supposed to block on semaphores/mutex.

The async process could call a variant of the mutex which polls rather than blocks, but that's not really acceptable. Ideally we'd have a variant of the mutex (compatible with the mutex used by threads) which signals when it's ready instead of blocking and waiting.

A userspace app could emulate these signals by employing a thread wrapper to grab a blocking mutex, then send a signal to the async thread upon it's acquisition. However this is totally inefficient since we're doing even more work than the pure threaded solution.

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