Linked by Hadrien Grasland on Thu 19th May 2011 21:31 UTC
Hardware, Embedded Systems Having read the feedback resulting from my previous post on interrupts (itself resulting from an earlier OSnews Asks item on the subject), I've had a look at the way interrupts work on PowerPC v2.02, SPARC v9, Alpha and IA-64 (Itanium), and contribute this back to anyone who's interested (or willing to report any blatant flaw found in my posts). I've also tried to rework a bit my interrupt handling model to make it significantly clearer and have it look more like a design doc and less like a code draft.
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RE[6]: Pop-up threads
by Alfman on Tue 24th May 2011 20:09 UTC in reply to "RE[5]: Pop-up threads"
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"Actually, you have this problem even if you have several distinct async drivers running side by side. As soon as there are shared resources, there is a synchronization overhead."

I wasn't careful with my wording, we can run many instances of the async model within multiple threads and/or processes, which can communicate to each other using lock free message queues. So although they can share certain resources this way, it's not a shared resource in the traditional "I hold the mutex" sense.

"Joking aside, I think that anything that requires some reactivity (and most drivers are included) should never, ever, depend on blocking file I/O."

I agree with you, but you do realize that this is how nearly all IO is handled in linux?

"Are all drivers fundamentally serial in nature and doing little processing ?"

I was responding to your comment about using MT graphics rendering, which I agree could benefit. However many devices are inherently serial.

"Some time ago, I was wondering about an efficient way to do an FTIR touchscreen driver."

Hey I built one myself! Drilled LED holes into a picture frame, except I used visible light.

"Blob detection and tracking might work first by locating blobs in the initial pictures the brute-force way"

That's a delightful project, I built something very similar in college, but they took down the project page. This is exactly the kind of thing I wanted to do with my degree!

"Interesting problem, actually. I think once one thread starts to hog the memory bus like this, we're doomed anyway".

Yes, but the point of my example was that IO bound processes don't benefit by running in parallel since they can displace CPU bound processes which do run in parallel. We already seem to agree on this point.

Edited 2011-05-24 20:18 UTC

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