this post was submitted on 21 Sep 2023
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Programming
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This is a ridiculous definition of "real-time". To accomplish this you'd need to subvert the kernal's scheduler, otherwise you'll always end up with "unbounded" response times since a single program can't control what else is running or which clock cycles are allocated to it. What you end up with is an OS that only runs one process per thread.
Yeah, okay buddy. And I'm tempted to stop eating and sleeping because I'd like the extra free time.
You missed the whole point of the article.
It makes no sense to read the article and arrive at the conclusion that "I need to subvert the Kernel's scheduler". The whole point of the real-time analogy is that handlers have a hard constraint on the time budget allocated to execute each handler. If your handler is within budget them it's perfectly reasonable to run on the UI thread. If your handler exceeds the budget then user experience starts to suffer, and you need to rework your implementation to run stuff async.
Keep in mind that each mouse click/hover/move/sneeze triggers a handler on GUI applications. Clicking on a button can trigger small, instant changes like updating UI, or can trigger expensive operations like running an expensive task. Some handlers start off as doing small UI updates but end up doing more and more stuff that ultimately start to become noticeable.
The article is not talking about async processing. It's talking about the process scheduler and thread blocking. It even has a section titled "Real-time Scheduling" that talks specifically about the process scheduler.
It's simply not possible to fit the author's definition of real-time without using something like an RTOS, and the author seems to understand that. The main feature of an RTOS is a different scheduler implementation that can guarantee cpu time to events. The catch is that an RTOS isn't going to handle general purpose usecases like a personal computer very well since it requires purpose-built programs and won't be great at juggling a lot of different processes at the same time.
No, not really.
The article doesn't even cover process scheduling at all. The whole point of the article, which is immediately obvious to anyone who ever worked on a GUI, is what code runs on event handlers and how doing too much in them has a noticeable detrimental impact on user experience (i.e., blocks the main thread).
It's also obvious to anyone who ever worked on a GUI that you free the main thread of these problems by refactoring the application to run some or all code in a problematic handler asynchronously.