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On Fri, 16 Dec 2005, Joe Korty wrote: > > The Mars Pathfinder incident is sufficient proof that some solution to > the priority inversion problem is required in real systems. Ehh. The Mars Pathfinder is just about the worst case "real system", and if I recall correctly, the reason it was able to continue was _not_ because it handled priority inversion, but because it reset itself every 24 hours or something like that, and had debugging facilities.. The _real_ lesson you should take away from it is not that priority inheritance is a good solution to priority inversion, but that having a failsafe switch when everthing goes wrong is critical. You don't know _what_ bug you'll encounter. The bug itself could have been solved without priority inheritance, although I think in this case enabling that in VxWorks was the particular solution to the problem as being the least invasive. Personally, I don't care what user space does. If some app wants to use priority inheritance to solve its bugs, that's fine. But it's like recursive locks: it's generally a _bandaid_ for bad locking. I definitely don't want the kernel depending on either. So put a watchdog on your critical systems, and make sure you can debug them. Especially if they're on Mars. Linus - To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/ | ||||||||||||
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