| Date | Thu, 21 Oct 2004 13:24:22 -0700 | Subject | Re: [patch] Real-Time Preemption, -RT-2.6.9-rc4-mm1-U8 | From | Bill Huey (hui) <> |
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On Thu, Oct 21, 2004 at 10:14:43PM +0200, Jens Axboe wrote: > On Thu, Oct 21 2004, Bill Huey wrote: > > A lot of things are perfectly "valid" in the Linux kernel regarding > > stuff like that are a bit irregular. But the preemption work about > > to stress these things in ways that was never designed to which is > > why these patches are needed. Having a clear use of various locking > > conventions is key to getting this system to behave in a predictable > > manner. Quite simply, Linux was never targetted to do this and the > > sloppiness is showing so it's got to be removed. > > I have to disagree, I don't think the above use is either convoluted or > sloppy in any way. Now that we have the completion structure, certain > things are surely better implemented as such. But the old use is > perfectly valid and logical, imho.
You use a semaphore to protect data, a completion isn't protecting data but preserving a certain kind of wait ordering in the code. The possibility of overloading the current mutex_t for PI makes for a conceptual mismatch when used in this case since having a kind of priority for completions is a bit odd. It's better to flat out use a completion instead, IMO.
bill
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