Re: [PATCH] Replace completions with semaphores

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From: Ingo Oeser

Subject: Re: [PATCH] Replace completions with semaphores

Date: Saturday, April 12, 2008 - 3:31 am

Hi Daniel,

On Saturday 12 April 2008, Daniel Walker wrote:
quoted text> From my perspective it should be keep completions , and remove
> semaphores.. The problem with semaphores is the lack of a strict API, 
> and loose usage. 

Seconded!

Ask any software engineer, to describe what a semaphore is and
how it behaves. You'll get the full spectrum of possible semaphore
implementation options. Ask any advanced software engineer and he'll
ask "What kind of semaphore?".

So let them die ASAP!

quoted text> At times I've spent hours trying to figure out what a semaphore 
> is doing, or suppose to be doing. 

Same here. Or figuring out what kind of semphore behavior the developer
expected.

quoted text> If we enforce strict usage of semaphores, then we'll basically reproduce
> mutex usage, and we have a generic mutex already..

Or have different API for using the same semaphores in different 
creative ways. It might be hard to implement lockdep for that :-)

No, I'm happy that Linux has so many more advanced concurrency concepts,
that the pre-dinosaur locking mechanism (semaphore) is usually 
the last on your list.

Best Regards

Ingo Oeser
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Messages in current thread:

[PATCH] Replace completions with semaphores, Matthew Wilcox, (Fri Apr 11, 2:00 pm)

Re: [PATCH] Replace completions with semaphores, Daniel Walker, (Fri Apr 11, 11:43 pm)

Re: [PATCH] Replace completions with semaphores, Ingo Oeser, (Sat Apr 12, 3:31 am)

Re: [PATCH] Replace completions with semaphores, Peter Zijlstra, (Sat Apr 12, 5:24 am)

Re: [PATCH] Replace completions with semaphores, Matthew Wilcox, (Sat Apr 12, 10:26 am)

Re: [PATCH] Replace completions with semaphores, Daniel Walker, (Sat Apr 12, 11:01 am)

Re: [PATCH] Replace completions with semaphores, Peter Zijlstra, (Sat Apr 12, 11:05 am)

Re: [PATCH] Replace completions with semaphores, Matthew Wilcox, (Sat Apr 12, 12:04 pm)

Re: [PATCH] Replace completions with semaphores, Peter Zijlstra, (Sat Apr 12, 12:16 pm)

Re: [PATCH] Replace completions with semaphores, Roland Dreier, (Sat Apr 12, 12:53 pm)

Re: [PATCH] Replace completions with semaphores, Matthew Wilcox, (Sat Apr 12, 1:47 pm)

Re: [PATCH] Replace completions with semaphores, Ingo Molnar, (Sun Apr 13, 12:05 am)

Re: [PATCH] Replace completions with semaphores, Ingo Molnar, (Sun Apr 13, 12:08 am)

Re: [PATCH] Replace completions with semaphores, Matthew Wilcox, (Sun Apr 13, 5:52 am)

Re: [PATCH] Replace completions with semaphores, Matthew Wilcox, (Sun Apr 13, 5:57 am)

Re: [PATCH] Replace completions with semaphores, Bart Van Assche, (Sun Apr 13, 6:55 am)

Re: [PATCH] Replace completions with semaphores, Matthew Wilcox, (Sun Apr 13, 7:22 am)

Re: [PATCH] Replace completions with semaphores, Bart Van Assche, (Sun Apr 13, 7:55 am)

Re: [PATCH] Replace completions with semaphores, Ingo Molnar, (Mon Apr 14, 8:39 am)

Re: [PATCH] Replace completions with semaphores, Ingo Molnar, (Mon Apr 14, 8:41 am)

Re: [PATCH] Replace completions with semaphores, Roland Dreier, (Mon Apr 14, 8:58 am)

Re: [PATCH] Replace completions with semaphores, Peter Zijlstra, (Mon Apr 14, 9:32 am)

Re: [PATCH] Replace completions with semaphores, Jens Axboe, (Mon Apr 14, 9:54 am)

Re: [PATCH] Replace completions with semaphores, Arjan van de Ven, (Mon Apr 14, 9:56 am)

Re: API documentation (was [PATCH] Replace completions wit ..., Jonathan Corbet, (Mon Apr 14, 10:12 am)

Re: API documentation (was [PATCH] Replace completions wit ..., Peter Zijlstra, (Mon Apr 14, 10:33 am)

Re: [PATCH] Replace completions with semaphores, Andi Kleen, (Mon Apr 14, 10:46 am)

Re: [PATCH] Replace completions with semaphores, Matthew Wilcox, (Mon Apr 14, 10:46 am)

Re: [PATCH] Replace completions with semaphores, Matthew Wilcox, (Mon Apr 14, 10:50 am)

Re: [PATCH] Replace completions with semaphores, Peter Zijlstra, (Mon Apr 14, 10:54 am)

Re: [PATCH] Replace completions with semaphores, Daniel Walker, (Mon Apr 14, 11:09 am)

Re: API documentation (was [PATCH] Replace completions wit ..., Bart Van Assche, (Mon Apr 14, 11:38 am)

Re: [PATCH] Replace completions with semaphores, Andi Kleen, (Mon Apr 14, 12:16 pm)

Re: [PATCH] Replace completions with semaphores, Alan Cox, (Mon Apr 14, 12:16 pm)

Re: [PATCH] Replace completions with semaphores, Bart Van Assche, (Mon Apr 14, 11:18 pm)

Re: [PATCH] Replace completions with semaphores, Peter Zijlstra, (Mon Apr 14, 11:46 pm)

Re: [PATCH] Replace completions with semaphores, Bart Van Assche, (Tue Apr 15, 12:17 am)

Re: [PATCH] Replace completions with semaphores, Peter Zijlstra, (Tue Apr 15, 1:44 am)

Re: [PATCH] Replace completions with semaphores, Bart Van Assche, (Tue Apr 15, 6:15 am)

Re: [PATCH] Replace completions with semaphores, Linus Torvalds, (Tue Apr 15, 9:09 am)

Re: [PATCH] Replace completions with semaphores, Andi Kleen, (Tue Apr 15, 9:27 am)

Re: [PATCH] Replace completions with semaphores, Linus Torvalds, (Tue Apr 15, 9:57 am)

Re: [PATCH] Replace completions with semaphores, Ingo Molnar, (Tue Apr 15, 10:05 am)

Re: [PATCH] Replace completions with semaphores, Andi Kleen, (Tue Apr 15, 10:15 am)

Re: [PATCH] Replace completions with semaphores, Linus Torvalds, (Tue Apr 15, 10:26 am)

Re: [PATCH] Replace completions with semaphores, Matthew Wilcox, (Tue Apr 15, 10:41 am)

Re: [PATCH] Replace completions with semaphores, Linus Torvalds, (Tue Apr 15, 11:14 am)

Re: [PATCH] Replace completions with semaphores, Matthew Wilcox, (Tue Apr 15, 11:50 am)

Re: [PATCH] Replace completions with semaphores, Ingo Molnar, (Wed Apr 16, 5:37 am)

Re: [PATCH] Replace completions with semaphores, Andi Kleen, (Wed Apr 16, 5:50 am)

Killable stat/readdir, Matthew Wilcox, (Wed Apr 16, 5:59 am)

Re: [PATCH] Replace completions with semaphores, Ingo Oeser, (Wed Apr 16, 9:07 am)

Re: [PATCH] Replace completions with semaphores, Matthew Wilcox, (Wed Apr 16, 9:16 am)

Re: [PATCH] Replace completions with semaphores, Oliver Neukum, (Wed Apr 16, 9:31 am)

Re: [PATCH] Replace completions with semaphores, Matthew Wilcox, (Wed Apr 16, 9:34 am)

Re: [PATCH] Replace completions with semaphores, Oliver Neukum, (Wed Apr 16, 9:42 am)

Re: [PATCH] Replace completions with semaphores, Matthew Wilcox, (Wed Apr 16, 9:44 am)

Re: [PATCH] Replace completions with semaphores, Roland Dreier, (Wed Apr 16, 9:47 am)

Re: [PATCH] Replace completions with semaphores, Arjan van de Ven, (Wed Apr 16, 9:50 am)

Re: [PATCH] Replace completions with semaphores, Matthew Wilcox, (Wed Apr 16, 9:58 am)

Re: [PATCH] Replace completions with semaphores, Arjan van de Ven, (Wed Apr 16, 10:08 am)

Re: [PATCH] Replace completions with semaphores, Matthew Wilcox, (Wed Apr 16, 10:12 am)

Re: [PATCH] Replace completions with semaphores, Matthew