Re: [PATCH] Lightweight userspace semaphores...

[Linus Torvalds]

On Mon, 25 Feb 2002, Alan Cox wrote:
> 
> Any kernel special cases it adds will be unswappable because they are in
> kernel space (not the semaphores here - we want them to be swappable and
> they can be)

Alan, wake up!

I'm talking about anonymous semaphores, the kernel implementation can just 
map a normal anonymous page there.

On 99.9% of all machines out there, you can have semaphores in perfectly 
normal memory.

> When you create a shared mapping by passing -1 to mmap we do

Why are you talking about shared mappings?

The most common case for any fast semaphores are for _threaded_
applications. No shared memory, no nothing.

		Linus