Re: [PATCH 1/19] MUTEX: Introduce simple mutex implementation

[David Howells]

David Howells <[EMAIL PROTECTED]> wrote:

> > Any reason why you're setting up your own style of waitqueue in
> > mutex-simple.c instead of just using the kernel's style of waitqueue?
> 
> Because I can steal the code from FRV's semaphores or rw-semaphores, and this
> way I can be sure of what I'm doing.

And because:

        struct mutex {
                int                     state;
                wait_queue_head_t       wait_queue;
        };

Wastes 8 more bytes of memory than:

        struct mutex {
                int                     state;
                spinlock_t              wait_lock;
                struct list_head        wait_list;
        };

on a 64-bit machine if spinlock_t is 4 bytes. Both waste 4 bytes if spinlock_t
is 8 bytes.

David