Re: [PATCH 0/2] eventfd: new EFD_STATE flag

["Michael S. Tsirkin" <mst@redhat.com>]

On Sun, Aug 23, 2009 at 04:40:51PM +0300, Avi Kivity wrote:
> On 08/23/2009 04:36 PM, Michael S. Tsirkin wrote:
>> More important here is realization that eventfd is a mutex/semaphore
>> implementation, not a generic event reporting interface as we are trying
>> to use it.
>>    
>
> Well it is a generic event reporting interface (for example, aio uses it).

Davide, I think it's a valid point.  For example, what read on eventfd
does (zero a counter and return) is not like any semaphore I saw.

Look at eventfd as pipe replacement: for wake-up between processes, it
works well. But what if we want to pass around some kind of key as well?
pipe lets you pass single-byte values atomically. This flag allows us to
use 8 byte values as keys.

> -- 
> error compiling committee.c: too many arguments to function