Re: [Kiobuf-io-devel] RFC: Kernel mechanism: Compound event wait

[Marcelo Tosatti]

On Tue, 6 Feb 2001, Linus Torvalds wrote:

> 
> 
> On Tue, 6 Feb 2001, Manfred Spraul wrote:
> > Jens Axboe wrote:
> > > 
> > > > Several kernel functions need a "dontblock" parameter (or a callback, or
> > > > a waitqueue address, or a tq_struct pointer).
> > > 
> > > We don't even need that, non-blocking is implicitly applied with READA.
> > >
> > READA just returns - I doubt that the aio functions should poll until
> > there are free entries in the request queue.
> 
> The aio functions should NOT use READA/WRITEA. They should just use the
> normal operations, waiting for requests. The things that makes them
> asycnhronous is not waiting for the requests to _complete_. Which you can
> already do, trivially enough.

Reading write(2): 

       EAGAIN Non-blocking  I/O has been selected using O_NONBLOCK and there was
              no room in the pipe or socket connected to fd to  write  the data
              immediately.

I see no reason why "aio function have to block waiting for requests". 

_Why_ they do ?