Re: [take25 1/6] kevent: Description.

Evgeniy Polyakov
2006-11-24T11:03:00Z

On Thu, Nov 23, 2006 at 11:45:36AM -0800, Ulrich Drepper (drepper@redhat.com) wrote:
> Evgeniy Polyakov wrote:
> >Kernel does not put there a new entry, it is only done inside
> >kevent_wait(). Entries are put into queue (in any context), where they can
> >be obtained
> >from only kevent_wait() or kevent_get_events().
>
> I know this is how it's done now. But it is not where it has to end.
> IMO we have to get to a solution where new events are posted to the ring
> buffer asynchronously, i.e., without a thread calling kevent_wait. And
> then you need the extra parameter and verification. Even if it's today
> not needed we have to future-proof the interface since it cannot be
> changed once in use.

There is a special flag in kevent_user to wake it if there are no ready
events - kernel thread which has added new events will set it and thus
subsequent kevent_wait() will return with updated indexes - userspace
must check indexes after kevent_wait().

> --
> ➧ Ulrich Drepper ➧ Red Hat, Inc. ➧ 444 Castro St ➧ Mountain View,
> CA ❖

--
Evgeniy Polyakov