Re: [PATCH] async poll for 2.5

From: Benjamin LaHaise (bcrl@redhat.com)
Date: Tue Oct 15 2002 - 13:57:31 EST


On Tue, Oct 15, 2002 at 11:53:48AM -0700, Dan Kegel wrote:
> Seems like the thing to do is to move /dev/epoll over to use
> Ben's event system rather than worry about the old /dev/epoll interface.
> But like signal-per-fd, we will want to collapse readiness events,
> which is something Ben's event system might not do naturally.
> (I wouldn't know -- I haven't actually looked at Ben's code.)

If you look at how /dev/epoll does it, the collapsing of readiness
events is very elegant: a given fd is only allowed to report a change
in its state once per run through the event loop. The ioctl that swaps
event buffers acts as a barrier between the two possible reports.

As to how this would interact with the aio event loops, I thought the
"barrier" syscall could be the point at which aio event slots are reserved
and freed. Interest registration would be the other syscall (which would
naturally have to reserve an event for the descriptor in the current set
of readiness notifications). Anyways, just a few thoughts...

                -ben

-- 
"Do you seek knowledge in time travel?"
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