Subject: Re: [1/4] kevent: core files.

From: Benjamin LaHaise <[email-masked]>
Date: Fri, 23 Jun 2006 16:31:14 -0400

On Fri, Jun 23, 2006 at 01:19:40PM -0700, David Miller wrote:
> I completely agree with Evgeniy here.
> 
> There is nothing in the kernel today that provides integrated event
> handling.  Nothing.  So when someone says to use the "existing" stuff,
> they need to have their head examined.

The existing AIO events are *events*, with the syscalls providing the 
reading of events.

> The existing AIO stuff stinks as a set of interfaces.  It was designed
> by a standards committee, not by people truly interested in a good
> performing event processing design.  It is especially poorly suited
> for networking, and any networking developer understands this.

I disagree.  Stuffing an event that a read or write is complete/ready is a 
good way of handling things, even more so with hardware that will perform 
the memory copies to/from user buffers.

> It is pretty much a foregone conclusion that we will need new
> APIs to get good networking performance.  Every existing interface
> has one limitation or another.

Eh?  Nobody has posted any numbers comparing the approaches yet, so this 
is pure handwaving, unless you have real concrete results?

> So we should be happy people like Evgeniy try to work on this stuff,
> instead of discouraging them.

I would like to encourage him, but at the same time I don't want to see 
creating APIs that essentially duplicate existing work and needlessly 
break compatibility.  I completely agree that the in-kernel APIs are not 
as encompassing as they should be, and within the kernel Evgeniy's work 
may well be the way to go.  What I do not agree is that we need new 
syscalls at this point.  I'm perfectly willing to accept proof that change 
is needed if we do a proper comparision between any new syscall API and the 
use of the existing syscall API, but the pain of introducing a new API is 
sufficiently large that I think it is worth looking at the numbers.

		-ben
-- 
"Time is of no importance, Mr. President, only life is important."
Don't Email: <[email-masked]>.