Re: /dev/yapoll : Re: [PATCH] /dev/epoll update ...

["Christopher K. St. John" <cks@distributopia.com>]

Davide Libenzi wrote:
> 
> By reporting the initial state of the connection will
> make /dev/epoll to be a hybrid interface
>

 Yes, but you need that anyway (see below)


> and looks pretty crappy to me.
>

 Talk to the people who wrote the paper (and won
"Outstanding Paper" for it at Usenix). The paper
is quite convincing, so I'm afraid I'll have to
disagree. But as I said, I'll know more when I've
tested further.


 It turns out that a hybrid interface is needed
in any case to handle overload. When the queues
start to fill up, you need to back off and start
basically doing something like a plain-old-poll()
instead. Ref the paper. Here's a link to a kernel
list dicussion that covers similiar ground:

  http://kt.linuxcare.com/kernel-traffic/kt20001113_93.epl

 Also, merging events for the same fd, which
everyone seems to agree is a good thing, is
in fact a "hybrid" approach, right? Since 
you're now tracking state (albeit only between
calls to ioctl(EP_POLL).

 I intend to use some of the original Linux
/dev/poll code, as well as some of yours, but
it's a new patch with a new name.


-- 
Christopher St. John cks@distributopia.com
DistribuTopia http://www.distributopia.com