Re: Improving (network) IO performance ...

[Davide Libenzi]

On 12-Jul-2001 Dan Kegel wrote:
> Very cool.  Thanks for doing a no-scan implementation of /dev/poll!
> Two questions:
> 
> 1) have you compared its performance against Vitaly Luban's 
> signal-per-fd patch?  Even though it's realtime-signal based,
> there's some hope for it being quite efficient.  See
> http://www.luban.org/GPL/gpl.html and
> http://boudicca.tux.org/hypermail/linux-kernel/2001week20/1353.html

There's more than the event collapsing inside the patch.
I saw the Luban's work but I decided to use the Lever-Provos /dev/poll as a
performance meter ( and the old poll() obviously ).
This coz I read papers where RT signals implementations resulted to have less
performance when compared to /dev/poll.

> 2) A little birdie told me that someone had gotten a freebsd
> box to handle something like half a million connections.
> I would like to see you extend the horizontal axis of your graph
> by a couple orders of magnitude :-)

Here You can find the new statistics with 16000 connections :

http://www.xmailserver.org/linux-patches/nio-improve.html

I cannot reach that number of connections of the test machine coz the socket
buffer space will eat all my memory ( 128 Mb ).
Anyway the graph speaks quite clear about the tendency to greater numbers of
connections.

> p.s. I have updated http://www.kegel.com/c10k.html#nb./dev/poll
> with a link to your report.

Thanks, the page is a work in progress anyway.

- Davide