Hello,
On 4/4/13 9:15 PM, Richard Fuchs wrote:
Hi,
On 04/04/13 14:58, Daniel-Constantin Mierla wrote:
quite interesting, I didn't know it has two operations modes: user space
forwarding and kernel forwarding.
Is there any plan in supporting more one mode (or dropping the other) in
the future?
Not per se, kernel mode forwarding (at least for the primitive case with
no modifications to the packets) will always be the primary means of
forwarding packets. At the same time, user-space forwarding will also
always be available, since at least the first few packets must always be
processed by the daemon. As such, it doesn't really have two modes of
operation, it will simply fall back to user-space processing if the
kernel modules fails to do its job for whatever reason. It's designed to
use the functionality of the kernel module if possible, but also not to
rely on it.
She fallback to user space can happen even during a call? Or is just
about when the call is initialized, the application detects is some
problem when setting up forwarding rules in the kernel and goes for user
space.
Have you done some measurements to see the benefits of
kernel forwarding vs user space?
I can't quote any specific numbers, but we've seen several times in the
past that the overhead of pushing packets back and forth between kernel
and user space is quite significant. I suppose I could try to set up
some simple tests to get some unscientific ballpark numbers if people
are interested.
Indeed, this is kind of general feeling, at least based on theoretical
aspects, but I haven't seen any kind of numbers just to compare and see
how much is worth to go for kernel forwarding.
Cheers,
Daniel
--
Daniel-Constantin Mierla - http://www.asipto.com
http://twitter.com/#!/miconda - http://www.linkedin.com/in/miconda
Kamailio World Conference, April 16-17, 2013, Berlin
- http://conference.kamailio.com -
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