Re: Why userspace rather than writing kernel space modules?
Hi!
I'm a newbie to BIRD who ran across it from freshmeat.net.
Being a newbie, I have some newbie questions.
How efficient is it to sync with kernel space routing tables if the routing tables change rapidly?
Efficient enough.
How often does a routing table change with a typical server configuration and typical server traffic? Lastly besides the portability, why implement a userspace daemon that is required to sync with the kernel when kernel space modules could be written to directly manipulate the routing tables themselves?
Why write X windows when you could integrate them in kernel (like winNT do)? a) portability b) crash-proofness c) bird is swappable d) bird can use libc e) bird is preemptibly-scheduled. If it loops, nothing bad happens. Pavel -- I'm pavel@ucw.cz. "In my country we have almost anarchy and I don't care." Panos Katsaloulis describing me w.r.t. patents at discuss@linmodems.org
On Mon, 11 Jun 2001, Pavel Machek wrote:
Hi!
Hi!
I'm a newbie to BIRD who ran across it from freshmeat.net.
Being a newbie, I have some newbie questions.
How efficient is it to sync with kernel space routing tables if the routing tables change rapidly?
Efficient enough.
How often does a routing table change with a typical server configuration and typical server traffic? Lastly besides the portability, why implement a userspace daemon that is required to sync with the kernel when kernel space modules could be written to directly manipulate the routing tables themselves?
Why write X windows when you could integrate them in kernel (like winNT do)?
a) portability
b) crash-proofness
c) bird is swappable
d) bird can use libc
e) bird is preemptibly-scheduled. If it loops, nothing bad happens.
You are true. But if you build HW routers based on linux, the kernel crash or the bird crash are the same problems. Today's BGP adds about 100 000 items into routing table. It uses a lot of memory and I'm not sure, that the transfer is so efficient.
Pavel
Kind regards Feela
Hello!
You are true. But if you build HW routers based on linux, the kernel crash or the bird crash are the same problems.
Not exactly the same -- the userspace crashes are at least automatically recoverable.
Today's BGP adds about 100 000 items into routing table. It uses a lot of memory and I'm not sure, that the transfer is so efficient.
It should be -- last time I've tested it (one year ago), I was feeding my kernel with full BGP tables from the default-free zone and there were no performance problems. Have a nice fortnight -- Martin `MJ' Mares <mj@ucw.cz> http://atrey.karlin.mff.cuni.cz/~mj/ Faculty of Math and Physics, Charles University, Prague, Czech Rep., Earth Disc space, the final frontier!
participants (3)
-
Martin Mares -
Ondrej Filip -
Pavel Machek