[Xorp-hackers] FEA performance improvements: only 'pull' active interfaces.

Bruce M. Simpson bms at ICSI.Berkeley.EDU
Wed Mar 26 07:54:59 PDT 2008

Ben Greear wrote:
> Pavlin Radoslavov wrote:
>> The problem with this solution is that it will work only for Netlink
>> on Linux. The (majoriyty of the) other mechanisms for obtaining the
>> network interface information (getifaddrs(3), ioctl(2), syssctl(3),
>> etc) don't allow the granularity for asking only the information for
>> a specific interface.
> Yes, this may only be useful for my scenario where I'm using a small
> number of interfaces per xorp instance, with large numbers of total interfaces.
> Only linux can virtualize routing tables, as far as I know, so this performance
> gain is only really important on Linux.

Unfortunately as Pavlin points out getifaddrs() retrieves information 
for *all* interfaces configured in the system. It gets expensive for 
large N because it doesn't build a tree, it just uses a linked list.

FreeBSD is about to see some virtualization support in this area, so a 
cross platform solution needs to be carefully considered.


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