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

[Ben Greear]

I have completed the first pass at my attempt to speed up
FEA's handling of interfaces.

Basically, I removed live_config entirely, using pulled_config
in it's place.  For pulled_config, I only pull info about configured
interfaces, and for the observer, I ignore anything not in the
configured interfaces.  Interfaces are added to the various iftrees
when they are configured by the user.

In doing this, I hacked on a bunch of the xrl handler classes.
Mostly cosmetic, but it makes the patch quite large.  I tried to
remove or minimize direct access to the ifconfig's iftree objects,
but some seem necessary and remain.

The patch also still has a lot of debugging code in it.

But, it does appear to work.

I tested my 30-node scenario with ~600 interfaces (about 10-15 of them
associated with each xorp instance, and others not in any xorp).

With my patch, the load still goes to around 30 when I'm heavily modifying
interfaces in the xorps, but the time to make a xorpsh commit was a max of
about 6 seconds and the system was generally responsive.

fea also starts up quicker since it doesn't have to read all the interfaces
in on startup.

Without this latest addition, the system load went to 30, and xorpsh
commits were taking 90+ seconds.

So, it's definitely a winner for xorp on linux in my scenario.  It's
likely that if netlink is not used, or if there are few interfaces, or
if there are lots of interfaces and xorp is using all of them, then there
will NOT be a lot of gain from my patch (maybe even slightly worse performance
since I'm not batch-reading all interfaces with netlink now.)

Its also likely I broke the compile on some systems, as some of the netlink
code was still using live_config(), but evidently was #ifdef'd out on Linux
since it compiled fine for me.

Systems that don't use netlink shouldn't be affected much either way, I think,
but I've no way to really test them.

The patch is too big for the mailing list, but can be downloaded
from here:

http://www.candelatech.com/oss/fea_iftree.patch

Comments welcome.  If there is something I can do or change to give this more
of a chance of being accepted, please let me know.

Thanks,
Ben

-- 
Ben Greear <greearb at candelatech.com>
Candela Technologies Inc  http://www.candelatech.com