Hi,
I've looked for a mailing list for OpenBGPD but come up empty. If there's
a better place to report this, please let me know.
I'm using OpenBGPD as a fairly large route collector. In total, about 75
neighbors announcing ~21 million prefixes. This is
openbgpd-4.9.20110612_1 running on FreeBSD (latest from ports collection).
# bgpctl show ip bgp memory
RDE memory statistics
456227 IPv4 unicast network entries using 17.4M of memory
912454 rib entries using 55.7M of memory
42436670 prefix entries using 2.5G of memory
3270891 BGP path attribute entries using 374M of memory
102926 BGP AS-PATH attribute entries using 4.6M of memory,
and holding 3270891 references
10722 BGP attributes entries using 419K of memory
and holding 9317049 references
10721 BGP attributes using 123K of memory
RIB using 3.0G of memory
I find that during start-up, the CPU of the "route decision engine"
process is steady between 90-100%. During this time, "bgpctl" hangs.
This lasts at least 45 minutes.
I believe most of the CPU is spent in "path_lookup()", traversing the
linked list in pathtable.path_hashtbl[]. I think a suitable fix would be
to increase the hash table sizes (rde.c:152):
u_int32_t peerhashsize = 64;
u_int32_t pathhashsize = 1024;
u_int32_t attrhashsize = 512;
u_int32_t nexthophashsize = 64;
It seems like it would also make sense to have these variables exposed to
the user somehow. Maybe optional config knobs like this:
hashsize peer 64
hashsize path 1024
hashsize attr 512
hashsize nexthop 64
In addition, we could use the hash as an easy check for inequality. This
would optimize the check for path_compare() where we only care about
equality. There are a couple cases like this:
- if (peer == asp->peer && path_compare(aspath, asp) == 0)
+ if (peer == asp->peer && path_equal(aspath, asp))
int path_equal(struct rde_aspath *a, struct rde_aspath *b)
{
if (a->hash != b->hash)
return 0;
else
return path_compare(a, b) == 0;
}
This change should probably be coupled with a better hash calculation.
Finally, I was surprised to see double the prefix entry count. I carry
21M routes (add up the last column of "bgpctl show"). Yet, the output
above shows 42M "prefix entries". I do not modify the prefixes at all; my
rule set contains only "deny to any; allow from any".
Thoughts?
Thanks for OpenBGPD!
--
kevin brintnall
Network Engineer, CenturyLink
