haproxy, ec2 and multi cores

[Dan O'Bryan]

I'm in the process of moving our core traffic from a local datacenter
to ec2, using haproxy for load balancing.

I am unable to get full usage of the 2 virtual cores.  Previewed the
full traffic load today and hit cpu limits immediately.  Initially,
with nbproc = 1, I see the first core is used at 100% utilization, the
second core remains completely idle.  Tried setting with nbproc = 2,
same result, the second core stays completely idle.  All
recommendations I've read indicate that nbproc=1 is the preferred
setting and that multiple cores should still get utilized, but not
having any luck.

After a lot of reading and tinkering, ended up with the following setup:
   EC2: m1.large instance type, 2 virtual cores, 7.5GB ram,
   OS: based on canonical amis, 2.6.27-23-xen #1 SMP Thu Apr 16
14:36:38 UTC 2009 x86_64 GNU/Linux.
   HAProxy 1.3.18 with http-ecv patch

Hitting peak CPU bottlenecks when session rate hits about 2500, avg 6k
per request.

Do you have any suggestions to increase usage of both cores to improve
my per-node capacity?

Dan