I know it's not exactly answering your question, but i tried squid with SMP (workers http://wiki.squid-cache.org/Features/SmpScale)
OS Debian Lenny Intel(R) Xeon(R) CPU E5405 (4 cores) Load: 350/400 requests by second Squid 3.1.12 can increase CPU utilization with more than 80/90 % - one core - Squid 3.2.0.8-20110615* never run beyond 40% by core - i use two workers - In heavy load the CPU is halved It's very interesting for me because i load balance (with hash metric) a pool of squid and when one crash another can take his load I can't test with more workers because the problem is that squid does not share the cache and i lose 10/15 % of HIT * For the moment workers seems broken after this version Sorry for my english ...
