Frankly the whole discussion of CNA CPU utilization reminds me of the FUD the Fibre Channel camp put out years ago about iSCSI. They claimed software iSCSI initiators would work the poor CPUs in your servers so couldn't get decent disk performance without specialized iSCSI HBAs and TOE cards. Well, in a series of tests in Network Computing's Labs we found that the Microsoft iSCSI initiator worked just fine and that machines running the partial TCP offload included with Broadcom's latest (as of 2003) LOM chips actually outperformed the available iSCSI HBAs. Note that well over 80 percent of iSCSI servers use software initiators from Microsoft or VMware. Most users of iSCSI HBAs prefer them for simplified boot from SAN.
While I haven't seen the data Tom referred to in his blog, I'm not really all that concerned that an Emulex CNA accessing a RAM disk over FCoE could drive CPU utilization to 80 percent. After all, that was for 512 byte sequential access and the Emulex outperformed the Qlogic in the test by three times. Yes that's an unacceptable CPU utilization, but it's also an unattainable performance level. If 100,000 4K IOPS took even 30 percent of the server's CPU I'd be more concerned. Because I expect to use a tenth of the 800,000 IOPS that generated the high CPU utilization, I expect the CNA to eat 8 percent of my CPU, which is an acceptable level.
Even more significantly, by the time FCoE goes mainstream in 2011-2012 Emulex will have had time to fix their drivers, and/or come out with a next-generation CNA. After all, VMware ESX 4.0 reduced CPU utilization almost 50% for iSCSI compared to 3.5. While faster CPUs solved the iSCSI CPU problem it won't be the solution for FCoE. That's because faster CPUs just mean more VMs per host; that is if you don't run out of memory first, as I usually do.
The current Fibre Channel networking market is a classic oligopoly. Each of the two market segments, switched and HBAs, has three vendors that together have over 90 percent market share. In the switch market Brocade is the dominant player, having absorbed several former competitors. Cisco is a strong number two, while Qlogic brings up the rear selling almost exclusively into the SME market. For HBAs, Qlogic is the leader with Emulex holding the number-two position and Brocade selling a few HBAs here and there.