By Salvatore Salamone
October 15, 2003 | When one overloaded worker is swamped, hand off some of the work to someone else. That’s the simple idea behind a technology that promises to improve the performance of many life science applications.
The technology, implemented in what’s called a TCP Offload Engine, is being built into a new wave of network adapter cards. These TOE cards, as the name implies, offload the TCP communications tasks -- a big part of network transactions -- from a server’s central processing unit.
“TOE cards accelerate performance by performing the TCP transactions in hardware, as opposed to in software on the host CPU,” says Nancy Marrone-Hurley, an analyst with the consultancy Enterprise Storage Group. These TCP tasks include such things as data flow control and interrupt processing. Offloading these operations to a dedicated device frees up the server’s CPU so it can do more of its real work. Users get faster response from their applications, and servers can handle more simultaneous chores, such as queries to a database.
Several vendors, including Alacritech, Adaptec, Intel, and Q-Logic, have either recently announced TOE cards or said they will soon bring them to market. Prices will probably run slightly higher than a premium network card.
The range of applications that can be improved with a TOE card cuts across the gamut of life science applications and includes high-performance storage systems that use TCP/IP, computational clusters, and many database applications. “Any application that requires a large number of [input/output] transactions will benefit from TOE,” Marrone-Hurley says.
The Center for Biomolecular Science and Engineering at the University of California at Santa Cruz is trying out a TOE card from Adaptec (called a TOE NAC, for network accelerator card) to support its research efforts. “The TCP/IP offload solution has substantially improved the efficiency of our high-performance, networked systems,” says Ann Pace, assistant director of the center. “The TOE NAC is enabling our UCSC genome research team to perform more tests, faster -- in some cases doubling the number of jobs completed and substantially accelerating our research efforts.”
Who Needs It?
But does everyone need a TOE card? Probably.
Some network experts estimate that it takes 100 percent of a 1GHz CPU’s total processing power to deal with TCP tasks when a 1Gbps (gigabit per second) network connection between devices is completely saturated. No matter what the transmission rate, a significant portion of a server’s CPU capacity is being used for simple communications tasks.
One common situation where a TOE might help is in distributed computations, such as a BLAST run, on a cluster. Typically, one or more storage servers are connected to the multiple nodes doing the actual BLAST computations. The storage servers provide the data to the nodes for use in calculations. Installing a TOE in a storage system enables the system to handle more simultaneous requests for data without crashing.
TOE technology might also help performance of an application server -- such as a database or Web server handling many simultaneous requests for data. A TOE could handle each request more efficiently, so users get their data faster.
But, as is often the case with new technology, IT managers usually have a difficult time making a business case for it because metrics to determine return on investment are hard to come by.
In general, in applications where network message sizes are small and server bandwidth is modest, a traditional network adapter card would likely do the trick. But when the average network message size is large or bandwidth to a server is high (or both), a TOE would in many cases improve the performance of the application driving this traffic load.
Alacritech has developed software to help managers determine if TOE technology would be suitable for their networks. The tool for Windows-based servers, called the TOE Analyzer, measures network message size, network throughput, and server CPU usage. This information is used to determine if, according to Alacritech’s analysis, a TOE would improve server efficiency. (The TOE Analyzer can be downloaded for free from Alacritech’s Web site.)