Windows 2000 Advantage - Tech Edge - Technology tips for IT executives

Boost your multiprocessing power

As users demand higher performance from their applications and computers, your organization will require increased parallel-computing capabilities.

In the simplest case, outfitting individual machines with dual processors will do the trick, offering a small-to-moderate performance increase to many users as they perform day-to-day tasks. For users running Windows NT, which supports multiple processors, one processor can be allocated to run the main application while the second processor is allocated to perform operating system tasks.

Adding second processors to existing network servers will result in similar performance improvements. But to get to the best performance out of a multiprocessor configuration, primary software applications must be carefully designed and implemented in advance to take advantage of the multiprocessor hardware.

The basics: Breaking down applications

An application that most effectively takes advantage of multiple processors must be designed so that its different parts can run on different processors. A crude approach would be to break the application down into several small executable programs, allowing the operating system to run the different executables on different processors. The best way to design such an application, however, would be to break it down into several "threads" of execution. Each thread could then execute independent of the others. In this case, the program would have to be carefully designed in such a way that all its threads could run at the same time without interfering with each other.

Designing applications in this way has the advantage of improved resource use—primarily as a result of lower memory and CPU overhead— and results in more efficient code, and often faster execution. Windows NT is able to assign a different CPU to each thread, thereby allowing multithreaded applications to take advantage of multiprocessor machines, as well as single-processor machines in a more limited way. Single-threaded applications are not able to do this, and therefore do not benefit from a multiprocessor machine.

Developers writing multithreaded applications encounter several issues not found in single-threaded applications. For example, if two threads of execution need to update the same piece of global data at the same time, it is important that this update be synchronized to avoid data corruption.

Preparing for multithreaded application development

If you manage the development of a multithreaded application, it's important to ensure that your team has sufficient training and experience.

Here are some tips to ensure a smooth process:

Be sure to understand what parallel processing can and cannot do

Some applications aren't well-suited for parallel processing. In such cases, your overall performance improvement may be minimal. You may hope that doubling the number of processors will make your application run twice as fast, but a performance improvement of 80 to 90 percent is more likely. In some rare cases, doubling the number of processors will, in fact, result in the application running more than twice as fast. When this happens, it's often referred to as a "super-linear" performance improvement.

Carefully estimate the complexity of parallel applications

I've heard project managers say, "We don't do multithreaded applications, because the technology is too difficult for most developers to understand." If your team doesn't have multithreaded-development experience, it's up to you to determine whether the benefits of making your company's applications multithreaded outweigh the cost of ensuring that your developers have the appropriate training and experience.

Provide for adequate training

It's important to ensure that your entire development team has sufficient training in multithreaded development, but don't send the whole team to the same training course. Different team members will require different levels of training. Less experienced developers with a good understanding of the basic concepts behind multithreaded application development will be able to learn a great deal from more experienced developers. Don't expect a team of less experienced developers to return from a one-week training course and immediately be 100 percent adept at writing multithreaded applications. Some things are best learned from experience.

Make sure you have experienced architects on your team

Having trained your developers, remember that even your most experienced team members, while they may know your business inside out, still do not necessarily have hands-on experience developing large multithreaded applications. Some team members may promote the benefits of parallel computing because they've seen or heard various success stories; some may promote it because they see its potential and wish to learn more about it. You should keep in mind the fact that this technology is still relatively new to many; even those developers who are very interested in the technology may be inexperienced with it—which isn't to say they can't learn.

For larger multithreaded application projects, bring in experienced architects to work with key developers and help guide them through the design process. Experienced architects will be able to provide a robust, multithreaded design for your application and steer your team away from potential problem areas.

By ensuring that your applications make effective use of threads, you can begin to realize the benefits of multiprocessor machines.