Compaq 307560-001 intraNetWare Symmetric Multiprocessing - Page 5

ECG045/1097 INTEGRATION NOTE (cont.) 5... more than one processor and is asymmetric. One processor is dedicated to the I/OEngine, which responds to hardware events. The second processor is dedicated to the MSEngine which provides network and file services to clients. This design is asymmetric because only the I/OEngine handles interrupts. NetWare SFT III, like standard NetWare, is non-preemptive. Each NetWare Loadable Module (NLM) must yield control of system resources before another NLM can begin a task. NLM code must be written so that no single NLM controls the system for too long. In a preemptive environment, the operating system controls how long each process is allowed to run before handing control to a different one. Preemptive environments are more useful when servicing priority tasks because the operating system can preempt other tasks and does not have to wait until the NLM yields control. NOTE: NetWare SFT-III servers do not currently support SMP. INTRANET WARE SMP Novell features SMP functionality with intraNetWare/NetWare 4.11 SMP. The standard NetWare operating system still exists and runs strictly on the boot processor as though there were only a single processor available. The SMP functionality, called the NetWare SMP kernel, is an addition to the traditional NetWare architecture and runs on the boot processor and secondary processors. The SMP kernel design has been added to the NetWare OS architecture to allow tasks to be handled symmetrically and preemptively. The SMP kernel design includes an algorithm for scheduling multiple incoming tasks to the processors available in a given system. In the past, this algorithm was not required because new tasks were added to the queue and processed in sequence by the available processor. The SMP kernel is preemptive so that database applications can service priority tasks more efficiently. Applications that are written to take advantage of SMP, referred to as SMP aware applications, can run preemptively on an available processor in the system. Multi-threaded SMP aware applications gain performance from parallelism in the SMP environment. Oracle7 Server and Novell's GroupWise are examples of SMP aware applications. Two other NLMs are necessary to enable the SMP environment. These components are the Platform Support Module (PSM) and the MP driver. The MP driver activates the secondary processors (processors beyond the boot processor). The PSM is provided by the hardware vendor in order for the SMP kernel to communicate with the processors. The PSM that Compaq supplies for intranetWare/NetWare 4.11 SMP is CPQSMP.PSM. This hardware support provides the same functionality as any device driver. For example, a network interface card requires a device driver to communicate between the network card and the operating system. The PSM is the same type of essential communication layer between the OS and the symmetric multiprocessing NetWare Apps SMP Applications NetWare OS MP Driver SMP Kernel MP Driver MP Driver MP Driver PSM (CPQSMP.PSM)