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Hyper-Threading Technology allows two series of instructions to run simultaneously and independently on a single Intel® HT-enabled processor. With Hyper-Threading Technology enabled, the system treats a physical processor as two ``logical'' processors. Each logical processor is allocated a thread on which to work, as well as a share of execution resources such as cache memories, execution units, and buses.
Hyper-Threading Technology can be used on an SCO OpenServer system that is equipped with an Intel Xeon or HT-enabled Intel Pentium® 4 processor and that also includes a chipset and a system BIOS with support for HT Technology.
A multi-core processor is a single physical processor that includes two or more ``cores'' and one or more logical processors per core. Each core acts as a discrete processor, complete with its own set of execution resources. A dual-core processor includes two cores, with one logical processor per core. A dual-core processor that also includes Hyper-Threading Technology provides two cores and two logical processors per core, allowing the execution of four simultaneous threads.
SCO OpenServer supports Intel Xeon and Intel Pentium 4 multi-core processors. SCO OpenServer's multi-core support also requires a chipset and a system BIOS that support HT Technology.
Note that most SCO OpenServer commands treat logical processors
as physical CPUs.
Depending on whether or not Hyper-Threading is enabled,
the view that commands provide of your system will be different.
For example:
Dual-processor system with Hyper-Threading disabled
# cpuonoff -c
CPU1: active
CPU2: active
# uname -X | grep NumCPU
NumCPU = 2
Dual-processor system with Hyper-Threading enabled
# cpuonoff -c
CPU1: active
CPU2: active
CPU3: active
CPU4: active
# uname -X | grep NumCPU
NumCPU = 4
When you use Hyper-Threading Technology with SCO OpenServer, you will most likely see system performance improvements. Depending on the workload applied to the system, however, it is possible you could see a decrease in performance. You will probably want to run some system benchmarks with Hyper-Threading enabled and disabled to determine which offers the optimal configuration for your system.
ENABLE_JT=Y
shutdown -i6 -g0 -y