Robert Hanson wrote:
Are you saying that the standard stock CentOS 4 kernel does not recognize nor use or take advantage of HT on a stand alone Intel processor and motherboard? This is a 865PERL w/LAN I use for development and testing...
There are two "standard" kernels distributed with every Red Hat system (CentOS being clone of RHEL). One without SMP support, and one with SMP support. The reason is that SMP support adds additional overhead to the kernel (access to kernel structures must be locked, and so forth). Most people are running UP machines, and therefore benefit from running kernel that is optimized for UP machines.
If you install CentOS on UP machine, Anaconda (that's the installer) will install only "kernel" package (the kernel optimized for UP machines, no SMP support). If you install CentOS on SMP machine or on UP P4 HT machine, Anaconda will install both "kernel" and "kernel-smp" packages, and make SMP kernel default.
So, to answer you question. Yes. By default it will take advantage if you initally installed it on SMP machine. If you installed on UP machine, and later on moved disks to SMP machine, you need to manually add kernel-smp package (not a big deal, rather trivial to do).
BTW, do note that HT processor still has only single core. Some reports indicate that there's not much advantage of HT over non-HT processors (and consequently not much advantage of running SMP kernel on HT processor). Your "two virtuall" processors are still running on single core. The real thing (dual-core processors) is something Intel has announced to start shipping in near future. Up until now, dual cores were limited to RISC processors such as UltraSPARC and Alpha.