----- Original Message ----- From: "Robert L. Cochran" <cochranb@speakeasy.net> To: <psyche-list@redhat.com> Sent: Monday, October 14, 2002 2:35 PM Subject: Re: Hyper Threaded Pentium 4 > I'm new to the CPU-level stuff and don't have much background in them. > So some of the terms are new for me. Let me get really basic: why would > you want multiple processors on a motherboard as opposed to a single > fast processor? I take it that the Xeon line is for multiple CPU > motherboards -- you don't just run one Xeon, am I right? What does it > mean, to be 'cpu cache bound'? Xeon and P4's waste a large number of clock cycles during "wait states", that is when it is idle, waiting for data to be read from the system memory which is far slower. I think hyperthreading has two sets of registers rather than one, allowing for execution of another task during these types of otherwise wasted CPU cycles. This can lead to greater efficiency in CPU usage, but only performance gains if applications are optimized to hyperthreading. In other cases you will actually lose performance. > > Do your comments also mean the Red Hat kernel won't need testing on the > new Hyper Threaded P4s? > I suspect that it will work if the new P4 HT, but without hardware we wont be sure until we as the community tests it. If it doens't work, you will have to wait for an errata kernel or build your own custom kernel. -- Psyche-list mailing list Psyche-list@redhat.com https://listman.redhat.com/mailman/listinfo/psyche-list
