Date: Tue, 11 Jan 2005 21:30:54 -0500 From: Chuck Swiger <cswiger@mac.com> To: "Timothy J. Luoma" <lists@tntluoma.com> Cc: freebsd-questions@freebsd.org Subject: Re: Hyperthreading hurts 5.3? Message-ID: <41E48BDE.7010301@mac.com> In-Reply-To: <9094-SnapperMsgD246FC56BE0A255B@68.243.126.247> References: <9094-SnapperMsgD246FC56BE0A255B@68.243.126.247>
next in thread | previous in thread | raw e-mail | index | archive | help
Timothy J. Luoma wrote: > summary: should I disable hypertheading in the BIOS when running 5.3? It would certainly be worth trying this and seeing whether running as a purely single-proc system performs better for you. It's not exactly as if HyperThreading evolved out of a sensible plan like "let's design a multi-core CPU intended for parallel execution, or something like a m56k DSP with VLIW", the situation is more like "Intel created the P4 such a monsterously long pipeline that breaks x86 instructions into tiny u-ops which require a lot of functional units to be available, only the CPU still can't schedule things to use all of the available units much of the time, anyway, so hey, maybe we could run another processing thread on 'em and hope the additional work it can do outweighs the additional CPU resource contention and the additional overhead of doing SMP..." [ I have a non-HT P4 (a 2.4MHz@400FSB Northwood) around, but I doubt I'd turn HT on with it even if it could. I'd rather use an AMD-64, or a G5, or even a recent P3 (Tualatin/Pentium-M) than another hyperthermal P4 spaceheater. ] Bah, I'm rambling, time to stop... :-) -- -Chuck
Want to link to this message? Use this URL: <https://mail-archive.FreeBSD.org/cgi/mid.cgi?41E48BDE.7010301>