Date: Thu, 2 Oct 2003 14:20:48 -0300 (ADT) From: "Marc G. Fournier" <scrappy@hub.org> To: Damian Gerow <damian@sentex.net> Cc: hardware@freebsd.org Subject: Re: Hyperthreading Kernel Configuration - 5.1 Message-ID: <20031002141921.K25730@ganymede.hub.org> In-Reply-To: <20031002170952.GF15256@sentex.net> References: <200310021105.10872.john@johnrshannon.com> <20031002170952.GF15256@sentex.net>
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On Thu, 2 Oct 2003, Damian Gerow wrote: > Thus spake John R. Shannon (john@johnrshannon.com) [02/10/03 13:05]: > > On a new computer, dmesg shows: > > > > CPU: Intel(R) Pentium(R) 4 CPU 2.80GHz (2793.01-MHz 686-class CPU) > > Origin = "GenuineIntel" Id = 0xf29 Stepping = 9 > > Features=0xbfebfbff<FPU,VME,DE,PSE,TSC,MSR,PAE,MCE,CX8,APIC,SEP,MTRR,PGE,MCA,CMOV,PAT,PSE36,CLFLUSH,DTS,ACPI,MMX,FXSR,SSE,SSE2,SS,HTT,TM,PBE> > > Hyperthreading: 2 logical CPUs > > acpi_cpu0: <CPU> port 0x530-0x537 on acpi0 > > acpi_cpu1: <CPU> port 0x530-0x537 on acpi0 > > > > Should options SMP and APIC_IO be enabled in kernel? > > In short: yes. And then you need to look at the machdep.* sysctl nobs, > there's one you need to enable in there (I've forgotten which one). > > But that leads me to a secondary question: is enabling HTT really worth the > time? I know that people have said that using HTT can actually make your > system slower -- is this an implementation issue, or did Intel really > release something that degrades performance? My understanding is that the speed improvements (or degradation) depend on the use of the machine ... for instance, I've heard that a high I/O server will be slower with HTT enabled, and, from my experience with one such, it is so ... I'm not sure what circumstances would show improvements though ...home | help
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