Date: Tue, 06 Jan 2004 10:56:20 -0500 (EST) From: John Baldwin <jhb@FreeBSD.org> To: Harald Schmalzbauer <h@schmalzbauer.de> Cc: freebsd-current@FreeBSD.org Subject: Re: some HTT questions Message-ID: <XFMail.20040106105620.jhb@FreeBSD.org> In-Reply-To: <200401061630.41005@harrymail>
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On 06-Jan-2004 Harald Schmalzbauer wrote: > On Tuesday 06 January 2004 16:21, John Baldwin wrote: >> On 06-Jan-2004 Harald Schmalzbauer wrote: >> > Hi all, >> > >> > I'm currently working on my first P4 ever. >> > I'm planning a colo production machine with FreeBSD 5.2 (RC2 atm). >> > The info of dmesg about the CPU shows: >> > >> > CPU: Intel(R) Pentium(R) 4 CPU 2.40GHz (2394.13-MHz 686-class CPU) >> > Origin = "GenuineIntel" Id = 0xf27 Stepping = 7 >> > >> > Features=0xbfebfbff<FPU,VME,DE,PSE,TSC,MSR,PAE,MCE,CX8,APIC,SEP,MTRR,PGE, >> >MCA,CMOV,PAT,PSE36,CLFLUS H,DTS,ACPI,MMX,FXSR,SSE,SSE2,SS,HTT,TM,PBE> >> > >> > So I think this CPU should be HyperThreading capable which gets hardened >> > by those lines: >> > >> > acpi_cpu0: <CPU> on acpi0 >> > acpi_cpu1: <CPU> on acpi0 >> > >> > But the next line gives my an error about CPU1: >> > >> > device_probe_and_attach: acpi_cpu1 attach returned 6 >> > >> > This line shows up a second time between probing of sio and nxp0. >> > >> > Ny my guess was that HTT should be enabled in the BIOS but the BIOS has >> > no entry about HTT. >> > >> > How can I use HTT and are my assumptions correct? >> >> Your assumptions are not correct. :) If your CPU does support HTT, then >> the dmesg will include an extra line that says >> ' Hyperthreading: X logical cpus'. The HTT Feature just means that we >> can check to see if this CPU has more than one core. It might still > > The Feature=<HTT> doesn't mean it supports HTT but means we are allowed to > check if it supports HyperThreading??? Well that's total control. Yes, the feature bit just means that it supports the registers that list the number of CPUs. When we look at that register, it then says it has one logical CPU, effectively no HTT. :) -- John Baldwin <jhb@FreeBSD.org> <>< http://www.FreeBSD.org/~jhb/ "Power Users Use the Power to Serve!" - http://www.FreeBSD.org/
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