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Date:      Thu, 13 Feb 2003 00:54:24 +0100
From:      Erik Trulsson <ertr1013@student.uu.se>
To:        Mike Hoskins <mike@adept.org>
Cc:        stable@freebsd.org
Subject:   Re: 4.7-stable & smp
Message-ID:  <20030212235424.GA80222@falcon.midgard.homeip.net>
In-Reply-To: <20030212153845.M29394-100000@fubar.adept.org>
References:  <20030212153845.M29394-100000@fubar.adept.org>

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On Wed, Feb 12, 2003 at 03:43:53PM -0800, Mike Hoskins wrote:
> 
> After building world from a cvsup on Feb 10 I see,
> 
> % dmesg
> <snip>
> SMP: AP CPU #2 Launched!
> SMP: AP CPU #1 Launched!
> SMP: AP CPU #3 Launched!
> 
> I don't recall seeing mention of "CPU #3" before.  (It is a 2 CPU box.)
> Is this actually something broken (seems to work just fine), or just
> semantics?  :)  It does say "2 logical CPUs":

It is not a bug, it is a feature. :-)
The magical word here is "Hyperthreading".  With Intel's latest P4 and
Xeon CPUs you can treat each physical CPU as two logical CPUs. 
Basic support for this was recently added to -stable. You are seeing
the results of this.

> 
> CPU: Intel(R) XEON(TM) CPU 2.00GHz (1989.47-MHz 686-class CPU)
>   Origin = "GenuineIntel"  Id = 0xf24  Stepping = 4
> Features=0x3febfbff<FPU,VME,DE,PSE,TSC,MSR,PAE,MCE,CX8,APIC,SEP,MTRR,PGE,MCA,C
> MOV,PAT,PSE36,CLFLUSH,DTS,ACPI,MMX,FXSR,SSE,SSE2,SS,HTT,TM>
>   Hyperthreading: 2 logical CPUs
> real memory  = 1073676288 (1048512K bytes)
> avail memory = 1041915904 (1017496K bytes)
> Changing APIC ID for IO APIC #0 from 0 to 4 on chip
> Changing APIC ID for IO APIC #1 from 0 to 5 on chip
> Changing APIC ID for IO APIC #2 from 0 to 6 on chip
> Programming 16 pins in IOAPIC #0
> IOAPIC #0 intpin 2 -> irq 0
> Programming 16 pins in IOAPIC #1
> Programming 16 pins in IOAPIC #2
> FreeBSD/SMP: Multiprocessor motherboard
>  cpu0 (BSP): apic id:  0, version: 0x00050014, at 0xfee00000
>  cpu1 (AP):  apic id:  1, version: 0x00050014, at 0xfee00000
>  cpu2 (AP):  apic id:  2, version: 0x00050014, at 0xfee00000
>  cpu3 (AP):  apic id:  3, version: 0x00050014, at 0xfee00000
>  io0 (APIC): apic id:  4, version: 0x000f0011, at 0xfec00000
>  io1 (APIC): apic id:  5, version: 0x000f0011, at 0xfec01000
>  io2 (APIC): apic id:  6, version: 0x000f0011, at 0xfec02000

-- 
<Insert your favourite quote here.>
Erik Trulsson
ertr1013@student.uu.se

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