Intel Pentium 640+ processor (LGA775) recognized as two prcessors?

victorh · 02-01-2006, 10:26 PM

Hi, this is something bizarre that happened to me.
I have bought recently a new PC, with the following processor:
Intel Pentium 4 Processor 640+ (LGA775)
Supporting Hyper-Threading Technology
3.20 GHz
800 MHz FSB
2 MB L2 Cache
Intel EM64T (supports 64-bit computing)
BUT, when I installed several Linuxes in it, they all recognized as if I have two processors, I installed Suse 10 (32-bit), Gentoo (64-bit) and Mandriva 2006 (32-bit). The three of them tell me that I have two processors, how could this be true?

I post you some commands (currently in SuSE), so you can help me understand what is going on:

Code:

victor@linux:/proc> cat cpuinfo
processor       : 0
vendor_id       : GenuineIntel
cpu family      : 15
model           : 4
model name      : Intel(R) Pentium(R) 4 CPU 3.20GHz
stepping        : 3
cpu MHz         : 3200.687
cache size      : 2048 KB
physical id     : 0
siblings        : 2
core id         : 0
cpu cores       : 1
fdiv_bug        : no
hlt_bug         : no
f00f_bug        : no
coma_bug        : no
fpu             : yes
fpu_exception   : yes
cpuid level     : 5
wp              : yes
flags           : 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 ht tm pbe nx lm pni monitor ds_cpl est cid cx16 xtpr
bogomips        : 6408.27

processor       : 1
vendor_id       : GenuineIntel
cpu family      : 15
model           : 4
model name      : Intel(R) Pentium(R) 4 CPU 3.20GHz
stepping        : 3
cpu MHz         : 3200.687
cache size      : 2048 KB
physical id     : 0
siblings        : 2
core id         : 0
cpu cores       : 1
fdiv_bug        : no
hlt_bug         : no
f00f_bug        : no
coma_bug        : no
fpu             : yes
fpu_exception   : yes
cpuid level     : 5
wp              : yes
flags           : 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 ht tm pbe nx lm pni monitor ds_cpl est cid cx16 xtpr
bogomips        : 6400.77

And this is some part of dmesg:

Code:

victor@linux:~> dmesg
Linux version 2.6.13-15.7-smp (geeko@buildhost) (gcc version 4.0.2 20050901 (prerelease) (SUSE Linux)) #1 SMP Tue Nov 29 14:32:29 UTC 2005
BIOS-provided physical RAM map:
 BIOS-e820: 0000000000000000 - 000000000009fc00 (usable)
 BIOS-e820: 000000000009fc00 - 00000000000a0000 (reserved)
 BIOS-e820: 00000000000e6000 - 0000000000100000 (reserved)
 BIOS-e820: 0000000000100000 - 000000001fe2f800 (usable)
 BIOS-e820: 000000001fe2f800 - 000000001fe3e8b3 (ACPI NVS)
 BIOS-e820: 000000001ff2f800 - 000000001ff30000 (ACPI NVS)
 BIOS-e820: 000000001ff30000 - 000000001ff40000 (ACPI data)
 BIOS-e820: 000000001ff40000 - 000000001fff0000 (ACPI NVS)
 BIOS-e820: 000000001fff0000 - 0000000020000000 (reserved)
 BIOS-e820: 00000000e0000000 - 00000000f0000000 (reserved)
 BIOS-e820: 00000000fed13000 - 00000000fed1a000 (reserved)
 BIOS-e820: 00000000fed1c000 - 00000000feda0000 (reserved)
0MB HIGHMEM available.
510MB LOWMEM available.
found SMP MP-table at 000ff780
On node 0 totalpages: 130607
  DMA zone: 4096 pages, LIFO batch:1
  Normal zone: 126511 pages, LIFO batch:31
  HighMem zone: 0 pages, LIFO batch:1
DMI 2.3 present.
Using APIC driver default
ACPI: RSDP (v000 ACPIAM                                ) @ 0x000f4ea0
ACPI: RSDT (v001 INTEL  D915PCY  0x20050429 MSFT 0x00000097) @ 0x1ff30000
ACPI: FADT (v002 INTEL  D915PCY  0x20050429 MSFT 0x00000097) @ 0x1ff30200
ACPI: MADT (v001 INTEL  D915PCY  0x20050429 MSFT 0x00000097) @ 0x1ff30390
ACPI: MCFG (v001 INTEL  D915PCY  0x20050429 MSFT 0x00000097) @ 0x1ff30400
ACPI: ASF! (v016 LEGEND I865PASF 0x00000001 INTL 0x02002026) @ 0x1ff35f90
ACPI: SSDT (v001 DpgPmm  Cpu1Ist 0x00000010 INTL 0x02002026) @ 0x1ff36030
ACPI: SSDT (v001 DpgPmm  Cpu2Ist 0x00000010 INTL 0x02002026) @ 0x1ff36440
ACPI: SSDT (v001 DpgPmm    CpuPm 0x00000010 INTL 0x02002026) @ 0x1ff36850
ACPI: TCPA (v001 INTEL  TBLOEMID 0x00000001 MSFT 0x00000097) @ 0x1ff36990
ACPI: WDDT (v001 INTEL  OEMWDDT  0x00000001 INTL 0x02002026) @ 0x1ff369c2
ACPI: DSDT (v001 INTEL  D915PCY  0x00000001 INTL 0x02002026) @ 0x00000000
ACPI: PM-Timer IO Port: 0x408
ACPI: Local APIC address 0xfee00000
ACPI: LAPIC (acpi_id[0x01] lapic_id[0x00] enabled)
Processor #0 15:4 APIC version 20
ACPI: LAPIC (acpi_id[0x02] lapic_id[0x01] enabled)
Processor #1 15:4 APIC version 20
ACPI: LAPIC_NMI (acpi_id[0x01] dfl dfl lint[0x1])
ACPI: LAPIC_NMI (acpi_id[0x02] dfl dfl lint[0x1])
ACPI: IOAPIC (id[0x02] address[0xfec00000] gsi_base[0])
IOAPIC[0]: apic_id 2, version 32, address 0xfec00000, GSI 0-23
ACPI: INT_SRC_OVR (bus 0 bus_irq 0 global_irq 2 dfl dfl)
ACPI: INT_SRC_OVR (bus 0 bus_irq 9 global_irq 9 high level)
ACPI: IRQ0 used by override.
ACPI: IRQ2 used by override.
ACPI: IRQ9 used by override.
Enabling APIC mode:  Flat.  Using 1 I/O APICs
Using ACPI (MADT) for SMP configuration information
Allocating PCI resources starting at 20000000 (gap: 20000000:c0000000)
Built 1 zonelists
Kernel command line: root=/dev/hdb2 vga=0x31a selinux=0    resume=/dev/hdb1  splash=silent
bootsplash: silent mode.
Initializing CPU#0
PID hash table entries: 2048 (order: 11, 32768 bytes)
Detected 3200.687 MHz processor.
Using pmtmr for high-res timesource
Console: colour dummy device 80x25
Dentry cache hash table entries: 65536 (order: 6, 262144 bytes)
Inode-cache hash table entries: 32768 (order: 5, 131072 bytes)
Memory: 510740k/522428k available (2330k kernel code, 11092k reserved, 745k data, 252k init, 0k highmem)
Checking if this processor honours the WP bit even in supervisor mode... Ok.
Calibrating delay using timer specific routine.. 6408.27 BogoMIPS (lpj=12816551)
Security Framework v1.0.0 initialized
SELinux:  Disabled at boot.
Mount-cache hash table entries: 512
CPU: After generic identify, caps: bfebfbff 20100000 00000000 00000000 0000649d 00000000 00000000
CPU: After vendor identify, caps: bfebfbff 20100000 00000000 00000000 0000649d 00000000 00000000
monitor/mwait feature present.
using mwait in idle threads.
CPU: Trace cache: 12K uops, L1 D cache: 16K
CPU: L2 cache: 2048K
CPU: Physical Processor ID: 0
CPU: After all inits, caps: bfebfbff 20100000 00000000 00000080 0000649d 00000000 00000000
Intel machine check architecture supported.
Intel machine check reporting enabled on CPU#0.
CPU0: Intel P4/Xeon Extended MCE MSRs (24) available
CPU0: Thermal monitoring enabled
mtrr: v2.0 (20020519)
Enabling fast FPU save and restore... done.
Enabling unmasked SIMD FPU exception support... done.
Checking 'hlt' instruction... OK.
checking if image is initramfs... it is
Freeing initrd memory: 1753k freed
ACPI: Looking for DSDT in initrd... not found!
 not found!
CPU0: Intel(R) Pentium(R) 4 CPU 3.20GHz stepping 03
Booting processor 1/1 eip 3000
Initializing CPU#1
Calibrating delay using timer specific routine.. 6400.77 BogoMIPS (lpj=12801543)
CPU: After generic identify, caps: bfebfbff 20100000 00000000 00000000 0000649d 00000000 00000000
CPU: After vendor identify, caps: bfebfbff 20100000 00000000 00000000 0000649d 00000000 00000000
monitor/mwait feature present.
CPU: Trace cache: 12K uops, L1 D cache: 16K
CPU: L2 cache: 2048K
CPU: Physical Processor ID: 0
CPU: After all inits, caps: bfebfbff 20100000 00000000 00000080 0000649d 00000000 00000000
Intel machine check architecture supported.
Intel machine check reporting enabled on CPU#1.
CPU1: Intel P4/Xeon Extended MCE MSRs (24) available
CPU1: Thermal monitoring enabled
CPU1: Intel(R) Pentium(R) 4 CPU 3.20GHz stepping 03
Total of 2 processors activated (12809.04 BogoMIPS).
ENABLING IO-APIC IRQs
..TIMER: vector=0x31 pin1=2 pin2=-1
checking TSC synchronization across 2 CPUs: passed.
Brought up 2 CPUs
........

I'm pretty sure that I have only one processor

. But why it is recognized as two?
This is quite strange, but it had not caused any other bizarre behaior of the PC it works fine. Just wondering, do somebody had a clue?

WhatsHisName · 02-02-2006, 01:13 AM

What you are observing is normal for a hyperthread pentium.

hyperthread = smp

victorh · 02-02-2006, 02:37 PM

Thanks WhatsHisName, now I know that I'm using a Linux kernel with hyperthreading available.
I was doing some googling, and didn't found much information about the use of Hyperthreading in Linux, specially if there are programs that use this technology (besides the kernel) and how could I take advantage of this technology?.
Do you know some other source of information on this topic?.
Given the fact that I own a processor with this technology, I'd like to use it to its full capacity.

lestoil · 02-02-2006, 04:36 PM

Start at Intel web site for your cpu. They will have hyperthreading explanation. I am sure several xp programs claim to use the hyperthreading. I have hyperthreading cpu too and haven't noticed much difference for my usual activities under xp or linux.Enjoy!

WhatsHisName · 02-02-2006, 04:59 PM

Questions about the use of threading in linux applications have started many heated debates, such as the one here: http://www.linuxquestions.org/questi...d.php?t=389403

umbepo · 04-22-2006, 03:17 AM

a question... i tried to install fedora core 4, (i have the same processor as victorh, exactly the same) i have an issue with the partition.. might it be because i downloaded the 32-bit fedora? thanks!

cs-cam · 04-22-2006, 04:17 AM

umbepo: Nope, 32bit stuff will run fine on all consumer 64bit processors. Probably should have started a new thread though.