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#1 2008-04-20 13:04:27

DeltaXFX
Member
From: USA
Registered: 2006-08-01
Posts: 74

[SOLVED] Only seeing 4 out of 8 cores (2x Quad Core)

Hello all,

I just got some new toys today. A server with 2 E5410's. 2 quad core 2.33GHz Xeons. Great fun. Now I have installed Arch64 on it. The problem is I can only see 4 cores, not 8. The BIOS shows 2 processors detected and 8 logical processors detected.
cat /proc/cpuinfo shows:

processor    : 0
vendor_id    : GenuineIntel
cpu family    : 6
model        : 23
model name    : Intel(R) Xeon(R) CPU           E5410  @ 2.33GHz
stepping    : 6
cpu MHz        : 2333.416
cache size    : 6144 KB
physical id    : 0
siblings    : 2
core id        : 0
cpu cores    : 2
fpu        : yes
fpu_exception    : yes
cpuid level    : 10
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 syscall nx lm constant_tsc arch_perfmon pebs bts rep_good pni monitor ds_cpl vmx est tm2 ssse3 cx16 xtpr dca sse4_1 lahf_lm
bogomips    : 4671.73
clflush size    : 64
cache_alignment    : 64
address sizes    : 38 bits physical, 48 bits virtual
power management:

processor    : 1
vendor_id    : GenuineIntel
cpu family    : 6
model        : 23
model name    : Intel(R) Xeon(R) CPU           E5410  @ 2.33GHz
stepping    : 6
cpu MHz        : 2333.416
cache size    : 6144 KB
physical id    : 1
siblings    : 2
core id        : 0
cpu cores    : 2
fpu        : yes
fpu_exception    : yes
cpuid level    : 10
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 syscall nx lm constant_tsc arch_perfmon pebs bts rep_good pni monitor ds_cpl vmx est tm2 ssse3 cx16 xtpr dca sse4_1 lahf_lm
bogomips    : 4668.31
clflush size    : 64
cache_alignment    : 64
address sizes    : 38 bits physical, 48 bits virtual
power management:

processor    : 2
vendor_id    : GenuineIntel
cpu family    : 6
model        : 23
model name    : Intel(R) Xeon(R) CPU           E5410  @ 2.33GHz
stepping    : 6
cpu MHz        : 2333.416
cache size    : 6144 KB
physical id    : 0
siblings    : 2
core id        : 1
cpu cores    : 2
fpu        : yes
fpu_exception    : yes
cpuid level    : 10
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 syscall nx lm constant_tsc arch_perfmon pebs bts rep_good pni monitor ds_cpl vmx est tm2 ssse3 cx16 xtpr dca sse4_1 lahf_lm
bogomips    : 4668.30
clflush size    : 64
cache_alignment    : 64
address sizes    : 38 bits physical, 48 bits virtual
power management:

processor    : 3
vendor_id    : GenuineIntel
cpu family    : 6
model        : 23
model name    : Intel(R) Xeon(R) CPU           E5410  @ 2.33GHz
stepping    : 6
cpu MHz        : 2333.416
cache size    : 6144 KB
physical id    : 1
siblings    : 2
core id        : 1
cpu cores    : 2
fpu        : yes
fpu_exception    : yes
cpuid level    : 10
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 syscall nx lm constant_tsc arch_perfmon pebs bts rep_good pni monitor ds_cpl vmx est tm2 ssse3 cx16 xtpr dca sse4_1 lahf_lm
bogomips    : 4668.31
clflush size    : 64
cache_alignment    : 64
address sizes    : 38 bits physical, 48 bits virtual
power management:

Am I missing something?
Current kernel is 2.6.24.4-1
Will I need to compile the kernel myself with some different options? And if so, what options would those be?

Thanks in advance!

Last edited by DeltaXFX (2008-08-04 17:33:19)


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#2 2008-04-20 13:33:49

.:B:.
Forum Fellow
Registered: 2006-11-26
Posts: 5,819

Re: [SOLVED] Only seeing 4 out of 8 cores (2x Quad Core)

Check your kernel config to see how many CPUs are supported (quadcore counts as 4 CPUs).


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#3 2008-04-20 13:55:47

brain0
Developer
From: Aachen - Germany
Registered: 2005-01-03
Posts: 1,382

Re: [SOLVED] Only seeing 4 out of 8 cores (2x Quad Core)

Our kernel configuration only allows four CPUs. Nobody ever requested more than that (at least there were no feature requests on the bugtracker).

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#4 2008-04-20 19:51:33

tth
Member
Registered: 2006-05-21
Posts: 12

Re: [SOLVED] Only seeing 4 out of 8 cores (2x Quad Core)

Are there any good reasons for not allowing more?  I don't think so.  Just increase the limit smile

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#5 2008-04-20 20:04:32

brain0
Developer
From: Aachen - Germany
Registered: 2005-01-03
Posts: 1,382

Re: [SOLVED] Only seeing 4 out of 8 cores (2x Quad Core)

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#6 2008-04-21 05:43:32

DeltaXFX
Member
From: USA
Registered: 2006-08-01
Posts: 74

Re: [SOLVED] Only seeing 4 out of 8 cores (2x Quad Core)

I think I can spare the extra 32K to make use of the other 4 cores.


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#7 2008-04-21 07:51:24

brain0
Developer
From: Aachen - Germany
Registered: 2005-01-03
Posts: 1,382

Re: [SOLVED] Only seeing 4 out of 8 cores (2x Quad Core)

DeltaXFX wrote:

I think I can spare the extra 32K to make use of the other 4 cores.

I think everyone else can, too. The question is, should we increase to 8 cores or directly go with 16? Anyone using Arch on a 16 core machine?

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#8 2008-04-21 10:12:26

DeltaXFX
Member
From: USA
Registered: 2006-08-01
Posts: 74

Re: [SOLVED] Only seeing 4 out of 8 cores (2x Quad Core)

I think it makes sense to up to 16 cores/processors. It is a very small increase in the size of the kernel. If anyone needs to save the 96K (going from 4 to 16 cores... is that right?) for some special project they are working on, most likely they are compiling a kernel specific to their application anyways. I don't think a normal user would be negatively affected by this.


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#9 2008-04-21 14:42:54

Noneus
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From: Munich
Registered: 2006-09-26
Posts: 118
Website

Re: [SOLVED] Only seeing 4 out of 8 cores (2x Quad Core)

With the upcoming new Intels with Hyperthreading there will be 16 core machines.

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#10 2008-04-22 03:03:03

wreck
Member
Registered: 2008-03-22
Posts: 18

Re: [SOLVED] Only seeing 4 out of 8 cores (2x Quad Core)

Noneus wrote:

With the upcoming new Intels with Hyperthreading there will be 16 core machines.

Indeed.  Enabling the extra cores now will negate future Nehalem compatibility issues.

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#11 2008-04-26 22:11:47

DeltaXFX
Member
From: USA
Registered: 2006-08-01
Posts: 74

Re: [SOLVED] Only seeing 4 out of 8 cores (2x Quad Core)

So should I submit a bug report/feature request for this? Or is there already a plan in the works?


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#12 2008-04-27 00:02:13

skottish
Forum Fellow
From: Here
Registered: 2006-06-16
Posts: 7,942

Re: [SOLVED] Only seeing 4 out of 8 cores (2x Quad Core)

DeltaXFX wrote:

So should I submit a bug report/feature request for this? Or is there already a plan in the works?

They're already talking about this:

http://archlinux.org/pipermail/arch-dev … 05872.html

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#13 2008-04-27 00:09:21

DeltaXFX
Member
From: USA
Registered: 2006-08-01
Posts: 74

Re: [SOLVED] Only seeing 4 out of 8 cores (2x Quad Core)

I saw that. But the last message was a week ago and it doesn't really sound like anything was decided for sure. Everyone seems up for the idea but it didn't sound like anything was finalized.


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#14 2008-08-04 15:19:24

entropic_existence
Member
Registered: 2008-05-20
Posts: 14

Re: [SOLVED] Only seeing 4 out of 8 cores (2x Quad Core)

I know this is an old thread. Does anyone know if this is fixed yet/resolved or if there is any way for me to resolve it? I just installed Arch on a new workstation I have at the lab and we desperately need all 8 cores (2 quad core CPUs) running otherwise half of our investment is sitting around wasted.

Should I compile my own kernel?

Advice is appreciated.

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#15 2008-08-04 16:13:26

DeltaXFX
Member
From: USA
Registered: 2006-08-01
Posts: 74

Re: [SOLVED] Only seeing 4 out of 8 cores (2x Quad Core)

I got it working and decided to wait it out until Arch officially supports 16 cores before I update the kernel again. These are the steps if I remember correctly...
Get the current kernel26 at http://archlinux.org/packages/core/x86_64/kernel26/
(you need to go to "view svn entries")
Download everything in there...
PKGBUILD
config
config.x86_64
kernel26.install
kernel26.preset

In "config" find the line "CONFIG_NR_CPUS" change it from "4" to "8" or whatever you want
"CONFIG_SPLIT_PTLOCK_CPUS" should also be changed to "8" if it isn't already

In "config.x86_64" look for the same two lines and make the appropriate changes.

Build and install the package as you normally would.
Restart, then cat /proc/cpuinfo should show a wonderfully long list of CPUs smile


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#16 2008-08-04 16:19:10

skottish
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From: Here
Registered: 2006-06-16
Posts: 7,942

Re: [SOLVED] Only seeing 4 out of 8 cores (2x Quad Core)

Has anyone tried the current kernel is testing for more processors support? I can't remember if it's the current one or the next one that this will be compiled into.

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#17 2008-08-04 16:23:26

DeltaXFX
Member
From: USA
Registered: 2006-08-01
Posts: 74

Re: [SOLVED] Only seeing 4 out of 8 cores (2x Quad Core)

It looks like the kernel in testing supports 16 cores. entropic_existence, you may want to just try the testing kernel.


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#18 2008-08-04 16:37:41

entropic_existence
Member
Registered: 2008-05-20
Posts: 14

Re: [SOLVED] Only seeing 4 out of 8 cores (2x Quad Core)

Ok, I was just looking at getting 2.6.26 from kernel.org and compiling a custom kernel with support for 8 cores from that but I will check out the one from Testing first just to see if that works.

Thanks for the updates guys.

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#19 2008-08-04 17:08:06

entropic_existence
Member
Registered: 2008-05-20
Posts: 14

Re: [SOLVED] Only seeing 4 out of 8 cores (2x Quad Core)

If I want to try the kernel from the Testing repository and I would like to install it in parallel then I assume I need to do it through ABS and not just using pacman -S testing/kernel26? Is that correct?

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#20 2008-08-04 17:19:52

rooloo
Member
Registered: 2008-07-09
Posts: 218

Re: [SOLVED] Only seeing 4 out of 8 cores (2x Quad Core)

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#21 2008-08-04 17:23:23

entropic_existence
Member
Registered: 2008-05-20
Posts: 14

Re: [SOLVED] Only seeing 4 out of 8 cores (2x Quad Core)

Thank you,

I have those within my ABS tree. smile

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#22 2008-08-04 17:32:29

DeltaXFX
Member
From: USA
Registered: 2006-08-01
Posts: 74

Re: [SOLVED] Only seeing 4 out of 8 cores (2x Quad Core)

I just tried the latest kernel from testing (2.6.26-2), it does indeed support 16 CPU's. All 8 of mine are showing up correctly with it. I am going to mark this thread solved.


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#23 2008-08-04 17:35:40

entropic_existence
Member
Registered: 2008-05-20
Posts: 14

Re: [SOLVED] Only seeing 4 out of 8 cores (2x Quad Core)

Yup, looks fine. I did notice in the testing config and config.x86_64 that CONFIG_SPLIT_PTLOCK_CPUS is at 4 and not 8 or 16

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#24 2008-08-04 17:37:48

DeltaXFX
Member
From: USA
Registered: 2006-08-01
Posts: 74

Re: [SOLVED] Only seeing 4 out of 8 cores (2x Quad Core)

I changed that to 8 when I edited the config for 8 cores... don't know if it was the correct thing to do, but it worked. Maybe someone can clarify it?
The kernel in testing seems to be working fine so far the way it is configured from Arch, so I'll just not touch anything.


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#25 2008-08-04 19:50:02

iBertus
Member
From: Greenville, NC
Registered: 2004-11-04
Posts: 2,228

Re: [SOLVED] Only seeing 4 out of 8 cores (2x Quad Core)

I'm glad to see that the testing kernel supports >4 cores. I just noticed that only 4 of mine were detected when installing Arch on a new machine. I used to use a totally custom kernel (for years) but now I stick to the Arch vanilla ones, it's just easier and faster.

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