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Old 04-21-2010, 06:05 AM   #1
linuxunix
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uname output issue?


I just added PAE kernel packages on my OEL 5.5. And then could successully boot into PAE Kernel through GRUB.BUT when I issue command:

Code:
Linux ns3.findmenet.com 2.6.18-164.2.1.el5.028stab066.10PAE #1 SMP Sat Dec
12 13:11:57 MSK 2009 i686 i686 i386 GNU/Linux
[root@ns3 ~]#
It shows PAE but also shows SMP .How can i remove that?
 
Old 04-21-2010, 07:03 AM   #2
rylan76
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Why do you need / want to remove that?
 
Old 04-21-2010, 07:38 AM   #3
smoker
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SMP means Symmetric MultiProcessing

You must have a dual core processor or more than one processor on the system.

Most people want SMP, why don't you ?

http://en.wikipedia.org/wiki/Symmetric_multiprocessing
 
Old 04-21-2010, 09:39 AM   #4
linuxunix
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Just want to know if PAE and SMP co-exist?
I am new to this concept.Anyone who can explain me with:
1. When I installed by default it says: SMP
2. I added kernel-PAE and edited grub.conf, added entry for the same.
Now Booted to PAE but it still shows SMP.

Please clarify the difference.

Last edited by linuxunix; 04-21-2010 at 09:41 AM.
 
Old 04-21-2010, 10:21 AM   #5
smoker
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PAE is Physical Address Extension, which is nothing to do with SMP.

PAE was designed to allow the cpu to access more than 4GB of RAM. (on 32 bit systems - 64 bit can already access more than 4GB)
This means programs only need to worry about accessing normal memory space, because the PAE maps memory higher than 4GB into a 32 bit accessible addresses.

SMP is multiple CPU support.

Some distros include PAE by default these days, but you have got it anyway.
A benefit of PAE is that it supports the NX bit which is a security method to prevent malicious programming.

Editing grub wont change uname, because uname queries the kernel version.
Same as
Code:
rpm -q kernel
The SMP is because you have more than one physical cpu or cpu core .

If you really want to stop having the benefits of SMP, then you can edit the kernel parameters in grub.conf and put
Code:
nosmp
or

Code:
maxcpus=0
at the end of the line. Both of those will disable the smp code.

(allegedly - I haven't tried it because I have a dual quad core system, and why pay for extra cpu if you are going to disable them ?)

Last edited by smoker; 04-21-2010 at 10:34 AM.
 
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