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Old 03-10-2011, 09:01 AM   #1
hanamilani
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missing memory on opensuse


Hi,

I work on opensuse 11.2 32 bit on my core 2 quad. Although I have 8GiB ram, in the system monitor I see 3.5GiB!!!! I really need 8GiB ram, please let me know why a part of the ram is missing?

Best Rgrds,
 
Old 03-10-2011, 09:05 AM   #2
johnsfine
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1) Make sure you have a PAE kernel. A non PAE 32 bit kernel is limited to 3 and a fraction GB of ram. I'm not certain what the PAE kernel is called in opensuse; Only some distributions give it an obvious name.

Most distributions let you upgrade to a PAE kernel through the package manager. So that should be very easy once you know the name of the package you need. Unlike most package installations, this one doesn't have any effect until the next reboot.

2) You might also want to check whether your BIOS and motherboard are really enabling ram beyond 3.5GB for use by the OS. They might detect and report that ram, but not allow the OS to use it.

See my post at
http://www.linuxquestions.org/questi...0/#post3865990

3) You might consider switching to 64 bit. That is much harder than switching the kernel to PAE and will not enable any part of your 8GB of ram that PAE won't enable (if it is a BIOS or motherboard issue, 64 bit will still be limited to 3.5GB). So probably it won't be worth the trouble of switching to 64 bit. But individual needs vary.

Last edited by johnsfine; 03-10-2011 at 09:17 AM.
 
Old 03-10-2011, 09:22 AM   #3
hanamilani
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Quote:
Originally Posted by johnsfine View Post
1) Make sure you have a PAE kernel. A non PAE 32 bit kernel is limited to 3 and a fraction GB of ram. I'm not certain what the PAE kernel is called in opensuse; Only some distributions give it an obvious name.

Most distributions let you upgrade to a PAE kernel through the package manager. So that should be very easy once you know the name of the package you need. Unlike most package installations, this one doesn't have any effect until the next reboot.

2) You might also want to check whether your BIOS and motherboard are really enabling ram beyond 3.5GB for use by the OS. They might detect and report that ram, but not allow the OS to use it.

See my post at
http://www.linuxquestions.org/questi...0/#post3865990

3) You might consider switching to 64 bit. That is much harder than switching the kernel to PAE and will not enable any part of your 8GB of ram that PAE won't enable (if it is a BIOS or motherboard issue, 64 bit will still be limited to 3.5GB). So probably it won't be worth the trouble of switching to 64 bit. But individual needs vary.
I read your thread thank u.

here is some results:

linux-gh1l:~/Desktop # uname -a
Linux linux-gh1l 2.6.31.5-0.1-default #1 SMP 2009-10-26 15:49:03 +0100 i686 i686 i386 GNU/Linux

linux-gh1l:~/Desktop # dmesg | grep e820:
[ 0.000000] BIOS-e820: 0000000000000000 - 000000000009f800 (usable)
[ 0.000000] BIOS-e820: 000000000009f800 - 00000000000a0000 (reserved)
[ 0.000000] BIOS-e820: 00000000000f0000 - 0000000000100000 (reserved)
[ 0.000000] BIOS-e820: 0000000000100000 - 00000000dfee0000 (usable)
[ 0.000000] BIOS-e820: 00000000dfee0000 - 00000000dfee3000 (ACPI NVS)
[ 0.000000] BIOS-e820: 00000000dfee3000 - 00000000dfef0000 (ACPI data)
[ 0.000000] BIOS-e820: 00000000dfef0000 - 00000000dff00000 (reserved)
[ 0.000000] BIOS-e820: 00000000f0000000 - 00000000f4000000 (reserved)
[ 0.000000] BIOS-e820: 00000000fec00000 - 0000000100000000 (reserved)
[ 0.000000] BIOS-e820: 0000000100000000 - 0000000220000000 (usable)

I am going to find PAE kernel. But what if my problem arise from the motherboard bios?
 
Old 03-10-2011, 12:18 PM   #4
johnsfine
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Quote:
Originally Posted by hanamilani View Post
[ 0.000000] BIOS-e820: 0000000100000000 - 0000000220000000 (usable)
That means there is exactly 4.5GiB of ram that a PAE or 64 bit kernel can use above the amount a non PAE 32 bit kernel can use.

There is never a full 8GiB available, so I'll assume your 3.5GiB was a slight over estimate. So you have near 3.5GiB usable without PAE plus an additional 4.5GiB with PAE should be near 8GiB.

Quote:
I am going to find PAE kernel. But what if my problem arise from the motherboard bios?
No need to worry. You just demonstrated that the BIOS and motherboard are not a problem.

BTW:
Quote:
Originally Posted by hanamilani View Post
[ 0.000000] BIOS-e820: 000000000009f800 -
...
[ 0.000000] BIOS-e820: 00000000dfee0000 -
The info around that 9f8 means 386Kib is missing near the beginning of the first 3.5GiB and the info around the dfee means 1152KiB is missing at the end of the first 3.5GiB. No other chunks are missing. The later 4.5GiB is unusable without PAE, but with PAE it is complete (no missing chunks). That is a remarkably tiny amount to be missing at the level that the BIOS provides ram to the OS. I don't think I've ever seen a ram map in which that much of the original 8GiB is usable.

Last edited by johnsfine; 03-10-2011 at 12:38 PM.
 
  


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