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xiaweitang
Apprentice
Joined: 26 Feb 2010
Posts: 152
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 Posted: Mon Mar 01, 2010 5:30 pm Post subject: [SOLVED]memory shown is less than what I actually have! |
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I just used the top command to show how much memory is the system using. Surprisingly, I found the total memory is significantly less than what I actually have in the machine. I have 512MB + 1GB, but "top" shows
| Code: | | Mem: 900472k total, 162988k used, 737484k free, 6924k buffers |
and
| Code: | cat /proc/meminfo
MemTotal: 900472 kB
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| Code: | cat /etc/fstab
# <fs> <mountpoint> <type> <opts> <dump/pass>
/dev/sda1 /boot ext2 defaults,noatime 1 2
/dev/sda2 none swap sw 0 0
/dev/sda3 / ext3 noatime 0 1
/dev/cdrom /mnt/cdrom auto noauto,user 0 0
shm /dev/shm tmpfs nodev,nosuid,noexec 0 0 |
Last edited by xiaweitang on Tue Mar 02, 2010 11:25 pm; edited 1 time in total |
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albright
Advocate
Joined: 16 Nov 2003
Posts: 2588
Location: Near Toronto
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| Posted: Mon Mar 01, 2010 6:30 pm Post subject: |
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you may need to enable high memory support in kernel
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bobspencer123
Guru
Joined: 19 Dec 2005
Posts: 544
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| Posted: Mon Mar 01, 2010 7:30 pm Post subject: |
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| albright wrote: | | you may need to enable high memory support in kernel |
you should also check that your bios is actually recognizing your inserted memory modules ... sometimes one of the sockets will die/break or the ordering can effect things. If you bios is showing the correct amount then it is most likely a kernel issue high memory support will solve (though if I remember off the top of my head correctly, high memory support is only supposed to be needed for 4Gig + ... but I might be wrong and it won't hurt to try).
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gsoe
Apprentice
Joined: 10 Dec 2006
Posts: 289
Location: Denmark
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| Posted: Mon Mar 01, 2010 9:38 pm Post subject: |
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There's also an intermediate setting:
| Code: | ───────────────────── High Memory Support ────────────────────────┐
( ) off
(X) 4GB
( ) 64GB |
| Code: | CONFIG_HIGHMEM4G:
│ Select this if you have a 32-bit processor and between 1 and 4
│ gigabytes of physical RAM.
│
│ Symbol: HIGHMEM4G [=y]
│ Prompt: 4GB
│ Defined at arch/x86/Kconfig:1045
│ Depends on: <choice> && !X86_NUMAQ
│ Location:
│ -> Processor type and features
│ -> High Memory Support (<choice> [=y]) |
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BonezTheGoon
Bodhisattva
Joined: 14 Jun 2002
Posts: 1408
Location: Albuquerque, NM -- birthplace of Microsoft and Gentoo
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| Posted: Mon Mar 01, 2010 11:12 pm Post subject: |
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| bobspencer123 wrote: | | you should also check that your bios is actually recognizing your inserted memory modules ... sometimes one of the sockets will die/break or the ordering can effect things. If you bios is showing the correct amount then it is most likely a kernel issue high memory support will solve (though if I remember off the top of my head correctly, high memory support is only supposed to be needed for 4Gig + ... but I might be wrong and it won't hurt to try). |
I agree. It's possible, for instance, that your machine supports dual-channel RAM and you have incorrectly inserted the 512MB DIMM as the second channel, instead of an extension of the maximum available in the single channel, which should never be done as dual-channel configuration is supposed to have matching pairs. So that would enter an "undefined" configuration which could yield odd results, but typically would just refuse to POST. Checking what the BIOS reports, and what the mainboard/system documentation states regarding memory configurations is a good place to start. Also beyond that using the memtest86+ that is on the Gentoo liveCD/DVD would be another interesting step to see what amount is being reported. Though I've never seen memtest86+ report anything different than the BIOS does, so if it's "short" in your BIOS I wouldn't bother with memtest86+ at all. AFAIK the high memory support should not come into play here at all, in the help documentation it states that is only for 32-bit systems with over 4GB of RAM.
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albright
Advocate
Joined: 16 Nov 2003
Posts: 2588
Location: Near Toronto
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| Posted: Tue Mar 02, 2010 1:08 am Post subject: |
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| Quote: | | AFAIK the high memory support should not come into play here at all, in the help documentation it states that is only for 32-bit systems with over 4GB of RAM |
well, that's not what it says below nor is it my own experience - I needed to enable
himem on my thinkpad with 2gb (x86 of course):
http://kerneltrap.org/node/2450
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BonezTheGoon
Bodhisattva
Joined: 14 Jun 2002
Posts: 1408
Location: Albuquerque, NM -- birthplace of Microsoft and Gentoo
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| Posted: Tue Mar 02, 2010 4:11 pm Post subject: |
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Huh, crazy. I guess on some boards/systems it is needed. Just hasn't been my experience on many 32-bit systems at 4GB. Learn something new every day! Thanks!
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| pjp wrote: | | The greater evil is voting for the "lesser evil." |
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krinn
Watchman
Joined: 02 May 2003
Posts: 7470
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| Posted: Tue Mar 02, 2010 4:33 pm Post subject: |
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| BonezTheGoon wrote: | | which should never be done as dual-channel configuration is supposed to have matching pairs. |
 not anymore, depend on chipset, X38 can do dual channel even pairs don't match.
edit: forgot to said about the problem: might also be memory eaten by onboard video card if one is present. |
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xiaweitang
Apprentice
Joined: 26 Feb 2010
Posts: 152
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| Posted: Tue Mar 02, 2010 10:09 pm Post subject: |
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| Problem fixed after enabling 4GB high memory support. By the way, How do I mark a post as solved? |
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Ant P.
Watchman
Joined: 18 Apr 2009
Posts: 6920
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| Posted: Tue Mar 02, 2010 11:01 pm Post subject: |
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| Just edit the subject line in the first post. |
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