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I have a dual Xeon CPU setup (motherboard Asus Z8NA-D6) with 24 GB of memory (12 GB per CPU). I can't see 24GB of memory in /proc/meminfo but I can see it in /sys/devices/system/node/node0/meminfo:

$ cat /proc/meminfo
MemTotal:       13810952 kB
[..]
$ cat /sys/devices/system/node/node0/meminfo
Node 0 MemTotal:       25156668 kB
[..]

and with numactl:

$ numactl --hardware
available: 1 nodes (0)
node 0 cpus: 0 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15
node 0 size: 24567 MB
node 0 free: 146 MB
node distances:
node   0 
  0:  10

I'm not very familiar with NUMA but I have the following in kern.log:

$ dmesg | grep -i numa
[    0.000000] NUMA turned off

Is my 24GB memory available ? System tools such as 'top', 'free',... reports the same amount of memory as /proc/meminfo.

It is a Debian kernel build but according to the config file, NUMA support is enabled.

kernel: Linux 3.2.0-4-amd64 #1 SMP Debian 3.2.60-1+deb7u3

I also add a look in the BIOS and I didn't see any setting related to NUMA or memory (BIOS report correct memory size). Any help is appreciated. Thank you.

Lienj
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  • What did kernel write in BIOS-e820 lines during kernel initializing? – Netch Aug 25 '14 at 09:45
  • `[ 0.000000] e820 update range: 0000000000000000 - 0000000000010000 (usable) ==> (reserved) [ 0.000000] e820 remove range: 00000000000a0000 - 0000000000100000 (usable)` I also have the following: `[ 0.000000] BIOS bug: APIC version is 0 for CPU 0/0x0, fixing up to 0x10` – Lienj Aug 25 '14 at 11:16
  • Complete dmesg output here [link](http://pastebin.com/iXABVCgt) – Lienj Aug 25 '14 at 13:39

1 Answers1

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Use "free" command, check the row "buffers/cache", the value at the used column is the real active used memory of your system. Here is 1130MB on my system.

free -m
                 total       used       free     shared    buffers     cached
    Mem:          1840       1456        384          0          9        316
    -/+ buffers/cache:       1130        710
    Swap:         1999        216       1783
just_a_newbie
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  • Well I've create multiple Xen VM and the 24GB memory are there. I still dont' understand how /proc/meminfo works though. – Lienj Aug 26 '14 at 09:46