On Wed, Jan 22, 2014 at 04:21:42PM +1100, Daniel Jitnah wrote:
> I have tried that (free --si) , it reports 778 (or something like
> that_.  Btw its Debian 7.
>
> The value 761 also seems like a weird number?
>
> Has anyone had any issue with Debian reporting wrong memory?

some vaguely relevant thoughts in no particular order:


the kernel always uses some ram for itself, and any data in tmpfs
filesystems will use ram too.  

220MB or 240MB out of 1GB sounds like a lot, though....is the initrd
still mounted? or maybe some ram is being reserved for a video card or
other device (unlikely, most VMs only use around 10M or so for video
emulation)?  

IMO, the most likely culprit is your VM hypervisor - kvm or xen? or
maybe your kernel version - do you get different values for 'free' with
different kernels?

try grepping for "Memory" in /var/log/dmesg, e.g. on my 16GB system I
get:

# uname -a
Linux ganesh 3.10-2-amd64 #1 SMP Debian 3.10.7-1 (2013-08-17) x86_64 GNU/Linux

# grep Memory /var/log/dmesg
[    0.000000] Memory: 16346352k/17563648k available (3642k kernel code, 
826012k absent, 391284k reserved, 3127k data, 920k init)

# free -m
             total       used       free     shared    buffers     cached
Mem:         16047      15695        351        146          0        829
-/+ buffers/cache:      14866       1181
Swap:         8191       3681       4510


(note: "absent" memory is irrelevant and can be ignored, it just
indicates gaps in the motherboard's memory map...it's not actually
missing memory - for details, see
http://serverfault.com/questions/220626/debian-squeeze-and-available-memory-1gb-absent
 ).

some other words to grep for are (case-insensitive) "mem" and "ram".


also, has the VM been allocated 1000M or 1024M? it's not that great a
difference, but it all adds up.


craig

-- 
craig sanders <[email protected]>
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