FWIW: Its actually because of memory over-committment using ballooning virtio device. In theory the VM should get back the missing memory when needed, assuming its available elsewhere on the host!!!
Daniel. On 22/01/14 19:20, Craig Sanders wrote: > 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 > _______________________________________________ luv-main mailing list [email protected] http://lists.luv.asn.au/listinfo/luv-main
