Meu laptop do Kubuntu
$ uname -a
Linux jiggs 3.16.0-31-generic #43-Ubuntu SMP Tue Mar 10 17:37:36 UTC 2015 x86_64 x86_64 x86_64 GNU/Linux
tem 6GiB de memória:
# lshw -C memory
*-firmware
description: BIOS
vendor: TOSHIBA
physical id: 0
version: Version 6.50
date: 11/26/2012
size: 128KiB
capacity: 8128KiB
capabilities: isa pci pnp upgrade shadowing vesa cdboot bootselect edd int13floppytoshiba int13floppy720 int5printscreen int9keyboard int14serial int17printer acpi usb biosbootspecification netboot
*-memory
description: System Memory
physical id: 1f
slot: System board or motherboard
size: 6GiB
*-bank:0
description: SODIMM DDR3 Synchronous 1600 MHz (0,6 ns)
product: HMT351S6CFR8C-PB
vendor: Hynix/Hyundai
physical id: 0
serial: 3F720214
slot: DIMM0
size: 4GiB
width: 64 bits
clock: 1600MHz (0.6ns)
*-bank:1
description: SODIMM DDR3 Synchronous 1600 MHz (0,6 ns)
product: HMT325S6CFR8C-PB
vendor: Hynix/Hyundai
physical id: 1
serial: 046584F8
slot: DIMM2
size: 2GiB
width: 64 bits
clock: 1600MHz (0.6ns)
do qual eu deduzo que tenho (como minha lembrança das especificações no momento da compra me serve) 6GiBs.
No entanto, outros instrumentos relatam o contrário:
$ vmstat -s
4942348 K total memory
3043944 K used memory
1591504 K active memory
1160736 K inactive memory
1898404 K free memory
93484 K buffer memory
810816 K swap cache
4194300 K total swap
242832 K used swap
3951468 K free swap
7151425 non-nice user cpu ticks
22453 nice user cpu ticks
401211 system cpu ticks
94036935 idle cpu ticks
62616 IO-wait cpu ticks
246 IRQ cpu ticks
3030 softirq cpu ticks
0 stolen cpu ticks
1570974 pages paged in
9494712 pages paged out
1695 pages swapped in
18084 pages swapped out
87647428 interrupts
199120848 CPU context switches
1426162570 boot time
41765 forks
ou
$ free -h
total used free shared buffers cached
Mem: 4,7G 2,9G 1,8G 209M 91M 796M
-/+ buffers/cache: 2,0G 2,7G
Swap: 4,0G 237M 3,8G
ou, finalmente,
$ cat /proc/meminfo
MemTotal: 4942348 kB
MemFree: 1892556 kB
MemAvailable: 2483472 kB
Buffers: 93844 kB
Cached: 815388 kB
SwapCached: 180524 kB
Active: 1595312 kB
Inactive: 1162484 kB
Active(anon): 1128632 kB
Inactive(anon): 934308 kB
Active(file): 466680 kB
Inactive(file): 228176 kB
Unevictable: 68 kB
Mlocked: 68 kB
SwapTotal: 4194300 kB
SwapFree: 3951468 kB
Dirty: 0 kB
Writeback: 0 kB
AnonPages: 1671124 kB
Mapped: 296016 kB
Shmem: 214376 kB
Slab: 167272 kB
SReclaimable: 130004 kB
SUnreclaim: 37268 kB
KernelStack: 9552 kB
PageTables: 56688 kB
NFS_Unstable: 0 kB
Bounce: 0 kB
WritebackTmp: 0 kB
CommitLimit: 6665472 kB
Committed_AS: 6178500 kB
VmallocTotal: 34359738367 kB
VmallocUsed: 354304 kB
VmallocChunk: 34359375180 kB
HardwareCorrupted: 0 kB
AnonHugePages: 638976 kB
HugePages_Total: 0
HugePages_Free: 0
HugePages_Rsvd: 0
HugePages_Surp: 0
Hugepagesize: 2048 kB
DirectMap4k: 75328 kB
DirectMap2M: 5027840 kB
Esta última saída é possivelmente importante porque não relata qualquer problema de hardware: HardwareCorrupted = 0 kB . De onde a discrepância?
EDIT: @Sobrique corretamente aponta que eu deveria ter incluído as informações da BIOS:
Total Memory Size 6140MB
Editar2:
# dmesg | grep Memory
[ 0.000000] Memory: 5957056K/6166700K available (7384K kernel code, 1145K rwdata, 3408K rodata, 1336K init, 1444K bss, 209644K reserved)
[ 1.201086] [drm] Memory usable by graphics device = 2048M