4GB de 8GB total reservado 64bit 12.04 porque

Question

Alguém pode explicar por que 50% do meu carneiro está sendo reservado e para quê? Eu tenho duas placas Radeon 7990, mas certamente o RAM não está reservado para elas?

root@stan-desktop:/home/stan# cat /etc/issue
Ubuntu 12.04.3 LTS \n \l

root@stan-desktop:/home/stan# uname -a
Linux stan-desktop 3.8.0-35-generic #50~precise1-Ubuntu SMP Wed Dec 4 17:25:51 UTC 2013 x86_64 x86_64 x86_64 GNU/Linux
root@stan-desktop:/home/stan# cat /etc/issue^C
root@stan-desktop:/home/stan# cat /etc/issue
Ubuntu 12.04.3 LTS \n \l

root@stan-desktop:/home/stan# free -m
             total       used       free     shared    buffers     cached
Mem:          3912       1571       2341          0         81        625
-/+ buffers/cache:        863       3048
Swap:         8148          0       8148
root@stan-desktop:/home/stan# uname -a
Linux stan-desktop 3.8.0-35-generic #50~precise1-Ubuntu SMP Wed Dec 4 17:25:51 UTC 2013 x86_64 x86_64 x86_64 GNU/Linux
root@stan-desktop:/home/stan# lshw -c memory
  *-firmware              
       description: BIOS
       vendor: American Megatrends Inc.
       physical id: 0
       version: P1.50
       date: 10/12/2012
       size: 64KiB
       capacity: 4032KiB
       capabilities: pci upgrade shadowing cdboot bootselect socketedrom edd int13floppy1200 int13floppy720 int13floppy2880 int5printscreen int9keyboard int14serial int17printer acpi usb biosbootspecification
  *-cache:0
       description: L1 cache
       physical id: 5
       slot: L1-Cache
       size: 192KiB
       capacity: 192KiB
       clock: 1GHz (1.0ns)
       capabilities: pipeline-burst internal write-back unified
  *-cache:1
       description: L2 cache
       physical id: 6
       slot: L2-Cache
       size: 4MiB
       capacity: 4MiB
       clock: 1GHz (1.0ns)
       capabilities: pipeline-burst internal write-back unified
  *-cache:2
       description: L3 cache
       physical id: 7
       slot: L3-Cache
       size: 4MiB
       capacity: 4MiB
       clock: 1GHz (1.0ns)
       capabilities: pipeline-burst internal write-back unified
  *-memory
       description: System Memory
       physical id: f
       slot: System board or motherboard
       size: 8GiB
     *-bank:0
          description: DIMM DDR3 Synchronous 667 MHz (1.5 ns)
          product: PSD34G133381
          vendor: Undefined
          physical id: 0
          serial: 00000000
          slot: A1_DIMM0
          size: 4GiB
          width: 64 bits
          clock: 667MHz (1.5ns)
     *-bank:1
          description: DIMM Synchronous [empty]
          product: Array1_PartNumber1
          vendor: A1_Manufacturer1
          physical id: 1
          serial: A1_SerNum1
          slot: A1_DIMM1
     *-bank:2
          description: DIMM DDR3 Synchronous 667 MHz (1.5 ns)
          product: PSD34G133381
          vendor: Undefined
          physical id: 2
          serial: 00000000
          slot: A1_DIMM2
          size: 4GiB
          width: 64 bits
          clock: 667MHz (1.5ns)
     *-bank:3
          description: DIMM Synchronous [empty]
          product: Array1_PartNumber3
          vendor: A1_Manufacturer3
          physical id: 3
          serial: A1_SerNum3
          slot: A1_DIMM3
root@stan-desktop:/home/stan# dmesg | grep e820
[    0.000000] e820: BIOS-provided physical RAM map:
[    0.000000] BIOS-e820: [mem 0x0000000000000000-0x000000000009ffff] usable
[    0.000000] BIOS-e820: [mem 0x0000000000100000-0x000000008e1e2fff] usable
[    0.000000] BIOS-e820: [mem 0x000000008e1e3000-0x000000008e4f5fff] reserved
[    0.000000] BIOS-e820: [mem 0x000000008e4f6000-0x000000008e8defff] ACPI NVS
[    0.000000] BIOS-e820: [mem 0x000000008e8df000-0x000000008ee31fff] reserved
[    0.000000] BIOS-e820: [mem 0x000000008ee32000-0x000000008ee32fff] usable
[    0.000000] BIOS-e820: [mem 0x000000008ee33000-0x000000008f038fff] ACPI NVS
[    0.000000] BIOS-e820: [mem 0x000000008f039000-0x000000008f452fff] usable
[    0.000000] BIOS-e820: [mem 0x000000008f453000-0x000000008f7f3fff] reserved
[    0.000000] BIOS-e820: [mem 0x000000008f7f4000-0x000000008f7fffff] usable
[    0.000000] BIOS-e820: [mem 0x00000000fec00000-0x00000000fec00fff] reserved
[    0.000000] BIOS-e820: [mem 0x00000000fec10000-0x00000000fec10fff] reserved
[    0.000000] BIOS-e820: [mem 0x00000000fec20000-0x00000000fec20fff] reserved
[    0.000000] BIOS-e820: [mem 0x00000000fed00000-0x00000000fed00fff] reserved
[    0.000000] BIOS-e820: [mem 0x00000000fed61000-0x00000000fed70fff] reserved
[    0.000000] BIOS-e820: [mem 0x00000000fed80000-0x00000000fed8ffff] reserved
[    0.000000] BIOS-e820: [mem 0x00000000fef00000-0x00000000ffffffff] reserved
[    0.000000] BIOS-e820: [mem 0x0000000100001000-0x000000016effffff] usable
[    0.000000] e820: update [mem 0x00000000-0x0000ffff] usable ==> reserved
[    0.000000] e820: remove [mem 0x000a0000-0x000fffff] usable
[    0.000000] e820: last_pfn = 0x16f000 max_arch_pfn = 0x400000000
[    0.000000] e820: update [mem 0x8f800000-0xffffffff] usable ==> reserved
[    0.000000] e820: last_pfn = 0x8f800 max_arch_pfn = 0x400000000
[    0.000000] e820: [mem 0x8f800000-0xfebfffff] available for PCI devices
[    0.347889] e820: reserve RAM buffer [mem 0x8e1e3000-0x8fffffff]
[    0.347891] e820: reserve RAM buffer [mem 0x8ee33000-0x8fffffff]
[    0.347892] e820: reserve RAM buffer [mem 0x8f453000-0x8fffffff]
[    0.347893] e820: reserve RAM buffer [mem 0x8f800000-0x8fffffff]
[    0.347895] e820: reserve RAM buffer [mem 0x16f000000-0x16fffffff]
root@stan-desktop:/home/stan# cat /proc/meminfo
MemTotal:        4006400 kB
MemFree:         2397856 kB
Buffers:           83668 kB
Cached:           640776 kB
SwapCached:            0 kB
Active:           594800 kB
Inactive:         477904 kB
Active(anon):     349120 kB
Inactive(anon):      232 kB
Active(file):     245680 kB
Inactive(file):   477672 kB
Unevictable:           0 kB
Mlocked:               0 kB
SwapTotal:       8344572 kB
SwapFree:        8344572 kB
Dirty:                 0 kB
Writeback:             0 kB
AnonPages:        348256 kB
Mapped:           261108 kB
Shmem:              1096 kB
Slab:              96600 kB
SReclaimable:      65196 kB
SUnreclaim:        31404 kB
KernelStack:        3016 kB
PageTables:        24424 kB
NFS_Unstable:          0 kB
Bounce:                0 kB
WritebackTmp:          0 kB
CommitLimit:    10347772 kB
Committed_AS:    1839192 kB
VmallocTotal:   34359738367 kB
VmallocUsed:      387712 kB
VmallocChunk:   34359347964 kB
HardwareCorrupted:     0 kB
AnonHugePages:         0 kB
HugePages_Total:       0
HugePages_Free:        0
HugePages_Rsvd:        0
HugePages_Surp:        0
Hugepagesize:       2048 kB
DirectMap4k:      362492 kB
DirectMap2M:     3807232 kB
DirectMap1G:           0 kB
root@stan-desktop:/home/stan# 

    

Answer 1

Eu não me incomodaria com o Ubuntu usando metade da minha memória RAM, como é normalmente usado para armazenar informações em cache para poder acessá-las com muita rapidez. Então o cache, tanto quanto possível (por exemplo, do seu disco rígido) é o melhor que o Ubuntu pode fazer, desde que haja muito espaço para outras aplicações e não seja necessário usar o swap. Mas se você estiver interessado em quais processos estão ocupando a memória, tente top ou htop , que deve fornecer uma saída semelhante à guia de processos do gerenciador de tarefas do Windows. Mais infos: descrição superior / lista de ferramentas de monitoramento