[问题]512的内存为什么显示为503M？

[ZidaneLiu]

我内存是512的，但是ubuntu系统监视器里确显示的是503.6M，这是怎么回事？
我显卡是独立的64M，。。。
少了的内存应该不会是共享显存用掉的吧

还有一个问题，我用free -m查看的内存空闲数，和系统监视器里显示的空闲数相差很大阿，free -m显示内存有488M已用，而系统监视器里显示的是只有不到50%的内存已用阿，搞不懂。。。。

[syrano]

free显示的第一行，cache算进了内存占用，
第二行，cache没算进内存占用，就和监视器里一样了。

[ZidaneLiu]

哦，那我第一个问题是怎么回事？

[gtr999]

那8M好象是内核抢占的

[flyinflash]

可能是集成显卡占了。

代码： 全选

lee@lee-laptop:~$ free -m
             total       used       free     shared    buffers     cached
Mem:           [color=darkred]494[/color]        486          8          0         26        170
-/+ buffers/cache:        290        204
Swap:         1026        153        873
lee@lee-laptop:~$ lspci
00:00.0 Host bridge: Intel Corporation Mobile 945GM/PM/GMS, 943/940GML and 945GT Express Memory Controller Hub (rev 03)
[color=darkred]00:02.0 VGA compatible controller: Intel Corporation Mobile 945GM/GMS, 943/940GML Express Integrated Graphics Controller (rev 03)[/color]
00:02.1 Display controller: Intel Corporation Mobile 945GM/GMS/GME, 943/940GML Express Integrated Graphics Controller (rev 03)
00:1b.0 Audio device: Intel Corporation 82801G (ICH7 Family) High Definition Audio Controller (rev 02)
00:1c.0 PCI bridge: Intel Corporation 82801G (ICH7 Family) PCI Express Port 1 (rev 02)
00:1c.2 PCI bridge: Intel Corporation 82801G (ICH7 Family) PCI Express Port 3 (rev 02)
00:1c.3 PCI bridge: Intel Corporation 82801G (ICH7 Family) PCI Express Port 4 (rev 02)
00:1d.0 USB Controller: Intel Corporation 82801G (ICH7 Family) USB UHCI Controller #1 (rev 02)
00:1d.1 USB Controller: Intel Corporation 82801G (ICH7 Family) USB UHCI Controller #2 (rev 02)
00:1d.2 USB Controller: Intel Corporation 82801G (ICH7 Family) USB UHCI Controller #3 (rev 02)
00:1d.3 USB Controller: Intel Corporation 82801G (ICH7 Family) USB UHCI Controller #4 (rev 02)
00:1d.7 USB Controller: Intel Corporation 82801G (ICH7 Family) USB2 EHCI Controller (rev 02)
00:1e.0 PCI bridge: Intel Corporation 82801 Mobile PCI Bridge (rev e2)
00:1f.0 ISA bridge: Intel Corporation 82801GBM (ICH7-M) LPC Interface Bridge (rev 02)
00:1f.2 IDE interface: Intel Corporation 82801GBM/GHM (ICH7 Family) SATA IDE Controller (rev 02)
00:1f.3 SMBus: Intel Corporation 82801G (ICH7 Family) SMBus Controller (rev 02)
02:00.0 Ethernet controller: Broadcom Corporation NetXtreme BCM5751M Gigabit Ethernet PCI Express (rev 21)
15:00.0 CardBus bridge: Texas Instruments PCI1510 PC card Cardbus Controller
lee@lee-laptop:~$ 

像我，本来是512 MB 内存的，现在只有4**

[ZidaneLiu]

但我是64M
的独立显卡阿。。。。

[xiangsiaiwen]

1M＝1024K

[JangMunho]

1M＝1024K

行不行啊，中毒了吧，那个说法只在硬盘和闪盘上存在……

[syrano]

内核占了
内核内存布局


几个重要的标记的顺序
-------------------------------------PAGE_OFFET
|
|eg,512M物理内存
|
-------------------------------------highmemory
|
|8M的空洞
|
-------------------------------------VMALLOC_START
|
|用于由vmalloc和ioremap,也叫做非连续内存区
|
-------------------------------------KMAP_BASE和VMALLOC_END(4G-8M)
|
|永久内核映射(4M),有个专用的页表,位于4G-8M---4G-4M之间,用kmap来进行映射
|
-------------------------------------FIXADDR_START(4G-4M)
|
|临时映射（也叫固定映射）
|
-------------------------------------FIXADDR_TOP
|
END

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[super_soul]

－ －！ 这年头内存不值钱。。别这么斤斤计较了。。。。