![Red hat 6(来自 vmware 的来宾主机)丢失内存](https://linux22.com/image/93460/Red%20hat%206%EF%BC%88%E6%9D%A5%E8%87%AA%20vmware%20%E7%9A%84%E6%9D%A5%E5%AE%BE%E4%B8%BB%E6%9C%BA%EF%BC%89%E4%B8%A2%E5%A4%B1%E5%86%85%E5%AD%98.png)
VMware Virtual Center 2.5.0
分配给 GuestOS 的资源:RHEL 5(64 位)
内存:4608MB
内存开销:261 MB
[root@stend-mcstesb /]# cat /etc/redhat-release
Red Hat Enterprise Linux Server release 6.6 (Santiago)
[root@stend-mcstesb /]# cat /proc/meminfo
MemTotal: 4180644 kB
MemFree: 146068 kB
Buffers: 143936 kB
Cached: 211212 kB
SwapCached: 37924 kB
Active: 3038872 kB
Inactive: 876464 kB
Active(anon): 2857224 kB
Inactive(anon): 702968 kB
Active(file): 181648 kB
Inactive(file): 173496 kB
Unevictable: 0 kB
Mlocked: 0 kB
SwapTotal: 2097148 kB
SwapFree: 1240480 kB
Dirty: 2444 kB
Writeback: 0 kB
AnonPages: 3548036 kB
Mapped: 11084 kB
Shmem: 4 kB
Slab: 55728 kB
SReclaimable: 32480 kB
SUnreclaim: 23248 kB
KernelStack: 2968 kB
PageTables: 11688 kB
NFS_Unstable: 0 kB
Bounce: 0 kB
WritebackTmp: 0 kB
CommitLimit: 4187468 kB
Committed_AS: 4440116 kB
VmallocTotal: 34359738367 kB
VmallocUsed: 26468 kB
VmallocChunk: 34359706956 kB
HardwareCorrupted: 0 kB
AnonHugePages: 3411968 kB
HugePages_Total: 0
HugePages_Free: 0
HugePages_Rsvd: 0
HugePages_Surp: 0
Hugepagesize: 2048 kB
DirectMap4k: 10240 kB
DirectMap2M: 4446208 kB
[root@stend-mcstesb /]# free -m
total used free shared buffers cached
Mem: 4082 3939 143 0 140 206
-/+ buffers/cache: 3592 490
Swap: 2047 836 1211
dmidecode -t 17 显示 2 个 2048MB 插槽和 1 个 512MB 插槽
dmidecode -t 16 显示最大容量:4 GB
dmidecode -t 2 show 产品名称:440BX 桌面参考平台
检查其他具有 8GB RAM 的 guestOS(rhel/windows),也丢失了 ~0.5GB(rhel) ~0.25GB(Windows)。 Windows AGP 256MB 可以,但是 rhel 可以吗?
哪里丢了4608-4082=526MB?
答案1
https://access.redhat.com/solutions/454133
内核在启动时为内存表(用于虚拟到物理地址的转换)保留一定量的内存(与其总大小成比例)。分配给内存表的内存不能被其他任何东西使用,并且会从报告的总内存大小中减去。
物理 RAM 大小越大,无法使用的内存占物理 RAM 总大小的比例越小:
On 12Gb desktop this ratio is around 4.5%
On 32Gb server this ratio is around 2%
On 512Gb server this ratio is around 1.56%
回答 REDHAT:这不是一个错误,而是一个功能。