Entries in /proc/meminfo

Question

I can make sense of most of the information contained in /proc/meminfo like total memory,buffers, cache etc. Could you tell me what do the less obvious ones like *AnonPages,Mapped,Slab,NFS_Unstable,Bounce,VmallocTotal,VmallocUsed,VmallocChunk* mean?

Answer 1

From RedHat

VMallocTotal — The total amount of memory, in kilobytes, of total allocated virtual address space. VMallocUsed — The total amount of memory, in kilobytes, of used virtual address space. VMallocChunk — The largest contiguous block of memory, in kilobytes, of available virtual address space.

Answer 2

The canonical source of this information is /usr/src/linux/Documentation/filesystems/proc.txt. Specifically,

   AnonPages: Non-file backed pages mapped into userspace page tables
      Mapped: files which have been mmaped, such as libraries
        Slab: in-kernel data structures cache
NFS_Unstable: NFS pages sent to the server, but not yet committed to stable
        storage
      Bounce: Memory used for block device "bounce buffers"
VmallocTotal: total size of vmalloc memory area
 VmallocUsed: amount of vmalloc area which is used
VmallocChunk: largest contigious block of vmalloc area which is free

Answer 3

I still haven't understood what this VMallocTotal means. On my system this is what I observe -

$ cat /proc/meminfo
MemTotal:     32909700 kB
MemFree:       2013560 kB
Buffers:        802196 kB
Cached:       10562704 kB
SwapCached:          0 kB
Active:        6687168 kB
Inactive:      8312508 kB
HighTotal:           0 kB
HighFree:            0 kB
LowTotal:     32909700 kB
LowFree:       2013560 kB
SwapTotal:     4194296 kB
SwapFree:      4194072 kB
Dirty:          109408 kB
Writeback:           0 kB
Mapped:        3694660 kB
Slab:          2241316 kB
CommitLimit:  20649144 kB
Committed_AS: 30747988 kB
PageTables:      18396 kB
VmallocTotal: 536870911 kB
VmallocUsed:    268304 kB
VmallocChunk: 536602107 kB
HugePages_Total:     0
HugePages_Free:      0
Hugepagesize:     2048 kB

the value for VmallocTotal seems invalid to me! Any pointers would be helpful.