3.2.19. /proc/meminfo

3.2.19. /proc/meminfo

This is one of the more commonly used files in the /proc/ directory, as it reports a large amount of valuable information about the systems RAM usage.

The following sample /proc/meminfo virtual file is from a system with 256 MB of RAM and 512 MB of swap space:

MemTotal:       255908 kB 
MemFree:         69936 kB 
Buffers:         15812 kB 
Cached:         115124 kB 
SwapCached:          0 kB 
Active:          92700 kB 
Inactive:        63792 kB 
HighTotal:           0 kB 
HighFree:            0 kB 
LowTotal:       255908 kB 
LowFree:         69936 kB 
SwapTotal:      524280 kB 
SwapFree:       524280 kB 
Dirty:               4 kB 
Writeback:           0 kB 
Mapped:          42236 kB 
Slab:            25912 kB 
Committed_AS:   118680 kB 
PageTables:       1236 kB 
VmallocTotal:  3874808 kB 
VmallocUsed:      1416 kB 
VmallocChunk:  3872908 kB 
HugePages_Total:     0 
HugePages_Free:      0 
Hugepagesize:     4096 kB

Much of the information here is used by the free, top, and ps commands. In fact, the output of the free command is similar in appearance to the contents and structure of /proc/meminfo. But by looking directly at /proc/meminfo, more details are revealed:

Note: This documentation is provided {and copyrighted} by Red Hat®, Inc. and is released via the Open Publication License. The copyright holder has added the further requirement that Distribution of substantively modified versions of this document is prohibited without the explicit permission of the copyright holder. The CentOS project redistributes these original works (in their unmodified form) as a reference for CentOS-5 because CentOS-5 is built from publicly available, open source SRPMS. The documentation is unmodified to be compliant with upstream distribution policy. Neither CentOS-5 nor the CentOS Project are in any way affiliated with or sponsored by Red Hat®, Inc.