System information

System Monitoring Utilities 31
Mapped
Memory claimed with the mmap system call
Slab
Kernel data structure cache
SReclaimable
Reclaimable slab caches (inode, dentry, etc.)
Committed_AS
An approximation of the total amount of memory (RAM plus swap) the current
workload needs in the worst case.
2.4.3 Process Memory Usage: smaps
Exactly determining how much memory a certain process is consuming is not possi-
ble with standard tools like top or ps. Use the smaps subsystem, introduced in Ker-
nel 2.6.14, if you need exact data. It can be found at /proc/pid/smaps and shows
you the number of clean and dirty memory pages the process with the ID PID is us-
ing at that time. It differentiates between shared and private memory, so you are able
to see how much memory the process is using without including memory shared with
other processes.
2.5 Networking
2.5.1 Basic Network Diagnostics: ifconfig
ifconfig is a powerful tool to set up and control network interfaces. As well as
this, you can use it to quickly view basic statistics about one or all network interfaces
present in the system, such as whether the interface is up, the number of errors or
dropped packets, or packet collisions.
If you run ifconfig with no additional parameter, it lists all active network inter-
faces. ifconfig -a lists all (even inactive) network interfaces, while ifconfig
net_interface lists statistics for the specified interface only.
# ifconfig br0
br0 Link encap:Ethernet HWaddr 00:25:90:98:6A:00
inet addr:10.100.2.76 Bcast:10.100.63.255 Mask:255.255.192.0