memstat - Identify what’s using up virtual memory.
memstat [-w][-p PID]
memstat lists all accessible processes, executables, and shared
libraries that are using up virtual memory. To get a complete list
memstat has to be run as root to be able to access the data of all
First, the processes are listed. An amount of memory is shown along
with a process ID and the name of the executable which the process is
running. The amount of memory shown does not include shared memory: it
only includes memory which is private to that process. So, if a
process is using a shared library like libc, the memory used to hold
that library is not included. The memory used to hold the executable’s
text-segment is also not included, since that too is shareable.
After the processes, the shared objects are listed. The amount of
memory is shown along with the filename of the shared object, followed
by a list of the processes using the shared object. The memory is
listed as the total amount of memory allocated to this object
throughout the whole namespace. In brackets also the amount that is
really shared is listed.
Finally, a grand total is shown. Note that this program shows the
amount of virtual (not real) memory used by the various items.
memstat gets its input from the /proc filesystem. This must be
compiled into your kernel and mounted for memstat to work. The
pathnames shown next to the shared objects are determined by scanning
the disk. memstat uses a configuration file, /etc/memstat.conf, to
determine which directories to scan. This file should include all the
major bin and lib directories in your system, as well as the /dev
directory. If you run an executable which is not in one of these
directories, it will be listed by memstat as ‘‘[0dev]:<inode>’’.
The -w switch causes a wide printout: lines are not truncated at 80
The -p switch causes memstat to only print data gathered from looking
at the process with the gicen PID.
These reports are intended to help identify programs that are using an
excessive amount of memory, and to reduce overall memory waste.
ps(1), top(1), free(1), vmstat(8), lsof(8),
memstat ignores all devices that just map main memory, though this may
cause memstat to ignore some memory usage.
Memory used by the kernel itself is not listed.
Originally written by Joshua Yelon <firstname.lastname@example.org> and patched by
Bernd Eckenfels <email@example.com>. Taken over and rewritten by Michael