Red Hat ENTERPRISE LINUX 5 - DEPLOYMENT Deployment Manual page 76

Chapter 3. The proc File System
/usr/share/doc/kernel-doc-<version>/Documentation/filesystems/proc.txt
• max_map_count — Configures the maximum number of memory map areas a process may have.
In most cases, the default value of 65536 is appropriate.
• min_free_kbytes — Forces the Linux VM (virtual memory manager) to keep a minimum number
of kilobytes free. The VM uses this number to compute a pages_min value for each lowmem zone
in the system. The default value is in respect to the total memory on the machine.
• nr_hugepages — Indicates the current number of configured hugetlb pages in the kernel.
For more information, refer to the following installed documentation:
/usr/share/doc/kernel-doc-<version>/Documentation/vm/hugetlbpage.txt
• nr_pdflush_threads — Indicates the number of pdflush daemons that are currently running.
This file is read-only, and should not be changed by the user. Under heavy I/O loads, the default
value of two is increased by the kernel.
• overcommit_memory — Configures the conditions under which a large memory request is
accepted or denied. The following three modes are available:
• 0 — The kernel performs heuristic memory over commit handling by estimating the amount of
memory available and failing requests that are blatantly invalid. Unfortunately, since memory
is allocated using a heuristic rather than a precise algorithm, this setting can sometimes allow
available memory on the system to be overloaded. This is the default setting.
• 1 — The kernel performs no memory over commit handling. Under this setting, the potential for
memory overload is increased, but so is performance for memory intensive tasks (such as those
executed by some scientific software).
• 2 — The kernel fails requests for memory that add up to all of swap plus the percent of physical
RAM specified in /proc/sys/vm/overcommit_ratio. This setting is best for those who desire
less risk of memory overcommitment.
Note
This setting is only recommended for systems with swap areas larger than physical
memory.
• overcommit_ratio — Specifies the percentage of physical RAM considered when /proc/sys/
vm/overcommit_memory is set to 2. The default value is 50.
• page-cluster — Sets the number of pages read in a single attempt. The default value of 3, which
actually relates to 16 pages, is appropriate for most systems.
• swappiness — Determines how much a machine should swap. The higher the value, the more
swapping occurs. The default value, as a percentage, is set to 60.
All kernel-based documentation can be found in the following locally installed location:
/usr/share/doc/kernel-doc-<version>/Documentation/, which contains additional
information.
50