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This is the BSDA Study Guide Book written via a wiki collaboration. This is a work in progress. You may contribute to or discuss this specific page at http://bsdwiki.reedmedia.net/wiki/Monitor_the_virtual_memory_system.html.
Monitor the virtual memory system
The virtual memory subsystem may have an important impact on a system's overall performance. Be able to configure a swap device and review swap usage.
TODO: define thrashing ?
TODO: mention NetBSD example?? UVM: pid 8808 (perl), uid 1000 killed: out of swap
TODO: show examples of swap in fstab
TODO: mention start up scripts for enabling swap devices and files and basic setup
TODO: show examples on FreeBSD and test this; is this the preferred beginner way?
TODO: check this DragonFly example:
TODO: show examples of loading swap file on OpenBSD or NetBSD
On NetBSD and OpenBSD, the
NetBSD swap partition example in /etc/fstab:
TODO: show example of swap file in fstab
NetBSD and OpenBSD's
TODO: this topic should not go into detail on virtual memory theory but just quickly explain it
Some tools to quickly show physical and/or virtual memory utilization are pstat, systat, top, and vmstat. On FreeBSD and DragonFly, the swapinfo tool is same as "pstat -s".
The following example lists the enabled swap files and devices:
TODO: should this mention that this is same as 'swapctl -l -k' ??
TODO: mention that DragonFly has "Type" like "Interleaved". I don't see on FreeBSD. TODO: while NetBSD and OpenBSD have "Priority"
TODO: should this mention unloading swap files? some systems may not support unloading sawp devices??
TODO: show how to read top for virtual memory info
TODO: show how to use vmstat for virtual memory info
TODO: show how to use systat for virtual memory info
pstat(8); systat(1); top(1); vmstat(8); swapctl(8); swapinfo(8)
TODO: add swapon(8) and fstab(5)