12-20-2011
Your questions suggest a bit of confusion between memory and swap; I'll try to explain.
swap is used as a holding area for RAM. When memory gets low, RAM which hasn't been used recently gets copied into swap space then recycled, given to something else. When something tries to use memory which has been copied into swap, it's forced to wait for it to be read back out of storage.
You don't allocate memory versus swap -- it's the same thing as far as a userspace program's concerned. Traditionally, any memory is backed by its own area of swap anyway. It doesn't get used unless needed, but it's there. So you'd want to have at least as much swap as RAM, and potentially more.
This makes it possible to use more memory than you have RAM, by copying excess things into swap so it can make up the difference. This has a significant performance cost, because swap space on disk is much slower than RAM.
Last edited by Corona688; 12-20-2011 at 02:12 PM..
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LEARN ABOUT DEBIAN
vzcalc
vzcalc(8) Containers vzcalc(8)
NAME
vzcalc - calculate resource usage of a container
SYNOPSIS
vzcalc [-v] CTID
DESCRIPTION
This utility displays the share of the host system resources a particular container is using. If the container is running, the current
usage is displayed. High utilization values (>100%) mean the system is overloaded (or the container has an invalid configuration).
Current
Shows the amount of the resources consumed by the container at a given time.
Promised
Shows the resources soft limit values "promised" for a given container.
Max Shows the resources hard limit values "promised" for a given container.
If the -v option is specified, the following additional information is also displayed:
Low Mem
The part of memory residing at lower addresses and directly accessed by the kernel (only makes sense for 32-bit architectures).
Total RAM
Total memory.
Mem+Swap
Amount of memory available for applications (both RAM and swap space).
Alloc Mem
Standard memory allocations made for applications in a container. This is a more "virtual" system resource than RAM or RAM and
swap.
Num. Proc
Number of processes.
OPTIONS
-v Display additional information.
EXIT STATUS
Normally, the exit status is 0. On error, the exit status is 1.
LICENSE
Copyright (C) 2000-2009, Parallels, Inc. Licensed under GNU GPL.
OpenVZ 10 Dec 2009 vzcalc(8)