11-26-2012
Quote:
Originally Posted by
vistastar
I thought OS don't allocate any swap area nor physical memory to a new got virtual space
That depends on how you define "allocate". Most OSes do either a partial or a full memory reservation. This reservation is backed by available disk and ram combined
Quote:
but allocate physical pages directly when this space is written/read, and swap out when done some thing.
You are describing pagination more than allocation.
Quote:
Do you mean, OS allocate swap area to a process when it use malloc to ask for memory, but swap it into physical memory when this space is written/read?
No. I mean most Unix OSes reserve (some or all of the allocated) space and this space must exist somewhere, whether in RAM or on disk or on tape or whatever doesn't matter.
Last edited by jlliagre; 11-26-2012 at 09:17 AM..
This User Gave Thanks to jlliagre For This Post:
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LEARN ABOUT DEBIAN
virtual-filesystems
virtual-filesystems(7) Miscellaneous Information Manual virtual-filesystems(7)
NAME
virtual-filesystems - event signalling that virtual filesystems have been mounted
SYNOPSIS
virtual-filesystems [ENV]...
DESCRIPTION
The virtual-filesystems event is generated by the mountall(8) daemon after it has mounted all virtual filesystems listed in fstab(5).
mountall(8) emits this event as an informational signal, services and tasks started or stopped by this event will do so in parallel with
other activity.
This event is typically used by services that must be started in order to mount other filesystems. When this event occurs, common filesys-
tems such as /usr may not be mounted. For most normal services the filesystem(7) event is sufficient.
EXAMPLE
A service that wishes to be running once virtual filesystems are mounted might use:
start on virtual-filesystems
SEE ALSO
mounting(7) mounted(7) local-filesystems(7) remote-filesystems(7) all-swaps(7) filesystem(7)
mountall 2009-12-21 virtual-filesystems(7)