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[[!meta copyright="Copyright © 2002, 2003, 2010 Free Software Foundation,
Inc."]]
[[!meta license="""[[!toggle id="license" text="GFDL 1.2+"]][[!toggleable
id="license" text="Permission is granted to copy, distribute and/or modify this
document under the terms of the GNU Free Documentation License, Version 1.2 or
any later version published by the Free Software Foundation; with no Invariant
Sections, no Front-Cover Texts, and no Back-Cover Texts. A copy of the license
is included in the section entitled [[GNU Free Documentation
License|/fdl]]."]]"""]]
A Mach *task* is a collection of resources, a [[virtual_address_space]], and a
[[port name space|port]]. They depend on [[thread]]s for executing program
code: a task alone has no means to do so.
Switching from one task to another one involves doing a *context switch*, which
is usually not a cheap operation, as it involves switching the hardware's idea
of the memory layout ([[virtual_address_space]]), amongst others.
Mach tasks are distinct from [[UNIX processes|unix/process]] in that they
provide less facilities. In processes, there are [[unix/signal]]s, process /
group / session IDs, [[unix/file_descriptor]]s and many other things. Tasks
are used for resource allocation and sharing; they are *resource container*s.
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