Anonymous user
Microkernel: Difference between revisions
The memory manager *may* be implemented in userspace - doesn't have to be.
| [unchecked revision] | [unchecked revision] |
(→Design) |
(The memory manager *may* be implemented in userspace - doesn't have to be.) |
||
| (8 intermediate revisions by 6 users not shown) | |||
Line 1:
{{Template:Kernel designs}}
== Design ==
[[Image:Microkernel.png|frame|right|Basic overview of a microkernel]]
A Microkernel tries to run most services - like networking, filesystem, etc. - as daemons / servers in user space. All that's left to do for the kernel are basic services, like physical memory allocation (the actual memory '''manager''' may be implemented in userspace), scheduling, and messaging (Inter Process Communication).
In theory, this concept makes the kernel more responsive (since much functionality resides in preemptible user-space threads and processes, removing the need for context-switching into the kernel proper), and improves the stability of the kernel by reducing the amount of code running in kernel space. There are also additional benefits for OS' that support multi-CPU computers (much simpler re-entrancy protection and better suitability for asynchronious functionality) and distributed OS' (code can use services without knowing if the service provider is running on the same computer or not). A drawback is the amount of messaging and Context Switching involved, which makes microkernels conceptually slower than monolithic kernels. (This isn't to say that a smartly designed microkernel could not beat a foolishly designed monolithic one.)
Line 14:
It's also possible for an OS design to borrow concepts from both monolithic kernels and micro-kernels in order to use the benefits of either method where appropriate.
== Examples ==
* Mach
* QNX
* [[L4]]
* AmigaOS
* [http://minix3.org Minix]
== See Also ==
=== Forum Threads ===
* [[Topic:10099|microkernels]]
* [[Topic:10234|discussing microkernel vs modular macrokernel]]
==== Recommended Reading ====
* [http://www.google.com/search?q=The+Increasing+Irrelevance+of+IPC+Performance+for+Microkernel-Based+Operating+Systems The Increasing Irrelevance of IPC performance in Microkernel-based Operating Systems] by Brian N. Bershad
* [http://www.google.com/search?q=The+Persistent+Relevance+of+IPC+Performance+for+Microkernel-Based+Operating+Systems The Persistent Relevance of IPC performance in Microkernel-based Operating Systems] by Wilson C. Hsieh, M. Frans Kaashoek, and William E. Weihl
* [http://citeseer.ist.psu.edu/408369.html µ-Kernels Must And Can Be Small] by Jochen Liedtke
* [http://linuxfinances.info/info/microkernel.html Microkernel-based OS Efforts] by Christopher Browne
* [http://web.archive.org/web/20140803112320/http://i30www.ira.uka.de/~neider/edu/mkc/mkc.html Microkernel Construction Notes] by Raphael Neider
[[Category:Kernel]]
| |||