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authorSamuel Thibault <samuel.thibault@ens-lyon.org>2015-02-18 00:58:35 +0100
committerSamuel Thibault <samuel.thibault@ens-lyon.org>2015-02-18 00:58:35 +0100
commit49a086299e047b18280457b654790ef4a2e5abfa (patch)
treec2b29e0734d560ce4f58c6945390650b5cac8a1b /service_solahart_jakarta_selatan__082122541663/multiprocessing.mdwn
parente2b3602ea241cd0f6bc3db88bf055bee459028b6 (diff)
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-[[!meta copyright="Copyright © 2010, 2011, 2013 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]]."]]"""]]
-
-[[!tag open_issue_documentation open_issue_hurd]]
-
-We would expect that fine-grained, compartmentalized systems, that is,
-microkernel-based multi-server systems in particular, would be ideal candidates
-for applying multiprocessing. That is, however, only true from a first and
-inexperienced point of view: there are many difficulties.
-
-
-# IRC, freenode, #hurd, August / September 2010
-
- <marcusb> silver_hook: because multi-server systems depend on inter-process
- communication, and inter-process communication is many times more
- expensive across cpus
- <marcusb> silver_hook: so you either force interrelated work on the same
- cpu, or suffer heavy penalties. and in a typical fine-grained object
- system, all objects are interconnected!
- <marcusb> silver_hook: resources in today's systems, even in a single node
- with one cpu, but more so in a network, are very non-uniform. scheduling
- these resources efficiently is a huge problem. restricting the resource
- distribution policies in the way microkernel systems tend to do is posing
- serious research challenges
-
-
-# IRC, freenode, #hurd, 2011-07-26
-
- < braunr> 12:03 < CTKArcher> and does the hurd take more advantages in a
- multicore architecture than linux ?
- < braunr> CTKArcher: short answer: no
- < CTKArcher> it's easier to imagine one server pro core than the linux
- kernel divided to be executed on multiple cores
- < braunr> CTKArcher: this approach is less efficient
- < braunr> CTKArcher: threads carry state, both explicit and implicit (like
- cache data)
- < braunr> CTKArcher: switching to another core means resetting and
- refetching this state
- < braunr> it's expensive and there is no gain obtained by doing this
- < braunr> thread migration (having a thread from a client also run in
- servers when making synchronous RPC, even handling its own page faults)
- was implemented in mach4 and is imo a very good thing we should have
- < braunr> CTKArcher: and concerning linux, it's actually very scalable
- < braunr> it's already like if all client threads run in servers (the
- kernel is the servers there)
- < braunr> rcu is used a lot
- < braunr> thread migration already takes into account smt, cores, and numa
- < braunr> it's hard to do something better
- < braunr> (here, thread migration means being dispatched on another cpu)
-
-
-# debian-hurd list
-
-On Thu, Jan 02, 2003 at 05:40:00PM -0800, Thomas Bushnell, BSG wrote:
-> Georg Lehner writes:
->
-> > - One promise of the microkernel architecture is better performance on
-> > multiprocessor systems, or multicomputer systems. What is the status
-> > of Gnu Mach with respect to these.
->
-> This may or may not be true. The Hurd is built around a microkernel
-> architecture because of its conceptual elegance and flexibility.
-> Other touted advantages may be more illusory than real, at least, they
-> aren't something *we* are proclaiming is our motivation.
-
-
----
-
-See also: [[multithreading]].