Messages in this thread | | | Date | Wed, 14 Mar 2007 19:36:43 -0500 | From | Robin Holt <> | Subject | Re: [PATCH 1/1] hotplug cpu: migrate a task within its cpuset |
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On Fri, Mar 09, 2007 at 05:58:59PM -0600, Nathan Lynch wrote: > Hello- > > Cliff Wickman wrote: > > This patch would insert a preference to migrate such a task to a cpu within > > its cpuset (and set its cpus_allowed to its cpuset). > > > > With this patch, migrate the task to: > > 1) to any cpu on the same node as the disabled cpu, which is both online > > and among that task's cpus_allowed > > 2) to any online cpu within the task's cpuset > > 3) to any cpu which is both online and among that task's cpus_allowed > > I think I disagree with this change. > > The kernel shouldn't have to be any smarter than it already is about > moving tasks off an offlined cpu. The only way case 2) can be reached > is if the user has changed a task's cpu affinity. If the user is > sophisticated enough to manipulate tasks' cpu affinity then they can > arrange to migrate tasks as they see fit before offlining a cpu.
You are assuming some sort of interlock between the admin and the user. While this may be true on your own personal desktop, I don't think you can expect this to be true on a development machine shared by hundreds of users and admin'd by a group of people.
Additionally, ia64 is gaining support for offlining a cpu which is giving cache errors.
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