Re: [RFC][PATCH] avoid cpu hot removal if busy take3

[KAMEZAWA Hiroyuki]

On Fri, 23 Jun 2006 09:27:46 -0500
Nathan Lynch <ntl@xxxxxxxxx> wrote:

> KAMEZAWA Hiroyuki wrote:
> > This patch adds sysctl cpu_removal_migration.
> > If cpu_removal_migration == 1, all tasks are migrated by force.
> > If cpu_removal_migration == 0, cpu_hotremoval can fail because of not-migratable
> > tasks.
> > 
> > Note: cpu scheduler's notifier chain has the highest priority. then, this
> >       failure detection will be done at first.
> 
> I'm still not convinced that this is a good thing to do.  I reiterate:
> this can be implemented in userspace (probably with fewer lines of
> code, even).  Why should this policy be in the kernel?
> 
I don't think so.
If we can expect all things can be maintained by user-space in proper way,
why we need forced migration ? This patch is just one of possible workarounds. 
and implemtns, "success always" and "fail if busy" policy to cpu-hot-remove.

-Kame

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