Re: [PATCH] sched: Support current clocksource handling in fallbacksched_clock().

From: Thomas Gleixner
Date: Thu May 28 2009 - 14:45:48 EST

On Thu, 28 May 2009, Daniel Walker wrote:
> On Fri, 2009-05-29 at 02:53 +0900, Paul Mundt wrote:
> > As I already stated, yes.
> >
> > We have multiple clock sources for most CPUs. These can be set up in any
> > sort of configuration, and there are pros and cons to using different
> > ones. The ones that are available can in turn be cycled between. I don't
> > know what exactly is difficult to understand about this.
> I understand that cpu's can have multiple clocks, that's not a hard concept to grasp.
> > Yes, we want to be able to use modular clocksources. The only reason we
> > don't right now is because some more preparatory work is needed first.
> > Any attempt to remove support for modular clocksources means we will just
> > have to add it in back later.
> This is what's difficult to understand.. You have multiple clocks ok,
> fine.. You have multiple clocks that you want the kernel to switch
> between, ok that's fine too.. What's missing is the case where
> clocksource modules being loaded/unload via the user becomes a valuable
> use case..

Did you actually read what people wrote ? This is not about modules or
not, it's about safe switching of clocksources when they are used for
sched_clock as well.

> If you have a valuable use case for that, fine, I won't stand in the
> way ..


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