Re: [RFC PATCH 16/22 -v2] add get_monotonic_cycles

Steven Rostedt
2008-01-17T02:52:23Z

On Wed, 16 Jan 2008, Mathieu Desnoyers wrote:
> >
> > Yep. clocksource_get_cycles() ended up not being as useful as an helper
> > function (I was hoping the arch vsyscall implementations could use it,
> > but they've done too much optimization - although that may reflect a
> > need up the chain to the clocksource structure).
> >
>
> The problem with vsyscall is that we will have a hard time disabling
> preemption :( Therefore, insuring that the read of the data is done in a
> timely manner is hard to do.

You'll have more than a hard time disabling preemption for vsyscall. We'll
need to come up with a better solution then. vsyscall can not modify any
kernel memory, nor can it disable preemption.

-- Steve