Re: [RFC][PATCH 0/5] Introduce checks for preemptable code for this_cpu_read/write()

Christoph Lameter
2011-09-20T14:58:47Z

On Tue, 20 Sep 2011, Thomas Gleixner wrote:

> > What's the latency hit on those very few locations if we simply put our
> > collective foot down and not support a preemptable version of this_cpu_*()?
> > "Yes, you *could* preempt here, but for our collective sanity that's not
> > supported"...
>
> Full ack.

Latency hit could be very significant in various critical kernel paths.
Especially network subsystem, vm event counters etc.