IPI_PREEMPTION, something to test for normal users?

[Stephan Uphoff]

On Thu, 2005-06-16 at 04:01, Daniel Eriksson wrote:
> On a regular SMP server running 6-CURRENT, is IPI_PREEMPTION something
> to try?
> I've looked around for an explanation of what it does and what possible
> pitfalls there are, but I haven't really found anything. It's only in
> NOTES at the moment, indicating that it isn't for general consumption
> yet(?).

IPI_PREEMPTION allows the scheduler running on CPU A to preempt a thread
on CPU B. This should reduce latency in some circumstances.

More benchmarks are needed to find out if this actually helps or if
additional context switch overhead slows down typical workloads.

The preemption IPI could also be (ab)used later to add security fixes
for hyperthreading as proposed by Colin Percival.

Stephan