"Stephen C. Tweedie" wrote:
> 
> Hi,
> 
> On Wed, Jun 28, 2000 at 11:52:40AM -0500, lord@sgi.com wrote:
> >
> > I am not a VM guy either, Ben, is the cost of the TLB flush mostly in
> > the synchronization between CPUs, or is it just expensive anyway you
> > look at it?
> 
> The TLB IPI is by far the biggest factor here.
> 
I tried it on my Dual Pentium II/350, 100 MHz FSB:

* an empty IPI returns after ~ 1630 cpu ticks.
* a tlb flush IPI needs ~ 2130 cpu ticks.

The computer was idle, and obviously I only measure the cost as seen
from the primary cpu, I don't know how long the second cpu needs until
it returns from the interrupt.


--
	Manfred