machdep.cpu_idle_hlt and SMP perf?

[M. Warner Losh]

In message: <43E45BD8.7070708 at fer.hr>
            Ivan Voras <ivoras at fer.hr> writes:
: Andrew Gallatin wrote:
: > Why dooes machdep.cpu_idle_hlt=1 drop my 10GbE network rx
: > performance by a considerable amount (7.5Gbs -> 5.5Gbs)?
: 
: For what it's worth, here are results of unixbench's "context1" 
: benchmark on an old P3 SMP with and without cpu_idle_hlt (6-stable):

When ACPI CPU states were coming into the tree, there was discussion
that they had been invented to provide a lower energy idle as well as
a faster transition from the idle state to something else.  I think
that these benchmarks show this effect rather dramatically.

Warner