Is machdep.cpu_idle_hlt deprecated?

[Ivan Voras]

On 02/05/2011 19:56, Jung-uk Kim wrote:
> On Monday 02 May 2011 10:48 am, Bruce Cran wrote:
>> On Sat, 30 Apr 2011 21:20:28 -0700
>>
>> Jeremy Chadwick<freebsd at jdc.parodius.com>  wrote:
>>> Anyone know if machdep.cpu_idle_hlt still exists?  Taken from
>>> acpi(4) on RELENG_8:
>>
>> It looks like it might have been replaced by machdep.idle:
>>
>> machdep.idle: currently selected idle function
>> machdep.idle_available: list of available idle functions
>>
>> machdep.idle: acpi
>> machdep.idle_available: spin, hlt, acpi,
>
> It seems "machdep.cpu_idle_hlt" was deprecated long ago with this
> commit by jeff (CC'ed):
>
> http://svnweb.freebsd.org/base?view=revision&revision=178471

How likely is this to affect real-world performance on e.g. a busy web 
server? As the comments say, the "fastest" are spin and mwait and the 
slowest is acpi, which is also the default. I have no reference point 
for what "fast" and "slow" mean in this context :)