Timer setting in FreeBSD

[Jason Henson]

On 03/10/05 21:24:03, Anthony Atkielski wrote:
> I was reading that recent versions of Linux have increased the base
> timer rate (for scheduling and other purposes) from 100 Hz to 1000  
> Hz.
> I note that FreeBSD apparently will increase this in the same way in
> 6.x.
> 
> Is there a way to adjust this value (by configuration, modifying
> source,
> sysctl, etc.)?  Can it be done on a running system?  If it can be
> changed, are there any significant reasons for adjusting it, and what
> are the pros and cons?
> 
> Having 1000 interrupts per second just to keep track of the time  
> seems
> excessive to me in most configurations.  Does anyone know how long
> this
> interrupt takes to service under FreeBSD with specific processors?
> 
> --
> Anthony
> 
> 
> _______________________________________________

man polling, this is what I use to get the best possible even division  
with the "Timecounter "i8254" frequency 1193182 Hz quality 0".

add something like this to the kernel config.
options         HZ=2299
options         DEVICE_POLLING

Also you should search the archives first, there is plenty of info on  
this there.  Things like 10000 is a good setting for gigbit ethernet  
cards, and not needed at all with some network cards that have some  
hardware/driver combonation that does this automatically.  I think the  
fxp cards do it, and adding polling to fxp cards hurt performance  
alittle.