Re: HyperThreading

["Justin C. Sherrill" <justin@xxxxxxxxxxxxxxxxxx>]

On Thu, February 17, 2011 1:31 pm, Saman Barghi wrote:
> Since I moved from FreeBSD I make assumptions, I thought it is enabled by
> default which seems not to be case. I will build a custom kernel then (or
> is there a better way !? ) But my question is, why UP is proffered
> over SMP ?!
> is there any specific reason !? Does DFBSD perform better in UP rather
> than SMP mode ?! I just read that UP is the default mode forever (
> http://www.shiningsilence.com/dbsdlog/2010/10/26/6670.html), it is
> interesting to know the reason though.

Just to clarify, it's not that it _will be_ UP forever, it's just that it
always has been.  A UP kernel will run in environments where a SMP kernel
may have trouble - bad/wierd mptable, whatever, so this is playing it
safe.

If you boot a DragonFly CD/DVD, you have an option there of booting with a
SMP kernel.  If you install from there, you should also have a SMP kernel
installed.  If there's not too much on your DragonFly install, you could
always completely reinstall.  Otherwise, yes, rebuild the kernel.