To SMP or not to SMP

[Ian Smith]

On Tue, 8 Jan 2013 07:57:04 -0800, Garrett Cooper wrote:
 > On Jan 8, 2013, at 7:50 AM, Barney Cordoba wrote:
 > 
 > > --- On Mon, 1/7/13, Erich Dollansky <erichsfreebsdlist at alogt.com> wrote:
 > > 
 > >> From: Erich Dollansky <erichsfreebsdlist at alogt.com>
 > >> Subject: Re: To SMP or not to SMP
 > >> To: "Barney Cordoba" <barney_cordoba at yahoo.com>
 > >> Cc: freebsd-net at freebsd.org
 > >> Date: Monday, January 7, 2013, 10:56 PM
 > >> Hi,
 > >> 
 > >> On Mon, 7 Jan 2013 18:25:58 -0800 (PST)
 > >> Barney Cordoba <barney_cordoba at yahoo.com>
 > >> wrote:
 > >> 
 > >>> I have a situation where I have to run 9.1 on an old
 > >> single core box.
 > >>> Does anyone have a handle on whether it's better to
 > >> build a non SMP
 > >>> kernel or to just use a standard SMP build with just
 > >> the one core?
 > >>> Thanks.
 > >> 
 > >> I ran a single CPU version of FreeBSD until my last single
 > >> CPU got hit
 > >> by a lightning last April or May without any problems.
 > >> 
 > >> I never saw a reason to include the overhead of SMP for this
 > >> kind of
 > >> machine and I also never ran into problems with this.
 > > 
 > > Another "ass"umption based on logic rather than empirical evidence.
 > 
 > 	It isn't really an offhanded assumption because there _is_ 
 > additional overhead added into the kernel structures to make things 
 > work SMP with locking :). Whether or not it's measurable for you and 
 > your applications, I have no idea.
 > HTH,
 > -Garrett

Where's Kris Kennaway when you need something compared, benchmarked 
under N different types of loads, and nicely graphed?  Do we have a 
contender? :)

cheers, Ian