To SMP or not to SMP

[Barney Cordoba]

--- On Tue, 1/8/13, Ian Smith <smithi at nimnet.asn.au> wrote:

> From: Ian Smith <smithi at nimnet.asn.au>
> Subject: Re: To SMP or not to SMP
> To: "Garrett Cooper" <yanegomi at gmail.com>
> Cc: "Barney Cordoba" <barney_cordoba at yahoo.com>, "Erich Dollansky" <erichsfreebsdlist at alogt.com>, freebsd-net at freebsd.org
> Date: Tuesday, January 8, 2013, 11:34 AM
> 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

I don't need no stinking graphs. I'll do some testing.

bc