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Date: Fri, 22 Oct 2004 10:24:31 -0600
From: Scott Long <scottl@freebsd.org>
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To: Mike Tancsa <mike@sentex.net>
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cc: freebsd-current@freebsd.org
Subject: Re: device apic on a single processor machine
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Mike Tancsa wrote:
> 
> When moving from RELENG_4 to RELENG_5, I noticed that in GENERIC, the 
> options
> 
> options         SMP             # Symmetric MultiProcessor Kernel
> device          apic            # I/O APIC
> 
> are enabled by default.  Going forward, is this the best thing to leave 
> in my  default kernel on a uniprocessor machine ? I am not using the ULE 
> scheduler either and have hyperthreading disabled in the BIOS.
> 
> I did a search on google, and in 2003 it was said not to having either 
> on a single processor machine but its not clear if this is no longer the 
> case.
> 
> 
>         ---Mike
> 

It's actually advisable to take both if you don't need them.  They are
they so that we will work on SMP by default, but do indeed affect 
performance.  Hopefully 5.4 will have some infrastructure in place to
provide both UP and SMP kernels to sysinstall.

Scott