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Date: Tue, 23 Dec 2008 10:05:08 -0500
To: Pieter de Goeje <pieter@degoeje.nl>, freebsd-performance@freebsd.org
From: Mike Tancsa <mike@sentex.net>
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	<giqce6$69o$1@ger.gmane.org> <200812231122.02892.pieter@degoeje.nl>
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Cc: Ivan Voras <ivoras@freebsd.org>
Subject: Re: intel i7 and Hyperthreading
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At 05:22 AM 12/23/2008, Pieter de Goeje wrote:
>On Tuesday 23 December 2008, Ivan Voras wrote:
> > Mike Tancsa wrote:
> > > Just got our first board to play around with and unlike in the past,
> > > having hyperthreading enabled seems to help performance.... At least in
> > > buildworld tests.
> > >
> > > doing a make -j4 vs -j6 make -j8 vs -j10 gives
> > >
> > > -j  buildworld time    % improvement over -j4
> > > 4       13:57
> > > 6       12:11            13%
> > > 8       11:32            18%
> > > 10      11:43            17%
> >
> > Thanks for posting this!
>
>What's missing is build times with hyperthreading disabled.
>make buildworld -j10 could easily be faster than -j4 even when hyperthreading
>is disabled, because of increased disk I/O concurrency.
>
>11:43 to build world is very fast indeed :-)

With HT disabled in the BIOS

make -j4, 13:48
make -j8, 12:35

so -j4 is about the same, but -j8 does show a bit of an improvement 
with HT enabled ( ~9%) ...

         ---Mike