Date: Mon, 29 Aug 2011 16:20:46 -0500 From: Adam Vande More <amvandemore@gmail.com> To: Brett Glass <brett@lariat.net> Cc: Bruce Cran <bruce@cran.org.uk>, questions@freebsd.org Subject: Re: Turn off hyperthreading on dual core Atom? Message-ID: <CA%2BtpaK04%2BLi60hHot6QH2z_9Uv%2BtyVQ4OgY7OQFZGNSMHbRLPw@mail.gmail.com> In-Reply-To: <201108292115.PAA21491@lariat.net> References: <201108291724.LAA18734@lariat.net> <4E5BEE9C.7080706@cran.org.uk> <201108292115.PAA21491@lariat.net>
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On Mon, Aug 29, 2011 at 4:15 PM, Brett Glass <brett@lariat.net> wrote > Alas, during a recent kernel build, I used the -j2 command line option in > "make" and watched as the scheduler repeatedly assigned two instances of cc > (the most CPU-intensive program) to the same core. > > During that process, I also watched CPU utilization in top(1). The peak was > 46% idle, which means that HTT appeared to be making at most a 4% > difference. (If the peak were 50% idle, HTT would be doing nothing at all, > because top(1) can't tell that there aren't really 4 CPUs.) > You can achieve definitive answers by timing several build runs of each setting and using ministat. -- Adam Vande More
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