Date: Mon, 19 Nov 2007 08:19:11 -0500 From: Bill Moran <wmoran@potentialtech.com> To: Dinesh Nair <dinesh@alphaque.com> Cc: Manolis Kiagias <sonicy@otenet.gr>, freebsd-questions@freebsd.org, Wojciech Puchar <wojtek@wojtek.tensor.gdynia.pl> Subject: Re: hyperthreading CPU and broken scheduling? Message-ID: <20071119081911.5a147893.wmoran@potentialtech.com> In-Reply-To: <20071119115723.0701c02a@prophet.alphaque.com> References: <20071118111446.H4507@wojtek.tensor.gdynia.pl> <4740140C.6050103@otenet.gr> <20071119115723.0701c02a@prophet.alphaque.com>
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In response to Dinesh Nair <dinesh@alphaque.com>: > On Sun, 18 Nov 2007 12:29:32 +0200, Manolis Kiagias wrote: > > > Wojciech Puchar wrote: > > > i have machune with intel's CPU with hyperthreading. > > > > > > it is detected right, but only first thread is ever used. > > > > > > top shows at least 50% idle no matter what i run! > > > > > > what's wrong? > > To enable hyperthreading, try setting the following in /etc/sysctl.conf: > > > > machdep.hyperthreading_allowed=1 > > > > and reboot (or execute sysctl machdep.hyperthreading_allowed=1 by hand). > > would an SMP kernel be required to properly use hyperthreading, or would > just the above sysctl setting be enough ? The SMP kernel is required as well. -- Bill Moran http://www.potentialtech.com
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