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Date: 23 Jul 2011 18:13:04 +1000
Date: Sat, 23 Jul 2011 18:13:04 +1000
From: Callum Gibson <callumgibson@optusnet.com.au>
To: John Baldwin <jhb@freebsd.org>
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Cc: Attilio Rao <attilio@freebsd.org>, freebsd-stable@freebsd.org,
	Jung-uk Kim <jkim@freebsd.org>, freebsd-amd64@freebsd.org
Subject: Re: powernow regression in 8-STABLE
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On 22Jul11 08:16, John Baldwin wrote:
}The problem is that we calibrate the TSC using this algorithm:
}
} - grab the TSC
} - spin on the ISA timer waiting for it to run for a second
} - grab the TSC
}
}The issue is that the SMI# fires at the same time we want to be execuiting 
}step 3, and step 3 is deferred while the SMI# handler runs.  As a result, the 
}TSC delta ends up being "1 second + time of an SMI# to poll USB".  We have a 
}hack fix for this at work that originally came from Attilio Rao.  This is a 
}patch for it relative to 8.  It disables interrupt generation for the ISA 
}timer while we calibrate the TSC (which disables the SMI# temporarily):

Thanks, John. The hack works as intended, but I guess it's not a "real"
solution which is why you haven't committed it?

    C

-- 

Callum Gibson @ home
http://members.optusnet.com.au/callumgibson/