Date: Sat, 23 Jul 2011 18:13:04 +1000 From: Callum Gibson <callumgibson@optusnet.com.au> To: John Baldwin <jhb@freebsd.org> Cc: Attilio Rao <attilio@freebsd.org>, freebsd-stable@freebsd.org, freebsd-amd64@freebsd.org Subject: Re: powernow regression in 8-STABLE Message-ID: <20110723081304.GA14172@omma.gibson.athome> In-Reply-To: <201107220816.52901.jhb@freebsd.org> References: <20110719112033.GA51765@omma.gibson.athome> <20110721205600.GA52261@omma.gibson.athome> <20110721214310.GA74656@icarus.home.lan> <201107220816.52901.jhb@freebsd.org>
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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/
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