Message-ID: <4DA6D85A.8000800@wildgooses.com>
Date: Thu, 14 Apr 2011 12:19:54 +0100
From: Ed W <lists@wildgooses.com>
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To: johnstul@us.ibm.com, linux-kernel@vger.kernel.org
Subject: Improved TSC calculation
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Hi, Thanks for the new stable TSC calculation commit
(08ec0c58fb8a05d3191d5cb6f5d6f81adb419798).

My situation is that I don't have a PM or HPET timer (x86 Alix board),
and my requirements are embedded type use, but with only intermittently
connected network/gps, so accurate timekeeping between reboots is
important.

I had been experimenting with extending the existing PIT timer routines
at boot, but I had the problem that it was taking 1s+ to get a very
stable calculation (which is undesirable for my requirements), however,
having spotted your commit it seems like a much more sensible solution.

Before I try and hack probably an (inadequate) solution myself, do you
have any thoughts on the best solution to extend your commit to non
PM/HEPT machine?  My initial thought was to repeatedly call
pit_calibrate_tsc() with an extended latch, looking for a stable
solution (ie refactor native_calibrate_tsc() ).  Is this workable?
Better ideas?

Thanks

Ed W
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