intel_pstate: Improve accuracy by not truncating until final result

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This patch addresses Bug 60727
(https://bugzilla.kernel.org/show_bug.cgi?id=60727)
which was due to the truncation of intermediate values in the
calculations, which causes the code to consistently underestimate the
current cpu frequency, specifically 100% cpu utilization was truncated
down to the setpoint of 97%. This patch fixes the problem by keeping
the results of all intermediate calculations as fixed point numbers
rather scaling them back and forth between integers and fixed point.

References: https://bugzilla.kernel.org/show_bug.cgi?id=60727
Signed-off-by: Brennan Shacklett <bpshacklett@gmail.com>
Acked-by: Dirk Brandewie <dirk.j.brandewie@intel.com>
Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>

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Brennan Shacklett 2013-10-21 09:20:32 -07:00 • committed by Rafael J. Wysocki

parent 31d141e3a6

commit d253d2a526

1 changed files with 15 additions and 18 deletions

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drivers/cpufreq/intel_pstate.c

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