intel_pstate: Correct rounding in busy calculation

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commit 51d211e9c3 upstream.

There was a mistake in the actual rounding portion this previous patch:
f0fe3cd7e1 (intel_pstate: Correct rounding in busy calculation) such that
the rounding was asymetric and incorrect.

Severity: Not very serious, but can increase target pstate by one extra value.
For real world work flows the issue should self correct (but I have no proof).
It is the equivalent of different PID gains for positive and negative numbers.

Examples:
 -3.000000 used to round to -4, rounds to -3 with this patch.
 -3.503906 used to round to -5, rounds to -4 with this patch.

Fixes: f0fe3cd7e1 (intel_pstate: Correct rounding in busy calculation)
Signed-off-by: Doug Smythies <dsmythies@telus.net>
Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

...

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Doug Smythies 2014-06-17 13:36:10 -07:00 • committed by Greg Kroah-Hartman

parent 3c022c3888

commit 5abec5508d

1 changed files with 1 additions and 4 deletions

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drivers/cpufreq/intel_pstate.c

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