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Commit ae779300 authored by Mel Gorman's avatar Mel Gorman Committed by Rafael J. Wysocki
Browse files

cpuidle: menu: Use shifts when calculating averages where possible 



We use do_div even though the divisor will usually be a power-of-two
unless there are unusual outliers. Use shifts where possible

Signed-off-by: default avatarMel Gorman <mgorman@suse.de>
Signed-off-by: default avatarRafael J. Wysocki <rafael.j.wysocki@intel.com>
parent dd38c9d3

drivers/cpuidle/governors/menu.c

+11 −3
Original line number Diff line number Diff line
@@ -31,7 +31,8 @@ 
 * The default values do not overflow.

 */

#define BUCKETS 12

#define INTERVALS 8

#define INTERVAL_SHIFT 3

#define INTERVALS (1UL << INTERVAL_SHIFT)

#define RESOLUTION 1024

#define DECAY 8

#define MAX_INTERESTING 50000
@@ -227,6 +228,9 @@ static void get_typical_interval(struct menu_device *data) 
				max = value;

		}

	}

	if (divisor == INTERVALS)

		avg >>= INTERVAL_SHIFT;

	else

		do_div(avg, divisor);



	/* Then try to determine standard deviation */
@@ -238,7 +242,11 @@ static void get_typical_interval(struct menu_device *data) 
			stddev += diff * diff;

		}

	}

	if (divisor == INTERVALS)

		stddev >>= INTERVAL_SHIFT;

	else

		do_div(stddev, divisor);



	/*

	 * The typical interval is obtained when standard deviation is small

	 * or standard deviation is small compared to the average interval.