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| author | Mel Gorman <mgorman@suse.de> | 2014-08-06 14:19:18 +0100 |
|---|---|---|
| committer | Rafael J. Wysocki <rafael.j.wysocki@intel.com> | 2014-08-06 21:17:44 +0200 |
| commit | ae77930060338226a4377d3b93580c43b5ec82ae (patch) | |
| tree | 161b93ae479de6e0cea6007e9b01819287cc82fc /drivers/cpuidle/governors | |
| parent | dd38c9d35ba8e40011b36659cae2719aefd11904 (diff) | |
| download | blackbird-op-linux-ae77930060338226a4377d3b93580c43b5ec82ae.tar.gz blackbird-op-linux-ae77930060338226a4377d3b93580c43b5ec82ae.zip | |
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: Mel Gorman <mgorman@suse.de>
Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
Diffstat (limited to 'drivers/cpuidle/governors')
| -rw-r--r-- | drivers/cpuidle/governors/menu.c | 14 |
1 files changed, 11 insertions, 3 deletions
diff --git a/drivers/cpuidle/governors/menu.c b/drivers/cpuidle/governors/menu.c index c3732fa74f82..c36e1ea7ef08 100644 --- a/drivers/cpuidle/governors/menu.c +++ b/drivers/cpuidle/governors/menu.c @@ -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 @@ -227,7 +228,10 @@ again: max = value; } } - do_div(avg, divisor); + if (divisor == INTERVALS) + avg >>= INTERVAL_SHIFT; + else + do_div(avg, divisor); /* Then try to determine standard deviation */ stddev = 0; @@ -238,7 +242,11 @@ again: stddev += diff * diff; } } - do_div(stddev, divisor); + 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. |
