diff options
author | John W. Linville <linville@tuxdriver.com> | 2010-12-13 15:20:45 -0500 |
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committer | John W. Linville <linville@tuxdriver.com> | 2010-12-13 15:20:45 -0500 |
commit | 1d212aa96e1b63459486f729af9a3fa38768b801 (patch) | |
tree | e91e74db57a5bb7884b4681cdb788d405ec8f10f /lib | |
parent | 8c4877a4128e7931077b024a891a4b284d8756a3 (diff) | |
parent | b7613370db5ba66ad81e41cd3a5417fde4d5e03c (diff) |
Merge branch 'master' of git://git.kernel.org/pub/scm/linux/kernel/git/linville/wireless-next-2.6 into for-davem
Diffstat (limited to 'lib')
-rw-r--r-- | lib/average.c | 20 |
1 files changed, 12 insertions, 8 deletions
diff --git a/lib/average.c b/lib/average.c index f1d1b4660c42..5576c2841496 100644 --- a/lib/average.c +++ b/lib/average.c | |||
@@ -8,6 +8,7 @@ | |||
8 | #include <linux/module.h> | 8 | #include <linux/module.h> |
9 | #include <linux/average.h> | 9 | #include <linux/average.h> |
10 | #include <linux/bug.h> | 10 | #include <linux/bug.h> |
11 | #include <linux/log2.h> | ||
11 | 12 | ||
12 | /** | 13 | /** |
13 | * DOC: Exponentially Weighted Moving Average (EWMA) | 14 | * DOC: Exponentially Weighted Moving Average (EWMA) |
@@ -24,18 +25,21 @@ | |||
24 | * ewma_init() - Initialize EWMA parameters | 25 | * ewma_init() - Initialize EWMA parameters |
25 | * @avg: Average structure | 26 | * @avg: Average structure |
26 | * @factor: Factor to use for the scaled up internal value. The maximum value | 27 | * @factor: Factor to use for the scaled up internal value. The maximum value |
27 | * of averages can be ULONG_MAX/(factor*weight). | 28 | * of averages can be ULONG_MAX/(factor*weight). For performance reasons |
29 | * factor has to be a power of 2. | ||
28 | * @weight: Exponential weight, or decay rate. This defines how fast the | 30 | * @weight: Exponential weight, or decay rate. This defines how fast the |
29 | * influence of older values decreases. Has to be bigger than 1. | 31 | * influence of older values decreases. For performance reasons weight has |
32 | * to be a power of 2. | ||
30 | * | 33 | * |
31 | * Initialize the EWMA parameters for a given struct ewma @avg. | 34 | * Initialize the EWMA parameters for a given struct ewma @avg. |
32 | */ | 35 | */ |
33 | void ewma_init(struct ewma *avg, unsigned long factor, unsigned long weight) | 36 | void ewma_init(struct ewma *avg, unsigned long factor, unsigned long weight) |
34 | { | 37 | { |
35 | WARN_ON(weight <= 1 || factor == 0); | 38 | WARN_ON(!is_power_of_2(weight) || !is_power_of_2(factor)); |
39 | |||
40 | avg->weight = ilog2(weight); | ||
41 | avg->factor = ilog2(factor); | ||
36 | avg->internal = 0; | 42 | avg->internal = 0; |
37 | avg->weight = weight; | ||
38 | avg->factor = factor; | ||
39 | } | 43 | } |
40 | EXPORT_SYMBOL(ewma_init); | 44 | EXPORT_SYMBOL(ewma_init); |
41 | 45 | ||
@@ -49,9 +53,9 @@ EXPORT_SYMBOL(ewma_init); | |||
49 | struct ewma *ewma_add(struct ewma *avg, unsigned long val) | 53 | struct ewma *ewma_add(struct ewma *avg, unsigned long val) |
50 | { | 54 | { |
51 | avg->internal = avg->internal ? | 55 | avg->internal = avg->internal ? |
52 | (((avg->internal * (avg->weight - 1)) + | 56 | (((avg->internal << avg->weight) - avg->internal) + |
53 | (val * avg->factor)) / avg->weight) : | 57 | (val << avg->factor)) >> avg->weight : |
54 | (val * avg->factor); | 58 | (val << avg->factor); |
55 | return avg; | 59 | return avg; |
56 | } | 60 | } |
57 | EXPORT_SYMBOL(ewma_add); | 61 | EXPORT_SYMBOL(ewma_add); |