Disable pristine-tar option in gbp.conf, since there is no pristine-tar branch.

[bcachefs-tools-debian] / linux / mean_and_variance.c

diff --git a/linux/mean_and_variance.c b/linux/mean_and_variance.c
index eb5f2ba03b7fbdd920b0080600989a0dc76f8e61..21ec6afc6788413a35c815cef827ef8a25891329 100644 (file)
--- a/linux/mean_and_variance.c
+++ b/linux/mean_and_variance.c
@@ -61,6 +61,7 @@ EXPORT_SYMBOL_GPL(u128_div);
 
 /**
  * mean_and_variance_get_mean() - get mean from @s
+ * @s: mean and variance number of samples and their sums
  */
 s64 mean_and_variance_get_mean(struct mean_and_variance s)
 {
@@ -70,6 +71,7 @@ EXPORT_SYMBOL_GPL(mean_and_variance_get_mean);
 
 /**
  * mean_and_variance_get_variance() -  get variance from @s1
+ * @s1: mean and variance number of samples and sums
  *
  * see linked pdf equation 12.
  */
@@ -88,6 +90,7 @@ EXPORT_SYMBOL_GPL(mean_and_variance_get_variance);
 
 /**
  * mean_and_variance_get_stddev() - get standard deviation from @s
+ * @s: mean and variance number of samples and their sums
  */
 u32 mean_and_variance_get_stddev(struct mean_and_variance s)
 {
@@ -97,16 +100,19 @@ EXPORT_SYMBOL_GPL(mean_and_variance_get_stddev);
 
 /**
  * mean_and_variance_weighted_update() - exponentially weighted variant of mean_and_variance_update()
- * @s1: ..
- * @s2: ..
+ * @s: mean and variance number of samples and their sums
+ * @x: new value to include in the &mean_and_variance_weighted
+ * @initted: caller must track whether this is the first use or not
+ * @weight: ewma weight
  *
  * see linked pdf: function derived from equations 140-143 where alpha = 2^w.
  * values are stored bitshifted for performance and added precision.
  */
-void mean_and_variance_weighted_update(struct mean_and_variance_weighted *s, s64 x)
+void mean_and_variance_weighted_update(struct mean_and_variance_weighted *s,
+               s64 x, bool initted, u8 weight)
 {
        // previous weighted variance.
-       u8 w            = s->weight;
+       u8 w            = weight;
        u64 var_w0      = s->variance;
        // new value weighted.
        s64 x_w         = x << w;
@@ -115,42 +121,50 @@ void mean_and_variance_weighted_update(struct mean_and_variance_weighted *s, s64
        // new mean weighted.
        s64 u_w1        = s->mean + diff;
 
-       if (!s->init) {
+       if (!initted) {
                s->mean = x_w;
                s->variance = 0;
        } else {
                s->mean = u_w1;
                s->variance = ((var_w0 << w) - var_w0 + ((diff_w * (x_w - u_w1)) >> w)) >> w;
        }
-       s->init = true;
 }
 EXPORT_SYMBOL_GPL(mean_and_variance_weighted_update);
 
 /**
  * mean_and_variance_weighted_get_mean() - get mean from @s
+ * @s: mean and variance number of samples and their sums
+ * @weight: ewma weight
  */
-s64 mean_and_variance_weighted_get_mean(struct mean_and_variance_weighted s)
+s64 mean_and_variance_weighted_get_mean(struct mean_and_variance_weighted s,
+               u8 weight)
 {
-       return fast_divpow2(s.mean, s.weight);
+       return fast_divpow2(s.mean, weight);
 }
 EXPORT_SYMBOL_GPL(mean_and_variance_weighted_get_mean);
 
 /**
  * mean_and_variance_weighted_get_variance() -- get variance from @s
+ * @s: mean and variance number of samples and their sums
+ * @weight: ewma weight
  */
-u64 mean_and_variance_weighted_get_variance(struct mean_and_variance_weighted s)
+u64 mean_and_variance_weighted_get_variance(struct mean_and_variance_weighted s,
+               u8 weight)
 {
        // always positive don't need fast divpow2
-       return s.variance >> s.weight;
+       return s.variance >> weight;
 }
 EXPORT_SYMBOL_GPL(mean_and_variance_weighted_get_variance);
 
 /**
  * mean_and_variance_weighted_get_stddev() - get standard deviation from @s
+ * @s: mean and variance number of samples and their sums
+ * @weight: ewma weight
  */
-u32 mean_and_variance_weighted_get_stddev(struct mean_and_variance_weighted s)
+u32 mean_and_variance_weighted_get_stddev(struct mean_and_variance_weighted s,
+               u8 weight)
 {
-       return int_sqrt64(mean_and_variance_weighted_get_variance(s));
+       return int_sqrt64(mean_and_variance_weighted_get_variance(s, weight));
 }
 EXPORT_SYMBOL_GPL(mean_and_variance_weighted_get_stddev);