diff options
Diffstat (limited to 'fs/gfs2/lock_dlm.c')
| -rw-r--r-- | fs/gfs2/lock_dlm.c | 37 |
1 files changed, 20 insertions, 17 deletions
diff --git a/fs/gfs2/lock_dlm.c b/fs/gfs2/lock_dlm.c index 153272f82984..dac040162ecc 100644 --- a/fs/gfs2/lock_dlm.c +++ b/fs/gfs2/lock_dlm.c @@ -24,28 +24,31 @@ /** * gfs2_update_stats - Update time based stats - * @mv: Pointer to mean/variance structure to update + * @s: The stats to update (local or global) + * @index: The index inside @s * @sample: New data to include - * - * @delta is the difference between the current rtt sample and the - * running average srtt. We add 1/8 of that to the srtt in order to - * update the current srtt estimate. The variance estimate is a bit - * more complicated. We subtract the current variance estimate from - * the abs value of the @delta and add 1/4 of that to the running - * total. That's equivalent to 3/4 of the current variance - * estimate plus 1/4 of the abs of @delta. - * - * Note that the index points at the array entry containing the smoothed - * mean value, and the variance is always in the following entry - * - * Reference: TCP/IP Illustrated, vol 2, p. 831,832 - * All times are in units of integer nanoseconds. Unlike the TCP/IP case, - * they are not scaled fixed point. */ - static inline void gfs2_update_stats(struct gfs2_lkstats *s, unsigned index, s64 sample) { + /* + * @delta is the difference between the current rtt sample and the + * running average srtt. We add 1/8 of that to the srtt in order to + * update the current srtt estimate. The variance estimate is a bit + * more complicated. We subtract the current variance estimate from + * the abs value of the @delta and add 1/4 of that to the running + * total. That's equivalent to 3/4 of the current variance + * estimate plus 1/4 of the abs of @delta. + * + * Note that the index points at the array entry containing the + * smoothed mean value, and the variance is always in the following + * entry + * + * Reference: TCP/IP Illustrated, vol 2, p. 831,832 + * All times are in units of integer nanoseconds. Unlike the TCP/IP + * case, they are not scaled fixed point. + */ + s64 delta = sample - s->stats[index]; s->stats[index] += (delta >> 3); index++; |