summaryrefslogtreecommitdiff
path: root/include/linux/average.h
AgeCommit message (Collapse)AuthorFilesLines
2017-03-02average: change to declare precision, not factorJohannes Berg1-20/+41
Declaring the factor is counter-intuitive, and people are prone to using small(-ish) values even when that makes no sense. Change the DECLARE_EWMA() macro to take the fractional precision, in bits, rather than a factor, and update all users. While at it, add some more documentation. Acked-by: David S. Miller <davem@davemloft.net> Signed-off-by: Johannes Berg <johannes.berg@intel.com>
2015-08-21average: remove out-of-line implementationJohannes Berg1-24/+0
Since all users are now converted to the inline implementation, remove the out-of-line implementation entirely. Signed-off-by: Johannes Berg <johannes.berg@intel.com> Signed-off-by: David S. Miller <davem@davemloft.net>
2015-08-14average: provide macro to create static EWMAJohannes Berg1-0/+39
Having the EWMA parameters stored in the runtime struct imposes memory requirements for the constant values that could just be inlined in the code. This particularly makes sense if there are a lot of such structs, for example in mac80211 in the station table where each station has a number of these in an array, and there can be many stations. Provide a macro DECLARE_EWMA() that declares the necessary struct and inline functions to access it with the parameters hard-coded; using this also means the user no longer needs to 'select AVERAGE' as it's entirely self-contained. In the mac80211 case, on x86-64, this actually slightly *reduces* code size, while also saving 80 bytes of runtime memory per sta. Signed-off-by: Johannes Berg <johannes.berg@intel.com>
2010-12-06lib: Improve EWMA efficiency by using bitshiftsBruno Randolf1-3/+1
Using bitshifts instead of division and multiplication should improve performance. That requires weight and factor to be powers of two, but i think this is something we can live with. Thanks to Peter Zijlstra for the improved formula! Signed-off-by: Bruno Randolf <br1@einfach.org> -- v2: use log2.h functions Signed-off-by: John W. Linville <linville@tuxdriver.com>
2010-11-18lib: Add generic exponentially weighted moving average (EWMA) functionBruno Randolf1-0/+32
This adds generic functions for calculating Exponentially Weighted Moving Averages (EWMA). This implementation makes use of a structure which keeps the EWMA parameters and a scaled up internal representation to reduce rounding errors. The original idea for this implementation came from the rt2x00 driver (rt2x00link.c). I would like to use it in several places in the mac80211 and ath5k code and I hope it can be useful in many other places in the kernel code. Signed-off-by: Bruno Randolf <br1@einfach.org> Reviewed-by: KOSAKI Motohiro <kosaki.motohiro@jp.fujitsu.com> Signed-off-by: John W. Linville <linville@tuxdriver.com>