Messages in this thread | | | From | Bruno Randolf <> | Subject | Re: [PATCH v7 3/3] nl80211/mac80211: Report signal average | Date | Fri, 19 Nov 2010 18:07:05 +0900 |
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On Thu November 18 2010 08:11:18 Bob Copeland wrote: > On Wed, Nov 17, 2010 at 11:16 AM, Johannes Berg > > <johannes@sipsolutions.net> wrote: > > On Wed, 2010-11-17 at 17:28 +0900, Bruno Randolf wrote: > >> I understand that this could be more efficient, but if it matters or not > >> - honestly, I don't know. Can a more knowledgeable person than me > >> comment on this? > > > > Yes, it does matter -- think of an embedded MIPS board running at 500MHz > > and trying to push 11n speeds. > > I assume the number of samples (weight) is the more > important tunable. One option is you can require factor > to be a power of two that is much larger than weight, > then at least you can store factor/weight precomputed > and multiply by it instead of doing a divide in ewma_add. > Then ewma_get can also just be a shift as well.
Hmm, maybe I suck in mathemathics, but I don't see a way to do that given the formula:
(((internal * (weight - 1)) + (val * factor)) / weight
bruno
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