Return-path: Received: from mail-qy0-f181.google.com ([209.85.216.181]:59038 "EHLO mail-qy0-f181.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S935559Ab0KQXLT (ORCPT ); Wed, 17 Nov 2010 18:11:19 -0500 MIME-Version: 1.0 In-Reply-To: <1290010595.3777.0.camel@jlt3.sipsolutions.net> References: <20101112024901.28522.21895.stgit@localhost6.localdomain6> <20101112030035.28522.75318.stgit@localhost6.localdomain6> <20101116093743.GA21872@jm.kir.nu> <201011171728.06801.br1@einfach.org> <1290010595.3777.0.camel@jlt3.sipsolutions.net> Date: Wed, 17 Nov 2010 18:11:18 -0500 Message-ID: Subject: Re: [PATCH v7 3/3] nl80211/mac80211: Report signal average From: Bob Copeland To: Bruno Randolf Cc: Johannes Berg , Jouni Malinen , linville@tuxdriver.com, randy.dunlap@oracle.com, peterz@infradead.org, blp@cs.stanford.edu, linux-wireless@vger.kernel.org, linux-kernel@vger.kernel.org, Lars_Ericsson@telia.com, stefanr@s5r6.in-berlin.de, kosaki.motohiro@jp.fujitsu.com, akpm@linux-foundation.org, kevin.granade@gmail.com Content-Type: text/plain; charset=ISO-8859-1 Sender: linux-wireless-owner@vger.kernel.org List-ID: On Wed, Nov 17, 2010 at 11:16 AM, Johannes Berg 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. -- Bob Copeland %% www.bobcopeland.com