Return-path: Received: from he.sipsolutions.net ([78.46.109.217]:42074 "EHLO sipsolutions.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1757760Ab3CDPGW (ORCPT ); Mon, 4 Mar 2013 10:06:22 -0500 Message-ID: <1362409577.21028.13.camel@jlt4.sipsolutions.net> (sfid-20130304_160626_279352_8FFD67E4) Subject: Re: [PATCH 1/3] minstrel_ht: improve accuracy of throughput metric at high data rates From: Johannes Berg To: Felix Fietkau Cc: linux-wireless@vger.kernel.org Date: Mon, 04 Mar 2013 16:06:17 +0100 In-Reply-To: <1362255614-30859-1-git-send-email-nbd@openwrt.org> References: <1362255614-30859-1-git-send-email-nbd@openwrt.org> Content-Type: text/plain; charset="UTF-8" Mime-Version: 1.0 Sender: linux-wireless-owner@vger.kernel.org List-ID: On Sat, 2013-03-02 at 21:20 +0100, Felix Fietkau wrote: > At high data rates the average frame transmission durations are small > enough for rounding errors to matter, sometimes causing minstrel to use > slightly lower transmit rates than necessary. > To fix this, change the unit of the duration value to nanoseconds > instead of microseconds, and reorder the multiplications/divisions when > calculating the throughput metric so that they don't overflow or > truncate prematurely. > At 2-stream HT40 this makes TCP throughput a bit more stable. Applied all 3. johannes