From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1751276Ab2I3LoS (ORCPT ); Sun, 30 Sep 2012 07:44:18 -0400 Received: from smtp.getmail.no ([84.208.15.66]:44322 "EHLO smtp.getmail.no" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1750786Ab2I3LoR (ORCPT ); Sun, 30 Sep 2012 07:44:17 -0400 MIME-version: 1.0 Content-transfer-encoding: 7BIT Content-type: text/plain; charset=iso-8859-15; format=flowed; delsp=yes To: linux-kernel@vger.kernel.org Subject: The 10ms averager in fair.c Date: Sun, 30 Sep 2012 13:44:14 +0200 From: Uwaysi Bin Kareem Message-id: User-Agent: Opera Mail/11.10 (Linux) Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Hiya. I just had an initial look at fair.c There seems to be a 10ms averager in there? You are aware that that means you work on delayed values? Isn`t that counterintuitive to the principle of sharing? That means short bursts of cpu-use will be filtered out, and given less cpu time. Starting applications won`t have their cpu-usage before 5ms, which is quite a bit on modern machines. Well if you use a linearphase filter, I don`t know what kind of averager you use. The best would ofcourse be to use a minimalphase gaussian averager. Which might be overkill. Atleast a one-pole iir, buf = buf + (-buf + in) * cut)); One pole IIRs also have a better frequency response. When you are working with low-latencies, wouldn`t it be better if such things are tuned for target latency. I think few care about latency after 0.2ms. So say the filter should be set to 0.4ms max. Why would you want to filter cpu-usage also really? Peace Be With You. (please CC me.)