From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1753063Ab2GZVZs (ORCPT ); Thu, 26 Jul 2012 17:25:48 -0400 Received: from casper.infradead.org ([85.118.1.10]:40426 "EHLO casper.infradead.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752964Ab2GZVZq convert rfc822-to-8bit (ORCPT ); Thu, 26 Jul 2012 17:25:46 -0400 Message-ID: <1343337937.32120.20.camel@twins> Subject: Re: [ 028/108] sched/nohz: Rewrite and fix load-avg computation -- again From: Peter Zijlstra To: Ben Hutchings Cc: stable@vger.kernel.org, torvalds@linux-foundation.org, akpm@linux-foundation.org, alan@lxorguk.ukuu.org.uk, Ingo Molnar , LKML Date: Thu, 26 Jul 2012 23:25:37 +0200 In-Reply-To: <1343138818.5132.98.camel@deadeye.wl.decadent.org.uk> References: <20120723010655.768372060@decadent.org.uk> <1343138818.5132.98.camel@deadeye.wl.decadent.org.uk> Content-Type: text/plain; charset=US-ASCII Content-Transfer-Encoding: 7BIT X-Mailer: Evolution 3.2.2- Mime-Version: 1.0 Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Tue, 2012-07-24 at 15:06 +0100, Ben Hutchings wrote: > On Mon, 2012-07-23 at 02:07 +0100, Ben Hutchings wrote: > > 3.2-stable review patch. If anyone has any objections, please let me know. > > > > ------------------ > > > > From: Peter Zijlstra > > > > commit 5167e8d5417bf5c322a703d2927daec727ea40dd upstream. > > > > Thanks to Charles Wang for spotting the defects in the current code: > > > > - If we go idle during the sample window -- after sampling, we get a > > negative bias because we can negate our own sample. > > > > - If we wake up during the sample window we get a positive bias > > because we push the sample to a known active period. > > > > So rewrite the entire nohz load-avg muck once again, now adding > > copious documentation to the code. > [...] > > Based on , I think we also need: > > 556061b sched/nohz: Fix rq->cpu_load[] calculations > 5aaa0b7 sched/nohz: Fix rq->cpu_load calculations some more > > Does this ('sched/nohz: Rewrite and fix load-avg computation -- again') > depend in any way on those, or are they separate fixes? they might touch on a few entry points but the logic is separate. ->cpu_load[] is per-cpu weight tracking for the load-balancer.