From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1753876AbbCFJHu (ORCPT ); Fri, 6 Mar 2015 04:07:50 -0500 Received: from casper.infradead.org ([85.118.1.10]:44031 "EHLO casper.infradead.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1750785AbbCFJHi (ORCPT ); Fri, 6 Mar 2015 04:07:38 -0500 Date: Fri, 6 Mar 2015 10:07:31 +0100 From: Peter Zijlstra To: David Ahern Cc: Mike Galbraith , Ingo Molnar , LKML Subject: Re: NMI watchdog triggering during load_balance Message-ID: <20150306090731.GY21418@twins.programming.kicks-ass.net> References: <54F92788.6010007@oracle.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <54F92788.6010007@oracle.com> User-Agent: Mutt/1.5.21 (2012-12-30) Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Thu, Mar 05, 2015 at 09:05:28PM -0700, David Ahern wrote: > Since each domain is a superset of the lower one each pass through > load_balance regularly repeats the processing of the previous domain (e.g., > NODE domain repeats the cpus in the CPU domain). Then multiplying that > across 1024 cpus and it seems like a of duplication. It is, _but_ each domain has an interval, bigger domains _should_ load balance at a bigger interval (iow lower frequency), and all this is lockless data gathering, so reusing stuff from the previous round could be quite stale indeed.