From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S268327AbUH2Vdm (ORCPT ); Sun, 29 Aug 2004 17:33:42 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S268336AbUH2Vdm (ORCPT ); Sun, 29 Aug 2004 17:33:42 -0400 Received: from peabody.ximian.com ([130.57.169.10]:6829 "EHLO peabody.ximian.com") by vger.kernel.org with ESMTP id S268327AbUH2Vdk (ORCPT ); Sun, 29 Aug 2004 17:33:40 -0400 Subject: Re: interrupt cpu time accounting? From: Robert Love To: Jeff Garzik Cc: Linux Kernel , Ingo Molnar In-Reply-To: <413249F7.50904@pobox.com> References: <41323FA8.80203@pobox.com> <1093814102.2595.8.camel@localhost> <413249F7.50904@pobox.com> Content-Type: text/plain Date: Sun, 29 Aug 2004 17:33:40 -0400 Message-Id: <1093815220.2595.14.camel@localhost> Mime-Version: 1.0 X-Mailer: Evolution 1.5.93 (1.5.93-2) Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org X-Mailing-List: linux-kernel@vger.kernel.org On Sun, 2004-08-29 at 17:26 -0400, Jeff Garzik wrote: > What piece of code defines "balanced"? :) kernel/sched.c :: load_balance() We used to try to keep the processors within 25% of each other, and try very hard to ensure that no processor had zero processes. The sched domain code changed all that. The only place the load balancer will help in your scenario is when the processor is so busy processing interrupts and processes get backed up on the processor (new processes moved there or, more likely, via forks). The load balance won't help if the baseline minimum number of processes is there but they are starving. > Less a neat idea, and more IMHO recognition of a problem that needs solving. > > I am worried that processes will get starved if one CPU is _heavily_ > loaded servicing interrupts, and the others are not. If people are seeing it, then I 100% agree. Robert Love