From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1756749AbcANT7K (ORCPT ); Thu, 14 Jan 2016 14:59:10 -0500 Received: from bombadil.infradead.org ([198.137.202.9]:57598 "EHLO bombadil.infradead.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1753205AbcANT7I (ORCPT ); Thu, 14 Jan 2016 14:59:08 -0500 Date: Thu, 14 Jan 2016 20:59:04 +0100 From: Peter Zijlstra To: Luca Abeni Cc: linux-kernel@vger.kernel.org, Ingo Molnar , Juri Lelli Subject: Re: [RFC 8/8] Do not reclaim the whole CPU bandwidth Message-ID: <20160114195904.GH6357@twins.programming.kicks-ass.net> References: <1452785094-3086-1-git-send-email-luca.abeni@unitn.it> <1452785094-3086-9-git-send-email-luca.abeni@unitn.it> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <1452785094-3086-9-git-send-email-luca.abeni@unitn.it> 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, Jan 14, 2016 at 04:24:53PM +0100, Luca Abeni wrote: > Original GRUB tends to reclaim 100% of the CPU time... And this allows a > "CPU hog" (i.e., a busy loop) to starve non-deadline tasks. > To address this issue, allow the scheduler to reclaim only a specified > fraction of CPU time. > NOTE: the fraction of CPU time that cannot be reclaimed is currently > hardcoded as (1 << 20) / 10 -> 90%, but it must be made configurable! So the alternative is an explicit SCHED_OTHER server which is configurable. That would maybe fit in nicely with the DL based FIFO/RR servers from this other pending project. > --- a/kernel/sched/sched.h > +++ b/kernel/sched/sched.h > @@ -524,6 +524,10 @@ struct dl_rq { > * and decreased when a task blocks > */ > s64 running_bw; > + /* This is the amount of utilization that GRUB can not > + * reclaim (per runqueue) > + */ > + s64 unusable_bw; Wrong comment style and whitespace challenged.