From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1755630AbcBCL3l (ORCPT ); Wed, 3 Feb 2016 06:29:41 -0500 Received: from foss.arm.com ([217.140.101.70]:33505 "EHLO foss.arm.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752839AbcBCL3i (ORCPT ); Wed, 3 Feb 2016 06:29:38 -0500 Date: Wed, 3 Feb 2016 11:30:19 +0000 From: Juri Lelli To: Luca Abeni Cc: Peter Zijlstra , linux-kernel@vger.kernel.org, Ingo Molnar Subject: Re: [RFC 8/8] Do not reclaim the whole CPU bandwidth Message-ID: <20160203113019.GT3947@e106622-lin> References: <1452785094-3086-1-git-send-email-luca.abeni@unitn.it> <1452785094-3086-9-git-send-email-luca.abeni@unitn.it> <20160114195904.GH6357@twins.programming.kicks-ass.net> <5698ABFD.1040704@unitn.it> <20160115085004.GE3421@worktop> <20160126135219.338e8ccb@utopia> <20160127144422.GS6357@twins.programming.kicks-ass.net> <20160202215310.43fef86b@luca-1225C> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20160202215310.43fef86b@luca-1225C> User-Agent: Mutt/1.5.21 (2010-09-15) Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Hi Luca, Peter, On 02/02/16 21:53, Luca Abeni wrote: > On Wed, 27 Jan 2016 15:44:22 +0100 > Peter Zijlstra wrote: > > > On Tue, Jan 26, 2016 at 01:52:19PM +0100, luca abeni wrote: > > > > > > The trouble is with interfaces. Once we expose them we're stuck > > > > with them. And from that POV I think an explicit SCHED_OTHER > > > > server (or a minimum budget for a slack time scheme) makes more > > > > sense. > > > > > I am trying to work on this. > > > Which kind of interface is better for this? Would adding something > > > like /proc/sys/kernel/sched_other_period_us > > > /proc/sys/kernel/sched_other_runtime_us > > > be ok? > > > > > > If this is ok, I'll add these two procfs files, and store > > > (sched_other_runtime / sched_other_period) << 20 in the runqueue > > > field which represents the unreclaimable utilization (implementing > > > hierarchical SCHED_DEADLINE/CFS scheduling right now is too complex > > > for this patchset... But if the exported interface is ok, it can be > > > implemented later). > > > > > > Is this approach acceptable? Or am I misunderstanding your comment? > > > > No, I think that's fine. > So, I implemented this idea (/proc/sys/kernel/sched_other_period_us > and /proc/sys/kernel/sched_other_runtime_us to set the unreclaimable > utilization), and some initial testing seems to show that it works fine. > Sorry for not saying this before, but why can't we use the existing sched_rt_runtime_us/sched_rt_runtime_period cap for this? I mean, other will have (1 - rt_runtime_ratio) available to run. Best, - Juri