Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1755446AbaBUOZM (ORCPT ); Fri, 21 Feb 2014 09:25:12 -0500 Received: from forward5m.mail.yandex.net ([37.140.138.5]:52034 "EHLO forward5m.mail.yandex.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1755151AbaBUOZK (ORCPT ); Fri, 21 Feb 2014 09:25:10 -0500 From: Kirill Tkhai To: Juri Lelli Cc: Peter Zijlstra , "linux-kernel@vger.kernel.org" , Steven Rostedt , Ingo Molnar In-Reply-To: <20140221134438.ab2d02c4165fa2a6cbd663be@gmail.com> References: <230991392848160@web13m.yandex.ru> <20140221103715.GP9987@twins.programming.kicks-ass.net> <128831392982418@web15j.yandex.ru> <311621392984565@web3h.yandex.ru> <20140221134438.ab2d02c4165fa2a6cbd663be@gmail.com> Subject: Re: [RFC] sched/deadline: Prevent rt_time growth to infinity MIME-Version: 1.0 Message-Id: <3231392992702@web26m.yandex.ru> X-Mailer: Yamail [ http://yandex.ru ] 5.0 Date: Fri, 21 Feb 2014 18:25:02 +0400 Content-Transfer-Encoding: 8bit Content-Type: text/plain; charset=koi8-r Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org 21.02.2014, 16:44, "Juri Lelli" : > On Fri, 21 Feb 2014 16:09:25 +0400 > Kirill Tkhai wrote: > >> ?21.02.2014, 15:39, "Kirill Tkhai" : >>> ?21.02.2014, 14:37, "Peter Zijlstra" : >>>> ??On Thu, Feb 20, 2014 at 02:16:00AM +0400, Kirill Tkhai wrote: >>>>> ???Since deadline tasks share rt bandwidth, we must care about >>>>> ???bandwidth timer set. Otherwise rt_time may grow up to infinity >>>>> ???in update_curr_dl(), if there are no other available RT tasks >>>>> ???on top level bandwidth. >>>>> >>>>> ???I'm going to decide the problem the way below. Almost untested >>>>> ???because of I skipped almost all of recent patches which haveto be applied from lkml. >>>>> >>>>> ???Please say, if I skipped anything in idea. Maybe better put >>>>> ???start_top_rt_bandwidth() into set_curr_task_dl()? >>>> ??How about we only increment rt_time when there's an RT bandwidth timer >>>> ??active? >>> ?This case RT and DL may eat all the time: >>> >>> ?-------------- ?time ------------------> >>> ?|RT's working |DL's working| >>> ?---------------------------- >>> ?|rt_runtime ??| ???????????| >>> ?---------------------------- >>> ?| ???????rt_period ????????| >>> >>> ?Or at least more, than it's allowed. >>> >>> ?It looks like, if we want to limit time of high priority classes >>> ?execution, we have to set the timer anyway. >> ?Oh, above is confusing. Sorry. >> >> ?I mean one RT task and >> >> ?----------------- ?time --------------------------> >> ?|DL's working ???|RT's working| |DL's working ???| >> ?-------------------------------------------------- >> ?| ???????????????|rt_runtime ?| | ???????????????| >> ?-------------------------------------------------- >> ?| ???????????????| ??rt_period ?| ???????????????| >> >> ?In this case FAIR receives less ratio, than (rt_period-rt_runtime)/rt_period. > > DL tasks won't be allowed to run in this situation, as their bw exceedes > rt_runtime/rt_period. Maybe, I don't uderstand. Where does DL control summary (DL+RT) runtime? RT does not do this too. But it looks like, RT has to do this. Kirill -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/