From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org X-Spam-Level: X-Spam-Status: No, score=-3.8 required=3.0 tests=BAYES_00,DKIM_INVALID, DKIM_SIGNED,HEADER_FROM_DIFFERENT_DOMAINS,MAILING_LIST_MULTI,SPF_HELO_NONE, SPF_PASS,URIBL_BLOCKED autolearn=no autolearn_force=no version=3.4.0 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id D11C6C433DF for ; Fri, 7 Aug 2020 14:12:08 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id AE3CC22CA1 for ; Fri, 7 Aug 2020 14:12:08 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=fail reason="signature verification failed" (2048-bit key) header.d=infradead.org header.i=@infradead.org header.b="mr1fv8hg" Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1726076AbgHGOLw (ORCPT ); Fri, 7 Aug 2020 10:11:52 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:42684 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1725815AbgHGOLh (ORCPT ); Fri, 7 Aug 2020 10:11:37 -0400 Received: from merlin.infradead.org (merlin.infradead.org [IPv6:2001:8b0:10b:1231::1]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id AD47CC061756; Fri, 7 Aug 2020 07:11:36 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; q=dns/txt; c=relaxed/relaxed; d=infradead.org; s=merlin.20170209; h=In-Reply-To:Content-Type:MIME-Version: References:Message-ID:Subject:Cc:To:From:Date:Sender:Reply-To: Content-Transfer-Encoding:Content-ID:Content-Description; bh=3SeHm1ZjMHsIJfjxrX9fUGzdepcw8YyHP7a7yWdfxp8=; b=mr1fv8hgzT1vJ+/IBK5iw5aGKm mu7pn6wNwqMJAeone/Rv0P5Mr1Jty9gc3ALqnSGBRb4qujMQfeNAH62LUcV2dk8bFozf0uSc+mOqk PLe3pfK1GwBLk+NGReUkckLhk2IBQmbKiRRgd1XNi/7JEzm04sMvOPUIR73O+uDaWrezu2ZCegi3s YdaCNorJIt2DcIoZenrouHeKm2x+Q/oAXf1eac6x4fvJPDIgsBoRh9L/ApJJOIBbUBfLw69Mn9T+y 25K7O5ydz9jaq3kDW/wOEMs8bybEr47Jec07uCVH+Kr4Fyb30jcKBt6hZszVO8Z9zNJrAo6ZJoeuM GYVT2xzg==; Received: from j217100.upc-j.chello.nl ([24.132.217.100] helo=noisy.programming.kicks-ass.net) by merlin.infradead.org with esmtpsa (Exim 4.92.3 #3 (Red Hat Linux)) id 1k435d-00065v-Lq; Fri, 07 Aug 2020 14:11:21 +0000 Received: from hirez.programming.kicks-ass.net (hirez.programming.kicks-ass.net [192.168.1.225]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (Client did not present a certificate) by noisy.programming.kicks-ass.net (Postfix) with ESMTPS id EDFBC3012DC; Fri, 7 Aug 2020 16:11:18 +0200 (CEST) Received: by hirez.programming.kicks-ass.net (Postfix, from userid 1000) id AC91B21451927; Fri, 7 Aug 2020 16:11:18 +0200 (CEST) Date: Fri, 7 Aug 2020 16:11:18 +0200 From: peterz@infradead.org To: luca abeni Cc: Juri Lelli , mingo@redhat.com, rostedt@goodmis.org, tglx@linutronix.de, linux-kernel@vger.kernel.org, tommaso.cucinotta@santannapisa.it, alessio.balsini@gmail.com, bristot@redhat.com, dietmar.eggemann@arm.com, linux-rt-users@vger.kernel.org, mtosatti@redhat.com, williams@redhat.com, valentin.schneider@arm.com Subject: Re: [RFC PATCH v2 6/6] sched/fair: Implement starvation monitor Message-ID: <20200807141118.GK2674@hirez.programming.kicks-ass.net> References: <20200807095051.385985-1-juri.lelli@redhat.com> <20200807095604.GO42956@localhost.localdomain> <20200807104618.GH2674@hirez.programming.kicks-ass.net> <20200807154941.2bb11408@nowhere> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20200807154941.2bb11408@nowhere> Sender: linux-rt-users-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-rt-users@vger.kernel.org On Fri, Aug 07, 2020 at 03:49:41PM +0200, luca abeni wrote: > Hi Peter, > > peterz@infradead.org wrote: > > One thing I considerd was scheduling this as a least-laxity entity -- > > such that it runs late, not early > > Are you thinking about scheduling both RT and non-RT tasks through > deadline servers? If yes, Maybe, I initially considered this for mixed criticality, where the 'soft' class would run EDF and the 'hard' class would run LLF (or the other way around, I can't quite remember how I figured it). If you restrict the hard class to single CPU assignment (IOW the UP case) and ensure that u_llf + U_gedf/N < 1, it should just work out. But I shelved all that after I heard about that other balancer idea Danial was suppose to be working on ;-))) > then I think that using something like > laxity-based scheduling for the SCHED_OTHER server can be a good idea > (but then we need to understand how to combine deadline-based > scheduling with laxity-based scheduling, etc...) /me consults notes, EDZL is I think the closest thing there. > Or are you thinking about keeping the SCHED_OTHER server throttled > until its laxity is 0 (or until its laxity is lower than some small > value)? In this second case, the approach would work even if RT tasks > are not scheduled through a server (but I do not know which kind of > performance guarantee we could provide). That would certainly be sufficient for OTHER servers I think.