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=-3.9 required=3.0 tests=BAYES_00,DKIM_SIGNED, DKIM_VALID,DKIM_VALID_AU,HEADER_FROM_DIFFERENT_DOMAINS,MAILING_LIST_MULTI, SPF_HELO_NONE,SPF_PASS 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 00C4AC433E7 for ; Mon, 12 Oct 2020 13:18:35 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 7FF6A20714 for ; Mon, 12 Oct 2020 13:18:34 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (2048-bit key) header.d=infradead.org header.i=@infradead.org header.b="otYCoNU8" Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S2388856AbgJLNSe (ORCPT ); Mon, 12 Oct 2020 09:18:34 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:55890 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S2388160AbgJLNSd (ORCPT ); Mon, 12 Oct 2020 09:18:33 -0400 Received: from merlin.infradead.org (merlin.infradead.org [IPv6:2001:8b0:10b:1231::1]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id B36A4C0613D0 for ; Mon, 12 Oct 2020 06:18:32 -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=Hq040/XyURZ/o35rdIX1Xf3tR4gho9qLt4e+CVUXi6s=; b=otYCoNU8KVVZR99rDkPv3IQcSQ am99wN1F4yjO6dNH4cNhzAzbGPeUwftB+ICE11bEW7i64rAPg1gZ4bPnIPPpt4vVyUfEbS6pJLqtB ReIg2h+n5SPEk1m4sBUwzQJ3iNK23Zlaj8gnOqgm+Il3H3+wLEoe4wlv9dAq1g/mc5x8CFwnu5amy yok/juvhvHhPvEKeqj0RG8yt7gv+4Yw/hbSjoxrhH4NlesDyrH6qr3CNcQcjWlYtc2EO3+rxjcAZO SgHlHMWakRUyT4qe4H3VBC7rM3Sy37k9PHEPh9s7ZLTKL22TyJ+xNYv/RgxonCNoB2pErYRCUmX/x TSTIaU5Q==; 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 1kRxiV-0004Bg-Nq; Mon, 12 Oct 2020 13:18:19 +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 12F7B300DB4; Mon, 12 Oct 2020 15:18:18 +0200 (CEST) Received: by hirez.programming.kicks-ass.net (Postfix, from userid 1000) id EB75F20116727; Mon, 12 Oct 2020 15:18:17 +0200 (CEST) Date: Mon, 12 Oct 2020 15:18:17 +0200 From: Peter Zijlstra To: Dietmar Eggemann Cc: tglx@linutronix.de, mingo@kernel.org, linux-kernel@vger.kernel.org, bigeasy@linutronix.de, qais.yousef@arm.com, swood@redhat.com, valentin.schneider@arm.com, juri.lelli@redhat.com, vincent.guittot@linaro.org, rostedt@goodmis.org, bsegall@google.com, mgorman@suse.de, bristot@redhat.com, vincent.donnefort@arm.com, tj@kernel.org Subject: Re: [PATCH -v2 07/17] sched: Fix hotplug vs CPU bandwidth control Message-ID: <20201012131817.GP2651@hirez.programming.kicks-ass.net> References: <20201005145717.346020688@infradead.org> <20201005150921.661842442@infradead.org> <336a3916-1dd8-98cf-44e8-88dbf27018d5@arm.com> <20201012125200.GW2628@hirez.programming.kicks-ass.net> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20201012125200.GW2628@hirez.programming.kicks-ass.net> Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Mon, Oct 12, 2020 at 02:52:00PM +0200, Peter Zijlstra wrote: > On Fri, Oct 09, 2020 at 10:41:11PM +0200, Dietmar Eggemann wrote: > > On 05/10/2020 16:57, Peter Zijlstra wrote: > > > Since we now migrate tasks away before DYING, we should also move > > > bandwidth unthrottle, otherwise we can gain tasks from unthrottle > > > after we expect all tasks to be gone already. > > > > > > Also; it looks like the RT balancers don't respect cpu_active() and > > > instead rely on rq->online in part, complete this. This too requires > > > we do set_rq_offline() earlier to match the cpu_active() semantics. > > > (The bigger patch is to convert RT to cpu_active() entirely) > > > > > > Since set_rq_online() is called from sched_cpu_activate(), place > > > set_rq_offline() in sched_cpu_deactivate(). > > > [ 76.215229] WARNING: CPU: 1 PID: 1913 at kernel/irq_work.c:95 irq_work_queue_on+0x108/0x110 > > > [ 76.341076] irq_work_queue_on+0x108/0x110 > > [ 76.349185] pull_rt_task+0x58/0x68 > > [ 76.352673] balance_rt+0x84/0x88 > > > balance_rt() checks via need_pull_rt_task() that rq is online but it > > looks like that with RT_PUSH_IPI pull_rt_task() -> tell_cpu_to_push() > > calls irq_work_queue_on() with cpu = rto_next_cpu(rq->rd) and this one > > can be offline here as well now. > > Hurmph... so if I read this right, we reach offline with overload set? > > Oooh, I think I see how that happens.. I think the below two hunks need to be reverted from the patch. Can you confirm? --- a/kernel/sched/deadline.c +++ b/kernel/sched/deadline.c @@ -2326,9 +2326,6 @@ static void rq_online_dl(struct rq *rq) /* Assumes rq->lock is held */ static void rq_offline_dl(struct rq *rq) { - if (rq->dl.overloaded) - dl_clear_overload(rq); - cpudl_clear(&rq->rd->cpudl, rq->cpu); cpudl_clear_freecpu(&rq->rd->cpudl, rq->cpu); } --- a/kernel/sched/rt.c +++ b/kernel/sched/rt.c @@ -2245,9 +2245,6 @@ static void rq_online_rt(struct rq *rq) /* Assumes rq->lock is held */ static void rq_offline_rt(struct rq *rq) { - if (rq->rt.overloaded) - rt_clear_overload(rq); - __disable_runtime(rq); cpupri_set(&rq->rd->cpupri, rq->cpu, CPUPRI_INVALID);