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=-13.7 required=3.0 tests=BAYES_00, HEADER_FROM_DIFFERENT_DOMAINS,INCLUDES_CR_TRAILER,INCLUDES_PATCH, MAILING_LIST_MULTI,SPF_HELO_NONE,SPF_PASS,URIBL_BLOCKED autolearn=unavailable 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 8914BC83012 for ; Wed, 2 Dec 2020 14:21:43 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 390D5221EB for ; Wed, 2 Dec 2020 14:21:43 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1730375AbgLBOV0 (ORCPT ); Wed, 2 Dec 2020 09:21:26 -0500 Received: from foss.arm.com ([217.140.110.172]:41436 "EHLO foss.arm.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1726729AbgLBOV0 (ORCPT ); Wed, 2 Dec 2020 09:21:26 -0500 Received: from usa-sjc-imap-foss1.foss.arm.com (unknown [10.121.207.14]) by usa-sjc-mx-foss1.foss.arm.com (Postfix) with ESMTP id B42AC30E; Wed, 2 Dec 2020 06:20:40 -0800 (PST) Received: from C02TD0UTHF1T.local (unknown [10.57.23.201]) by usa-sjc-imap-foss1.foss.arm.com (Postfix) with ESMTPSA id 1E8933F718; Wed, 2 Dec 2020 06:20:35 -0800 (PST) Date: Wed, 2 Dec 2020 14:20:33 +0000 From: Mark Rutland To: Alex Belits Cc: "nitesh@redhat.com" , "frederic@kernel.org" , Prasun Kapoor , "linux-api@vger.kernel.org" , "davem@davemloft.net" , "trix@redhat.com" , "mingo@kernel.org" , "catalin.marinas@arm.com" , "rostedt@goodmis.org" , "linux-kernel@vger.kernel.org" , "peterx@redhat.com" , "tglx@linutronix.de" , "linux-arch@vger.kernel.org" , "mtosatti@redhat.com" , "will@kernel.org" , "peterz@infradead.org" , "leon@sidebranch.com" , "linux-arm-kernel@lists.infradead.org" , "pauld@redhat.com" , "netdev@vger.kernel.org" Subject: Re: [PATCH v5 7/9] task_isolation: don't interrupt CPUs with tick_nohz_full_kick_cpu() Message-ID: <20201202142033.GD66958@C02TD0UTHF1T.local> References: <8d887e59ca713726f4fcb25a316e1e932b02823e.camel@marvell.com> <76ed0b222d2f16fb5aebd144ac0222a7f3b87fa1.camel@marvell.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <76ed0b222d2f16fb5aebd144ac0222a7f3b87fa1.camel@marvell.com> Precedence: bulk List-ID: X-Mailing-List: linux-api@vger.kernel.org On Mon, Nov 23, 2020 at 05:58:22PM +0000, Alex Belits wrote: > From: Yuri Norov > > For nohz_full CPUs the desirable behavior is to receive interrupts > generated by tick_nohz_full_kick_cpu(). But for hard isolation it's > obviously not desirable because it breaks isolation. > > This patch adds check for it. > > Signed-off-by: Yuri Norov > [abelits@marvell.com: updated, only exclude CPUs running isolated tasks] > Signed-off-by: Alex Belits > --- > kernel/time/tick-sched.c | 4 +++- > 1 file changed, 3 insertions(+), 1 deletion(-) > > diff --git a/kernel/time/tick-sched.c b/kernel/time/tick-sched.c > index a213952541db..6c8679e200f0 100644 > --- a/kernel/time/tick-sched.c > +++ b/kernel/time/tick-sched.c > @@ -20,6 +20,7 @@ > #include > #include > #include > +#include > #include > #include > #include > @@ -268,7 +269,8 @@ static void tick_nohz_full_kick(void) > */ > void tick_nohz_full_kick_cpu(int cpu) > { > - if (!tick_nohz_full_cpu(cpu)) > + smp_rmb(); What does this barrier pair with? The commit message doesn't mention it, and it's not clear in-context. Thanks, Mark. > + if (!tick_nohz_full_cpu(cpu) || task_isolation_on_cpu(cpu)) > return; > > irq_work_queue_on(&per_cpu(nohz_full_kick_work, cpu), cpu); > -- > 2.20.1 >