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=-4.1 required=3.0 tests=BAYES_00,DKIMWL_WL_HIGH, DKIM_SIGNED,DKIM_VALID,DKIM_VALID_AU,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 63F68C4727C for ; Thu, 1 Oct 2020 13:56:46 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 11BBA221F0 for ; Thu, 1 Oct 2020 13:56:44 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1601560604; bh=o6qC8bC+K4scG1XPUArlJlnEglhhA7NyUzceP6nkYdI=; h=Date:From:To:Cc:Subject:References:In-Reply-To:List-ID:From; b=slCPLcw+XfMoUM9NiUEj+xsxBoI8L5H/lZvxd0508/hAU/imH6rAfDWMe5XlIlkKl +0MGB0ziXy5SOE5pn5c2zt62tQNqecFDu9V42umypolVtIJgLCH3jeDQNmwJb7WExV PMks0iK81+U5ZL2WJOYTCljvcsqtstw43AVGANKo= Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1732139AbgJAN4n (ORCPT ); Thu, 1 Oct 2020 09:56:43 -0400 Received: from mail.kernel.org ([198.145.29.99]:48826 "EHLO mail.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1732018AbgJAN4n (ORCPT ); Thu, 1 Oct 2020 09:56:43 -0400 Received: from localhost (fla63-h02-176-172-189-251.dsl.sta.abo.bbox.fr [176.172.189.251]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by mail.kernel.org (Postfix) with ESMTPSA id 2B5A720872; Thu, 1 Oct 2020 13:56:42 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1601560602; bh=o6qC8bC+K4scG1XPUArlJlnEglhhA7NyUzceP6nkYdI=; h=Date:From:To:Cc:Subject:References:In-Reply-To:From; b=MXeH6FmIoCrfau0W+WEVxQ2VRPiAykZjm2GMGlUsh12yFePp1P8OfDU9y4YF/flEM MSbl46cqF3QyJirMrdBjRZAVUJJcW7N6F4JPKxVSba6zbSRfU/L6n5//FXQ6rFK+vI RnXQMZb6DOSyo1ig6sI67GlpHT7Y41BHNna95WqI= Date: Thu, 1 Oct 2020 15:56:40 +0200 From: Frederic Weisbecker To: Alex Belits Cc: "rostedt@goodmis.org" , Prasun Kapoor , "mingo@kernel.org" , "davem@davemloft.net" , "linux-api@vger.kernel.org" , "peterz@infradead.org" , "linux-arch@vger.kernel.org" , "catalin.marinas@arm.com" , "tglx@linutronix.de" , "will@kernel.org" , "linux-arm-kernel@lists.infradead.org" , "linux-kernel@vger.kernel.org" , "netdev@vger.kernel.org" Subject: Re: [PATCH v4 03/13] task_isolation: userspace hard isolation from kernel Message-ID: <20201001135640.GA1748@lothringen> References: <04be044c1bcd76b7438b7563edc35383417f12c8.camel@marvell.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: Precedence: bulk List-ID: X-Mailing-List: linux-api@vger.kernel.org On Wed, Jul 22, 2020 at 02:49:49PM +0000, Alex Belits wrote: > +/* > + * Description of the last two tasks that ran isolated on a given CPU. > + * This is intended only for messages about isolation breaking. We > + * don't want any references to actual task while accessing this from > + * CPU that caused isolation breaking -- we know nothing about timing > + * and don't want to use locking or RCU. > + */ > +struct isol_task_desc { > + atomic_t curr_index; > + atomic_t curr_index_wr; > + bool warned[2]; > + pid_t pid[2]; > + pid_t tgid[2]; > + char comm[2][TASK_COMM_LEN]; > +}; > +static DEFINE_PER_CPU(struct isol_task_desc, isol_task_descs); So that's quite a huge patch that would have needed to be split up. Especially this tracing engine. Speaking of which, I agree with Thomas that it's unnecessary. It's too much code and complexity. We can use the existing trace events and perform the analysis from userspace to find the source of the disturbance. Thanks.