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=-2.0 required=3.0 tests=DKIM_INVALID,DKIM_SIGNED, HEADER_FROM_DIFFERENT_DOMAINS,MAILING_LIST_MULTI,SPF_HELO_NONE,SPF_PASS, USER_AGENT_SANE_1 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 7FAC7C43603 for ; Wed, 18 Dec 2019 12:30:04 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 46A8F2176D for ; Wed, 18 Dec 2019 12:30:04 +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="0DgA0W9l" Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1726710AbfLRMaD (ORCPT ); Wed, 18 Dec 2019 07:30:03 -0500 Received: from merlin.infradead.org ([205.233.59.134]:36570 "EHLO merlin.infradead.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1726545AbfLRMaD (ORCPT ); Wed, 18 Dec 2019 07:30:03 -0500 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:Resent-Date: Resent-From:Resent-Sender:Resent-To:Resent-Cc:Resent-Message-ID:List-Id: List-Help:List-Unsubscribe:List-Subscribe:List-Post:List-Owner:List-Archive; bh=WsfnNd7m2nvvl03QBT9ECyml/bzyuRqjZFKsto4Vzsg=; b=0DgA0W9llHe5C9DFdwetb4wNv 1C43E4j/YR7Ex8bi/XiWUwLPzzczrdH3iBq5Pg6NyJAIpYePKI+chlpY6UFcW7Givfi6B5VptscDP N+0kXd9lM2tLT5HHPpor8skjygrw3ztPgFJh0N/8tSj7FbsvGdYHe1ZDiyl8+rQiG6rVzOykB71IX AObFVoToGixx7PdzxtzEWhJ/8s93CH3EOMVqdXnZ142uutwz7zFiEzunGR6JHxPqceRlDAVgwZnIf NwuH/Jsve3rOH/VLsrWW0kyqAvppzYNSJVZuT8Ghmpfl4B4X8rCbrXM14v4LELNPivzpt5pz9sCGA bnhx5ETOA==; 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 1ihYSF-0003IU-82; Wed, 18 Dec 2019 12:29:27 +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 46B16300F29; Wed, 18 Dec 2019 13:27:59 +0100 (CET) Received: by hirez.programming.kicks-ass.net (Postfix, from userid 1000) id 4CC6529DFB923; Wed, 18 Dec 2019 13:29:22 +0100 (CET) Date: Wed, 18 Dec 2019 13:29:22 +0100 From: Peter Zijlstra To: Ming Lei Cc: Thomas Gleixner , Jens Axboe , linux-kernel@vger.kernel.org, linux-block@vger.kernel.org, Long Li , Ingo Molnar , Christoph Hellwig , Keith Busch , Sagi Grimberg , John Garry , Hannes Reinecke Subject: Re: [RFC PATCH 2/3] softirq: implement interrupt flood detection Message-ID: <20191218122922.GR2871@hirez.programming.kicks-ass.net> References: <20191218071942.22336-1-ming.lei@redhat.com> <20191218071942.22336-3-ming.lei@redhat.com> <20191218104941.GR2844@hirez.programming.kicks-ass.net> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20191218104941.GR2844@hirez.programming.kicks-ass.net> User-Agent: Mutt/1.10.1 (2018-07-13) Sender: linux-block-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-block@vger.kernel.org On Wed, Dec 18, 2019 at 11:49:41AM +0100, Peter Zijlstra wrote: > > _If_ you want to do something like this, do it like the below. That only > adds a few instruction to irq_exit() and only touches a cacheline that's > already touched. > > It computes both the avg duration and the avg inter-arrival-time of > hardirqs. Things get critical when: > > inter-arrival-avg < 2*duration-avg > > or something like that. Better yet, try something like: bool cpu_irq_heavy(int cpu) { return cpu_util_irq(cpu_rq(cpu)) >= arch_scale_cpu_capacity(cpu); }