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=-2.2 required=3.0 tests=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 C9EC4C3A5A8 for ; Wed, 4 Sep 2019 17:39:03 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 9C59321883 for ; Wed, 4 Sep 2019 17:39:03 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1730099AbfIDRjC (ORCPT ); Wed, 4 Sep 2019 13:39:02 -0400 Received: from mail-pf1-f195.google.com ([209.85.210.195]:44051 "EHLO mail-pf1-f195.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1727809AbfIDRjC (ORCPT ); Wed, 4 Sep 2019 13:39:02 -0400 Received: by mail-pf1-f195.google.com with SMTP id q21so8654771pfn.11; Wed, 04 Sep 2019 10:39:01 -0700 (PDT) X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20161025; h=x-gm-message-state:subject:to:cc:references:from:message-id:date :user-agent:mime-version:in-reply-to:content-language :content-transfer-encoding; bh=KnvfsSXVbwlDdjXbwbCBJbJBscMecP2Y83R9nu77QrY=; b=W0m8p/8M5k1Vf4lOjxwRazjXPVDZWgSpR+qgH6StaPwOejJv5NzV9jvwP/3CuhNwkI T/mTtNCnRg4fLeqso22vLhRUZi07GTOFRn7tCJOK1QGkBlS0pLh1RJPHAn7DVhcxv6e7 WDBMbP8D0iY60BAVP2FUXUcP9HvHo63216NccbvAPyLHnvrPmZGtT5aSLhtHiQSFNhah 8FDzxM+5icfIw5kkSUOVOyiLp/oNl/f2LKSSB8XtLHbsZy6hrHgw2H7pl4aTUMnMZq5D YZRqY2q2L9vOzwo+TTkC9MVmCmtvndP6l+mMBI4jFL8yoEPziYC3ande2J+ktG44efRP Xe5w== X-Gm-Message-State: APjAAAVXZqRElTbH3tvrxvtwqByjaICjLD7kQlgaEsH0HpK13TNla6iC ay3gg9n/ekDxQVhyc7+7Ryk= X-Google-Smtp-Source: APXvYqzrk/gkg2yGQWmQ4/JeJVdU8iF4leHlHSGlyvREresBS+YkyH/0INQtThrw0f/ygpLmb9mz8g== X-Received: by 2002:a63:ff65:: with SMTP id s37mr35380567pgk.102.1567618741236; Wed, 04 Sep 2019 10:39:01 -0700 (PDT) Received: from desktop-bart.svl.corp.google.com ([2620:15c:2cd:202:4308:52a3:24b6:2c60]) by smtp.gmail.com with ESMTPSA id v15sm23521222pfn.69.2019.09.04.10.38.59 (version=TLS1_3 cipher=TLS_AES_128_GCM_SHA256 bits=128/128); Wed, 04 Sep 2019 10:39:00 -0700 (PDT) Subject: Re: [PATCH 1/4] softirq: implement IRQ flood detection mechanism To: Daniel Lezcano , Ming Lei Cc: Keith Busch , Hannes Reinecke , Sagi Grimberg , linux-scsi@vger.kernel.org, Peter Zijlstra , Long Li , John Garry , LKML , linux-nvme@lists.infradead.org, Jens Axboe , Ingo Molnar , Thomas Gleixner , Christoph Hellwig References: <20190827225827.GA5263@ming.t460p> <20190828110633.GC15524@ming.t460p> <20190828135054.GA23861@ming.t460p> <20190903033001.GB23861@ming.t460p> <299fb6b5-d414-2e71-1dd2-9d6e34ee1c79@linaro.org> <20190903063125.GA21022@ming.t460p> <6b88719c-782a-4a63-db9f-bf62734a7874@linaro.org> <20190903072848.GA22170@ming.t460p> <6f3b6557-1767-8c80-f786-1ea667179b39@acm.org> <2a8bd278-5384-d82f-c09b-4fce236d2d95@linaro.org> From: Bart Van Assche Message-ID: Date: Wed, 4 Sep 2019 10:38:59 -0700 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:60.0) Gecko/20100101 Thunderbird/60.8.0 MIME-Version: 1.0 In-Reply-To: <2a8bd278-5384-d82f-c09b-4fce236d2d95@linaro.org> Content-Type: text/plain; charset=utf-8; format=flowed Content-Language: en-US Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On 9/4/19 10:31 AM, Daniel Lezcano wrote: > On 04/09/2019 19:07, Bart Van Assche wrote: >> Only if CONFIG_IRQ_TIME_ACCOUNTING has been enabled. However, I don't >> know any Linux distro that enables that option. That's probably because >> that option introduces two rdtsc() calls in each interrupt. Given the >> overhead introduced by this option, I don't think this is the solution >> Ming is looking for. > > Was this overhead reported somewhere ? I think it is widely known that rdtsc is a relatively slow x86 instruction. So I expect that using that instruction will cause a measurable overhead if it is called frequently enough. I'm not aware of any publicly available measurement data however. Bart.