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=-3.6 required=3.0 tests=BAYES_00,DKIM_SIGNED, DKIM_VALID,DKIM_VALID_AU,FREEMAIL_FORGED_FROMDOMAIN,FREEMAIL_FROM, HEADER_FROM_DIFFERENT_DOMAINS,MAILING_LIST_MULTI,SPF_HELO_NONE,SPF_PASS, URIBL_BLOCKED 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 57965C433DF for ; Thu, 15 Oct 2020 01:27:58 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id E7B0422254 for ; Thu, 15 Oct 2020 01:27:57 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (2048-bit key) header.d=gmail.com header.i=@gmail.com header.b="iQR8YlaJ" Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1732039AbgJOB15 (ORCPT ); Wed, 14 Oct 2020 21:27:57 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:48750 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1727165AbgJOB14 (ORCPT ); Wed, 14 Oct 2020 21:27:56 -0400 Received: from mail-io1-xd42.google.com (mail-io1-xd42.google.com [IPv6:2607:f8b0:4864:20::d42]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 913EFC0613B3 for ; Wed, 14 Oct 2020 18:27:56 -0700 (PDT) Received: by mail-io1-xd42.google.com with SMTP id 67so2254745iob.8 for ; Wed, 14 Oct 2020 18:27:56 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=gmail.com; s=20161025; h=mime-version:references:in-reply-to:from:date:message-id:subject:to :cc; bh=GLOACr1Upy7vf7oHVF5/pEcrKvzTlyyjv59H5BxHvSs=; b=iQR8YlaJOmts+WjbEsLoEE9pSWvn3NDkUi0opGfDG7lGOa19zGlr1v5MITsSiA142y Bg1h2TaJeaW14PzH05w8XhTZqujMlur7EOsX0qVQ69TcFzeHwJvR+3jxe3RiOPi2v8Tg TFYYc1LhJEC2GZude+V2g1eAJhAa0chE8flEk3/BBs8gDHvtcBeQydQRgoBq3zYdYoE8 nXO0E9BvTol1LRq8Y4/Gub4zGiuS8EdG+xyqqO63KxG5gXvXU82/VE2hPhPJjrgXu5cD dIgozcPO2+QbQrJx06anE9iZMvXC2WyL4T6vgTuB2p/Dihe9r7tuS4nkSKYPLZiolqPY DexQ== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20161025; h=x-gm-message-state:mime-version:references:in-reply-to:from:date :message-id:subject:to:cc; bh=GLOACr1Upy7vf7oHVF5/pEcrKvzTlyyjv59H5BxHvSs=; b=pqa+IycqQBKPKi3vCvi2PMsMiH+CIG05Xc7uCDh+/dYdwHKDJGF+Pdk1+/ij9wLLaf 90uKFm40jxqeO/aAYMz3I3C3A9gMJC9aH97TM6zxnccy0tml559KwwetqMnAZV4KGocp JZ6on3A++tVe7z21L+Apd9OB6fBgNDepfRV1VilVgLukwBYH4RTNHAeSKOKfxtPnPNb8 5UADRP9QUdn9/pBS0oGYqke2livoRSRDnwumZtvrgM5HcSKdOj/3Xz+/lC8tczlS6VXA 5uDEnFOClJn6N9MnJTVq/8abN3EIbSbWftB5+4ffWY/+BdSgS9mcRY85tRs54vGfoPn5 wVPg== X-Gm-Message-State: AOAM532izRl1gpQgzTS8Wmdc/Ydjpk1wmEsoAtDAGrDVmhylVWnxplPK //869m1q6lkA8FZpLv6aI2gIRQRhoNwDcRSATA== X-Google-Smtp-Source: ABdhPJyvPB6meL78JmDv9rMOfzr/KbOaz5tX8A1mXzcJwpE4ZMDyo8+1l3v4cHbL8LvZKNUj6/2EOkiZmOIAkYQNiPU= X-Received: by 2002:a05:6638:97:: with SMTP id v23mr1785476jao.7.1602725275951; Wed, 14 Oct 2020 18:27:55 -0700 (PDT) MIME-Version: 1.0 References: <1602510644-24536-1-git-send-email-kernelfans@gmail.com> <20201014130223.GF2628@hirez.programming.kicks-ass.net> In-Reply-To: <20201014130223.GF2628@hirez.programming.kicks-ass.net> From: Pingfan Liu Date: Thu, 15 Oct 2020 09:27:44 +0800 Message-ID: Subject: Re: [PATCH] sched/cputime: correct account of irqtime To: Peter Zijlstra Cc: LKML , Ingo Molnar , Juri Lelli , Vincent Guittot , Dietmar Eggemann , Steven Rostedt , Ben Segall , Mel Gorman , Thomas Gleixner , Andy Lutomirski , Will Deacon , "Paul E. McKenney" , Frederic Weisbecker , Allen Pais , Romain Perier Content-Type: text/plain; charset="UTF-8" Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Wed, Oct 14, 2020 at 9:02 PM Peter Zijlstra wrote: > > On Mon, Oct 12, 2020 at 09:50:44PM +0800, Pingfan Liu wrote: > > __do_softirq() may be interrupted by hardware interrupts. In this case, > > irqtime_account_irq() will account the time slice as CPUTIME_SOFTIRQ by > > mistake. > > > > By passing irqtime_account_irq() an extra param about either hardirq or > > softirq, irqtime_account_irq() can handle the above case. > > I'm not sure I see the scenario in which it goes wrong. > > irqtime_account_irq() is designed such that we're called with the old > preempt_count on enter and the new preempt_count on exit. This way we'll > accumuate the delta to the previous context. > Oops! You are right, the time delta between a softirq and a interrupting hardirq should be accounted into the softrq. Thanks for your clear explanation. Regards, Pingfan